A spinel nickel-iron oxide with Raman double characteristic peaks, preparation method and use thereof

Abstract

The present invention provides a nickel-iron oxide with a Raman double characteristic peak, wherein the nickel-iron oxide has a special Raman characteristic peak ratio of R=I T2g (3) / I A1g ≥0.55, showing the characteristics of low crystallinity and disordered coordination of local metal atoms, which results in the catalyst not having a good crystal structure and ordered coordination structure in the traditional sense. It unexpectedly realizes that the nickel-iron oxide catalyst can maintain high catalytic activity and long service life at the same time, which can effectively avoid the carbon deposition of alcohol molecules in the nickel-based material in the hydrogen production system and lead to performance degradation, so that this type of nickel-iron oxide oxidation alcohol hydrogen production technology route can be applied to industrial production, which is extremely innovative.

Description

Technical Field

[0001] The present invention relates to the field of electrocatalysis, and in particular to a spinel nickel-iron oxide with a Raman double characteristic peak, and a preparation method and application thereof. Background Art

[0002] Nickel (Ni), a non-precious metal, exhibits catalytic activity comparable to that of precious metals, exhibits excellent selectivity for catalytic reactions, and, due to its abundant reserves and low cost, is expected to become an industrialized catalyst in many catalytic fields. To enhance the catalytic activity of nickel-based materials, researchers have prepared highly electrocatalytically active nickel-based mixed metal oxide catalysts by doping them with other transition metals, such as iron, cobalt, and manganese. Among these, nickel-iron oxide is considered the most promising electrocatalytic material.

[0003] It is well known to those skilled in the art that the structure and morphology of a material fundamentally determine the performance of the material, and the performance can be the performance of various applications such as mechanics, magnetism, and catalysis exhibited by the material. In order to improve the performance of a material, the goal is to obtain the best possible structure and morphology. One of the most important uses of spinel-type (spinel-type oxides have the general formula AB2O4, where A is a divalent metal ion and B is a trivalent metal ion) nickel-iron oxide (NiFe2O4) in nickel-based materials is as a catalyst. The most important indicator for evaluating catalyst performance is catalytic activity. Therefore, in order to improve catalytic activity, the catalyst needs to have the best possible structure and morphology. For example, it is reported in the literature that in order to improve the inherent electrocatalytic performance of metal nanocrystals, the particle size, morphology, and chemical position of the nanocrystals are regulated taking into account the area effect, crystal plane effect, and the synergistic effect between different components. (To further promote the intrinsic electrocatalytic performance of noblemetal nanocrystals, a lot of researches have focused on the regulation ofparticle size, morphology and chemical composition due to the consideration of area effect, crystal plane effect and synergistic effect between different components. Chin. J. Catal 45, 2023, 6-16.). By regulating the optimal coordination and ordered atomic structure and phase structure, the catalyst exhibits higher activity (...and the optimized local chemical environment with more oxygen coordination and ordered atomic structure for the metalsite. Advanced Functional Materials, 2022, 32(38):2203520. Such highly openedhierarchical nanostructure for the synthesis of intermeordinated edge sites exhibited a susyantially enhanced activity tword the ORR.Nanoscale,11,2019,17301).

[0004] Spinel nickel-iron oxide is a crystalline catalyst when used as a catalyst. The ordered atomic structure provides the catalyst with a good crystal structure and an ordered coordination structure, which in turn enables the catalyst to exhibit excellent catalytic activity. Spinel nickel-iron oxide has a face-centered cubic structure, which consists of 64 tetrahedral sites and 32 octahedral sites. Half of the Fe 3+ The cations occupy the tetrahedral A sites, and the remaining Fe 3+ and Ni 2+ The cations are distributed in the octahedral B sites. Therefore, in the spinel nickel-iron oxide, Ni, Fe and O atoms have a strict coordination relationship. (Results Phys 16, 2022, 102916. Document 1), therefore, those skilled in the art are more committed to developing a spinel nickel-iron oxide with good crystal structure and orderly coordination. The good crystal structure and orderly coordination structure can be represented by the Raman peaks of the spinel nickel-iron oxide. The reason is that the spinel nickel-iron oxide has five obvious Raman characteristic peaks in the Raman spectrum, namely A 1g 、E g and 3 T 2g (like Figure 12 ). The symbols A, E and T represent the corresponding one-dimensional, two-dimensional and three-dimensional phonon modes respectively. 1g Corresponds to the symmetric stretching of the oxygen atoms of Fe-O (and Ni-O) tetrahedron. g Corresponds to the symmetrical bending of the oxygen atom relative to the metal ion. 2g (3) Corresponding to the asymmetric bending of the oxygen bond, T 2g (2) corresponds to the asymmetric stretching of Ni, Fe, and O atoms. At the same time, T 2g (2) and T 2g (3) is believed to be related to the vibration of the octahedron. In addition, T 2g (1) It can represent the parallel motion of tetrahedrons. Therefore, Raman spectroscopy can effectively show the crystal structure and coordination of spinel nickel-iron oxides (Results Phys 16, 2022, 102916. Reference 1).

[0005] It should be made clear that nickel-iron metal oxide has Eg, A in its Raman shift 1g 、T 2g The characteristic peak can only prove that it has a spinel structure, but cannot determine whether it has a good crystal structure and an ordered coordination structure. Whether the crystal structure is good and the coordination structure is ordered still needs to be calculated based on the Raman characteristic peak intensity (fitting peak area). According to the data in Reference 1 (such as Figure 12), the present application uses Origin software fitting (for details, see the test method of the double characteristic peak intensity ratio in the specific embodiment of the present application) to obtain the Raman shift of the spinel nickel-iron oxide in the Raman spectrum (Raman spectroscopy) = 500-720cm -1 There are two characteristic peaks in the time, A on the right 1g Peak and T on the left 2g (3) Peak, the intensity is used to calculate the intensity ratio of the double characteristic peaks, the intensity refers to the fitting Raman shift range (500-720cm -1 ) the peak area of ​​the characteristic peak, and the double characteristic peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g ≤0.45, due to T 2g (3) The peak corresponds to the asymmetric bending of the oxygen bond, A 1g For the symmetrical stretching of Fe-O (Ni-O) bonds, and the two characteristic peaks are adjacent, those skilled in the art believe that the double characteristic peaks are strong. A1g and I T2g(3) Ratio R=I T2g (3) / I A1g It can reflect the crystal structure and coordination of spinel nickel-iron oxide, and the double characteristic peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g ≤0.45 can be used as a basis for judging whether it is a spinel-type nickel-iron oxide with a good lattice structure and ordered coordination. (Reference 1 reports that NiFe2O4 has a spinel structure. Morphological examination shows that each grain of the material is composed of several tiny ferrite nanocrystals or nanoparticles. In pure nickel ferrite and doped nickel ferrite, Ni, Cd, Sr, Fe and O atoms are uniformly mixed, indicating that the spinel-structured NiFe2O4 in the article has a good crystal structure and an ordered coordination structure. Results Phys 16, 2022, 102916. J. Raman Spectrosc. 42, 2011, 1087-1094. Metall. Mater. Trans. A 50, 2019. 1571-1581.). Nickel-iron oxides with this characteristic peak ratio usually exhibit excellent catalytic activity because of their good crystal structure and ordered coordination structure.

[0006] Electrocatalysis is an interface-dominated reaction process, in which the activity of the catalyst is closely related to the adsorption / desorption behavior of reactants, intermediates, and products on the catalyst surface. For example, the alcohol oxidation reaction to hydrogen production differs from the electrolysis of water. Because alcohols are carbon-containing organic compounds, the oxidation reaction produces a variety of carbon-containing intermediates, which bind to the catalyst's active sites, leading to carbon deposition and catalyst poisoning, resulting in performance degradation. Carbon deposition occurs when the oxidation intermediate CO is adsorbed on the catalyst's active sites and undergoes a disproportionation reaction (2CO = C + CO2). This carbon deposition occupies the metal active sites with carbon, reducing the number of metal active sites and ultimately degrading catalytic performance. For example, methanol oxidation produces a variety of carbon-containing intermediates, such as CHO*, CHO*, and CO*. CO* is strongly adsorbed on the catalyst's active sites—specifically, its strong bond to the metal sites makes it difficult to dissociate and desorb. Consequently, a large number of active sites are occupied by CO* intermediates, which reduces the number of active sites and leads to catalyst poisoning. The strong binding of CO intermediates to metal sites on the surface of both noble metal and non-noble metal catalysts can lead to catalyst poisoning. (It is widely known that adsorbed CO is for med as a reaction intermediate at the lower potential region through methanol oxidation, which is strongly adsorbed on platinum and has a serious poisoning effect. K.Mastsu oka et al.Electro-oxidation ofmethanol and ethylene glycol on platinum in alkaline solution:Poisoning effects and product analysis.Electrochemica Acta 51,2005,1085-1090……On Rh(110),Ir(100),and Ni(100),removal of OH*and CO*,due to their too-strongbinding,……P.Ferrin et al.Structure sensitivity of methanol electrooxidation on transition metals J.Am.Soc.Chem.131,2009,14381-14389.)

[0007] Catalyst deactivation due to carbon deposition is a major issue in all reforming technologies. SA Theofa nidis et al. Mechanism of carbon deposits removal from supported Ni catalysts. Appl. Catal., B 239, 2018, 502-512. Carbon deposition is fatal to nickel-based catalysts and can seriously lead to catalyst deactivation. Carbon deposition in nickel-based cells is however fatal and must be considered during CO2 electrolysis. J. Power Sources 373, 2018, 54-60. Although the Raman characteristic peak ratio is R=I T2g (3) / I A1gNickel-iron oxide nanomaterials with a carbon ratio of ≤0.45 have a good crystal structure and an ordered coordination structure, and generally exhibit good catalytic performance. At the same time, they can inhibit the formation of carbon deposition to a certain extent during the reaction. However, as the reaction proceeds, the good crystal structure of nickel-iron oxide will be destroyed, resulting in degradation of the activity of nickel-iron oxide (The underlying concern is that the sample can inhibit the carbon deposition during the CH4 reduction, which may be beattributed to the unique spinel structure of NiFe2O4 oxygen carrier……But,thespecial structure gradually shrinks with increase of cycles due to the diverce of part of Fe element.Resu lting in the degeneration oxygen carrier reactivity.Z.Huang et al.Investigation on rea ctivity of iron nickel oxidesin chemical looping dry reforming.Energy 116,2016,53-63.). Therefore, spinel nickel-iron oxide with Raman characteristic peaks still cannot avoid the problem of carbon deposition, which leads to performance degradation or even deactivation, resulting in a short catalyst service life.

[0008] In order to ensure that nickel-iron oxide catalysts maintain high performance and long service life in alcohol oxidation reactions, it is necessary to avoid the problem of carbon deposition during the reaction that causes catalyst performance degradation. From the above carbon deposition principle, it can be seen that to avoid carbon deposition, it is first necessary to reduce the adsorption of the reaction intermediate CO by the metal active site. However, as mentioned above, good crystal structure and ordered coordination structure are the guarantee of high catalytic activity of nickel-iron oxide, and good adsorption capacity for reaction intermediates is also a manifestation of high activity. Therefore, the spinel type in the prior art has a Raman characteristic peak ratio of R=I T2g (3) / I A1g Nickel-iron oxide with a carbon content of ≤0.45 has a good crystal structure and an ordered coordination structure, and it is difficult to avoid carbon deposition during the oxidation reaction, which means that performance degradation and a short service life will inevitably occur. This is a fatal flaw for the industrial application of the catalyst.

[0009] Industrial-scale production requires that catalysts meet both high catalytic activity and long service life. However, the prior art requires that nickel-iron oxides have high catalytic activity by controlling their crystal structure and coordination structure, while the inevitable carbon deposition problem that occurs with this structure affects their service life. These are two conflicting requirements. For a long time, academic and industrial circles at home and abroad have been committed to how to avoid the carbon deposition problem of nickel-based catalysts, but existing research has failed to achieve a solution that simultaneously addresses the two requirements of high catalytic activity and long service life for nickel-iron oxide catalysts. Therefore, this also results in the fact that the nickel-iron oxide oxidation alcohol hydrogen production technology route cannot be truly applied to industrial production. Summary of the Invention

[0010] In response to the problems existing in the prior art, the present invention provides a special nickel-iron oxide with a double Raman characteristic peak, which has the characteristics of low crystal crystallinity and disordered local metal atom coordination. Unexpectedly, it achieves the characteristics of spinel-type nickel-iron oxide catalysts that can simultaneously maintain high catalytic activity and long service life, overcomes the technical prejudice that nickel-iron oxide is difficult to avoid carbon deposition in oxidation reactions, and overcomes the technical prejudice in the prior art that highly active nickel-iron oxide catalysts need to have a good crystal structure and an ordered coordination structure, so that this type of nickel-iron oxide oxidation alcohol hydrogen production technology route can be applied to industrial production, which is extremely innovative.

[0011] The first object of the present invention is to provide a spinel nickel-iron oxide having a Raman double characteristic peak, wherein the nickel-iron oxide has a general formula of Ni x Fe y O4, wherein 0.5≤x≤2, 1.5≤y≤4; in the Raman spectrum of the nickel-iron oxide, the Raman shift is 500-720cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), the double characteristic peaks include peak intensity I T2g(3) The left peak and the peak intensity I A1g Right peak, where the intensity ratio of the two characteristic peaks R=I T2g (3) / I A1g ≥0.55, the nickel-iron oxide contains Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ .

[0012] The nickel-iron oxide of the present invention has the above-mentioned general formula and double characteristic peaks in a specific ratio, and belongs to the spinel type nickel-iron oxide. The nickel-iron oxide has a special Raman characteristic peak ratio of R=I T2g (3) / I A1g≥0.55, showing low crystallinity and disordered coordination of local metal atoms, resulting in the catalyst not having a good crystal structure and ordered coordination structure in the traditional sense. Because the nickel-iron oxide lattice formed on the surface is imperfect, the metal-oxygen bond (MO) is distorted, which is manifested as a change in the Raman characteristic peak, specifically in the Raman shift = 500-720cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3) The peak intensity ratio has a special range. The present invention defines the ratio of the intensity of the double characteristic peaks as R = I T2g (3) / I A1g , R represents the imperfection of the nickel-iron oxide lattice structure, R≤0.45 represents a perfect lattice structure, R≥0.55 represents an imperfect lattice structure, perfect represents a good crystal structure and an ordered coordination structure, and imperfect represents a low crystallinity and a disordered coordination structure. The inventor unexpectedly discovered that it is this unique imperfect lattice structure that causes the nickel-iron oxide active site to be highly exposed, the Ni-O bond and the Fe-O bond length change, and at the same time, due to the presence of divalent and trivalent valence states in the nickel-iron bimetallic, the rich electronic structure and unique lattice structure of the metal site can be achieved in the process of oxidizing alcohols. Carbon-containing intermediates are quickly adsorbed and desorbed on the surface of the material, thereby showing the performance of oxidizing alcohols without carbon deposition. The nickel-iron oxide of the present invention has excellent anti-carbon deposition ability and exhibits excellent alcohol catalytic activity. Because the nickel-iron oxide has a unique bimetallic structure, it can effectively avoid the alcohol molecules in the hydrogen production system from being easily carbonized on the nickel-based material, resulting in performance degradation.

[0013] In different embodiments of the present invention, x and y have preferred ranges, and different values ​​of x and y can produce different electrical properties.

[0014] Preferably, 0.7≤x≤1.8, 1.7≤y≤3.5;

[0015] Preferably, 0.8≤x≤1.5, 1.8≤y≤3.0;

[0016] Preferably, 0.8≤x≤1.3, 1.8≤y≤2.5;

[0017] Preferably, 0.9≤x≤1.2, 1.9≤y≤2.2;

[0018] Preferably, x=0.95, y=2.05.

[0019] Furthermore, the nickel iron oxide has a Raman shift of 500-720 cm -1 Double characteristic peak A displayed in the interval 1g and T 2g (3) Peak intensity I A1g and I T2g(3)The ratio value (R=I T2g (3) / I A1g ) has a preferred range, and implementation schemes with different R values ​​correspond to different electrochemical properties.

[0020] Preferably, R=I T2g (3) / I A1g ≥0.65;

[0021] Preferably, R=I T2g (3) / I A1g ≥0.75;

[0022] Preferably, R=I T2g (3) / I A1g ≥0.85;

[0023] Preferably, R=I T2g (3) / I A1g ≥0.95;

[0024] Furthermore, the nickel-iron oxide is prepared by an in-situ growth method.

[0025] Each of the individual nickel-iron oxide embodiments described above may be combined with one or more of the nickel-iron oxide embodiments described previously therein.

[0026] A second object of the present invention is to provide a method for preparing the in-situ growth of nickel-iron oxide as described above, comprising the following steps:

[0027] 1) Provide Fe-containing 3+ , CH4N2O and NH4F mixed aqueous solution, first placing nickel foam (Ni foam) under a magnetic field for magnetization, wherein the nickel foam is added to the mixed aqueous solution and fully stirred, and the mixed aqueous solution and the nickel foam are hydrothermally treated together to obtain a nickel-iron oxide precursor; wherein the magnetic field strength of the magnetic field is 0.4-0.9T, the magnetization time is 5-15s, the hydrothermal treatment temperature is 85-150°C, with a tolerance of ±1.5°C, and the hydrothermal treatment time is 3-9h, with a tolerance of ±0.1h;

[0028] 2) heat-treating the nickel-iron oxide precursor in step 1) to obtain the nickel-iron oxide having a Raman double characteristic peak; wherein the heat treatment temperature is 200-500° C., with a deviation of ±1.5° C. allowed, and the heat treatment time is 1-3 h, with a deviation of ±0.1 h allowed.

[0029] The in-situ growth preparation method of nickel-iron oxide provided by the present invention uses nickel foam as the nickel source in the preparation process, and does not add other nickel-containing substances. In the original nickel foam, the metal state of nickel is elemental nickel (Ni). 3+ In aqueous solution, Fe 3+ The following substitution reaction will occur with the Ni element to form a nickel-iron oxide precursor. Among them, CH4N2O acts as a precipitant, making Fe 3+ Evenly dispersed in the mixed aqueous solution, it helps Fe 3+ NH4F fully reacts with Ni. NH4F acts as an etchant, etching the surface of nickel foam and facilitating the in-situ growth of nickel-iron oxide.

[0030] 2Fe 3+ +Ni→2Fe 2+ +Ni 2+

[0031] Fe 3+ +3H2O→Fe(OH)3+3H +

[0032] 2H + +Ni(OH)2→Ni 2+ +2H2O

[0033] Due to the occurrence of Fe 3+ The replacement reaction with Ni realizes that nickel foam provides nickel source in the whole preparation process. The advantage of this is that nickel-iron oxide nanoparticles can be grown in situ on the surface of nickel foam. Therefore, in the preparation process, iron salts containing trivalent iron are irreplaceable. If divalent iron salts are used, the replacement reaction cannot be achieved. In addition, if a nickel source is added during the preparation process, it will cause Fe 3+ It cannot undergo a replacement reaction with the Ni element in nickel foam, but takes precedence over Ni 2+ In other words, because the Ni in the nickel-iron oxide of the present invention comes from the replacement reaction, the nickel available for forming the nickel-iron oxide is insufficient compared to the preparation method using an external nickel source, resulting in an imperfect nickel-iron oxide lattice structure.

[0034] In addition, the present invention sets specific magnetic field conditions, through specific magnetization conditions and nickel foam substrate and the synergistic effect of all conditions such as precise control of raw material ratio, hydrothermal treatment temperature and time, heat treatment temperature and time, a spinel type nickel iron oxide of the imperfect structure of the present invention is grown in situ on the surface of nickel foam, unexpectedly realizing that spinel type nickel iron oxide catalyst can simultaneously maintain high catalytic activity and long service life, overcomes the technical prejudice that nickel iron oxide is difficult to avoid carbon deposition in oxidation reaction, overcomes the technical prejudice that highly active nickel iron oxide catalyst in the prior art needs to have good crystal structure, ordered coordination structure. The magnetic field magnetization process in the step 1) can effectively improve the electronic structure of nickel foam, and then promote the chemical reaction in the synthesis process to occur, which is derived from the magnetic field magnetization process can improve the magnetic domain order of the metal element nickel in the nickel foam material and eliminate magnetic domain walls. Because nickel foam becomes elemental metal nickel, it is a ferromagnetic material, and its interior contains numerous magnetic domain regions. So-called magnetic domain refers to small areas inside the magnetic material, each area containing a large number of atoms, and the magnetic moments of these atoms are all arranged in order. However, the directions of the atomic magnetic moments in different regions, that is, different magnetic domains, are not the same. The interface between each magnetic domain wall is called a magnetic domain wall. Therefore, before magnetization, the magnetic domain direction of the metallic nickel in the nickel foam is disordered to a certain extent, and the magnetic domain wall is clearly present. After magnetization, the direction of the magnetic moment of the magnetic domain in the nickel element will be consistent with the direction of the external macroscopic magnetic field, and the magnetic domain wall will disappear to a certain extent. These changes are beneficial to the interaction between metallic nickel and Fe in the solution. 3+ During the replacement reaction, electron transfer occurs, which promotes the generation of the synthesis reaction. Therefore, the two factors of magnetization time and magnetic field intensity are very critical for the synthesis process. Based on this, the nickel-iron precursor in the present invention has the characteristics of high structural disorder, which lays the foundation for the subsequent synthesis of nickel-iron oxide. The nickel-iron oxide of the present invention has the general formula Ni x Fe y O4, x, y exist in the range, which indicates that the lattice structure of the nickel-iron oxide of the present invention is not perfect and there is a large degree of disorder. The present invention can improve the conductivity and the number of active sites of the material by virtue of the excellent conductivity and huge surface area of ​​nickel foam, and promote the synthesis reaction by means of magnetic field magnetization of nickel foam. At the same time, due to the replacement reaction, the Ni and Fe elements in the whole iron-nickel oxide have Fe 3+ 、Fe 2+ 、Ni 3+ 、Ni 2+ The coexistence of multiple electronic valence states indicates that the electronic structure of the nickel-iron oxide of the present invention is complex and the electronic interactions between the elements are strong. The present invention finds that it is precisely because of this replacement reaction on the surface of nickel foam (Ni foam) that the Ni involved in the preparation of nickel-iron oxide 2+The content of is not sufficient, resulting in an imperfect nickel-iron oxide lattice formed on the surface and a distortion of the metal-oxygen bond (MO), which is manifested as a change in the Raman characteristic peak, specifically in the Raman shift = 500-720cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3) The peak intensity ratio has a special range. The present invention defines the ratio of the intensity of the double characteristic peaks as R = I T2g (3) / I A1g , R represents the degree of imperfection of the lattice structure of the nickel-iron oxide of the present invention. The present invention believes that it is this unique imperfect lattice structure that causes the active sites of the nickel-iron oxide to be highly exposed, and the bond lengths of the Ni-O and Fe-O bonds to change. At the same time, due to the presence of divalent and trivalent states of the nickel-iron bimetallic, the rich electronic structure of the metal site and the unique lattice structure can achieve rapid adsorption and desorption of carbon-containing intermediates on the surface of the material during the oxidation of alcohol, thereby exhibiting the performance of oxidizing alcohol without carbon deposition. The electrochemical properties of the nickel-iron oxide precursor are jointly exerted by the nickel foam and the nickel-iron metal oxide nanoparticles uniformly dispersed therein. Preferably, the Fe in the mixed aqueous solution provided in step 1) has a mass fraction wt% of 1:0.5~1.5:0.5~1.5 3+ The source is selected from any one or more of nitrate, sulfate, and chloride containing trivalent iron; the Fe 3+ The concentration is preferably 50 to 600 mg / mL; more preferably 150 to 500 mg / mL; more preferably 200 to 450 mg / mL; and more preferably 350 mg / mL.

[0035] Preferably, in step 1), the CH4N2O in the mixed aqueous solution with a mass fraction wt% of 1:0.5-1.5:0.5-1.5 is selected from any one or more of urea, thiourea, and sodium citrate containing CH4N2O, and the CH4N2O concentration is preferably 50-600 mg / mL; more preferably 150-500 mg / mL; more preferably 200-450 mg / mL; more preferably 250-400 mg / mL.

[0036] Preferably, the NH4F in the mixed aqueous solution with a mass fraction wt% of 1:0.5-1.5:0.5-1.5 in step 1) is used to provide NH4 + Cations and F - Anions are further used to assist the mixed aqueous solution in forming nanoparticles. + and F - The concentrations are 50 to 600 mg / mL, more preferably 150 to 500 mg / mL, more preferably 200 to 450 mg / mL, and more preferably 250 to 400 mg / mL.

[0037] Preferably, in step 1), the magnetic field strength of the magnetic field is 0.5-0.8 T, more preferably 0.6 T;

[0038] Preferably, in step 1), the magnetization time is 8-12 s, more preferably 9-11 s, more preferably 10 s;

[0039] Preferably, in step 1), the Fe 3+ , CH4N2O and NH4F mass fraction wt% is 1:0.8-1.2:0.8-1.2, more preferably 1:0.9-1.1:0.9-1.1, more preferably 1:0.95:1.05;

[0040] Preferably, the temperature of the hydrothermal treatment in step 1) is preferably 100-135° C., more preferably 125° C.; the time of the hydrothermal treatment is preferably 5-7 h, more preferably 5.5 h.

[0041] Preferably, the temperature of the heat treatment in step 2) is preferably 300-400°C, more preferably 340°C; the time of the heat treatment is preferably 2.5h; the atmosphere of the heat treatment is preferably any one or more of nitrogen, argon, and hydrogen-argon, more preferably any one or more of nitrogen and argon, more preferably argon.

[0042] The in-situ growth preparation method of nickel-iron oxide provided by the present invention can be used to prepare an electrode material consisting of a foam nickel substrate and nickel-iron metal oxide nanoparticles uniformly distributed on the surface of the foam nickel.

[0043] The third object of the present invention is to provide a catalyst, which comprises the nickel-iron oxide as described above or the nickel-iron oxide prepared by the method described above.

[0044] The fourth object of the present invention is to provide a use of the catalyst as described above in a chemical reaction; preferably, the chemical reaction is a hydrogen production reaction.

[0045] The fifth object of the present invention is to provide a hydrogen production system, wherein the hydrogen production system comprises the nickel-iron oxide as described above or the nickel-iron oxide prepared by the method as described above as a catalyst for the hydrogen production reaction, an external oxidation substrate and an electrolysis device; the schematic diagram of the hydrogen production system is as follows Figure 1 shown.

[0046] Preferably, the added oxidation substrate is selected from any one of an alcohol, a substance containing CON2H4, and a substance containing NH3·H2O; the alcohol is selected from any one or more of methanol, ethanol, and isopropanol; more preferably, selected from any one or more of methanol and isopropanol; more preferably, methanol; preferably, the CON2H4-containing substance is urea; preferably, the NH3·H2O-containing substance is aqueous ammonia. Preferably, the mass fraction of the added oxidation substrate in the hydrogen production reaction electrolyte is 5-30 wt%; more preferably, 10-25 wt%; more preferably, 15-20 wt%; and more preferably, 17 wt%.

[0047] A sixth object of the present invention is to provide a method for preparing hydrogen, the general reaction formula of which is as follows:

[0048]

[0049] In the formula, the nickel-iron oxide is the nickel-iron oxide as described above or the nickel-iron oxide prepared by the method described above;

[0050] Preferably, the pH value in the method is greater than 10; preferably, no CO or carbon deposits are generated in the method;

[0051] Preferably, the added oxidation substrate is selected from any one of an alcohol, a substance containing CON2H4, and a substance containing NH3·H2O; the alcohol is selected from any one or more of methanol, ethanol, and isopropanol; more preferably, selected from any one or more of methanol and isopropanol; more preferably, methanol; preferably, the CON2H4-containing substance is urea; preferably, the NH3·H2O-containing substance is aqueous ammonia. Preferably, the alcohol has a mass fraction of 5-30 wt% in the hydrogen production reaction electrolyte; more preferably, a mass fraction of 10-25 wt%; more preferably, a mass fraction of 15-20 wt%; and more preferably, a mass fraction of 17 wt%.

[0052] The beneficial effects of the present invention are:

[0053] (1) The present invention provides a spinel nickel-iron oxide with a Raman double characteristic peak, which has a double characteristic peak with a specific general formula and a specific ratio. On the one hand, it overcomes the technical prejudice of the prior art that high-performance catalysts need to have a good crystal structure and an ordered coordination structure. The nickel-iron oxide crystals of the present invention have low crystallinity and local metal atom coordination disorder, resulting in the catalyst not having a good structure and morphology in the traditional sense. However, it was unexpectedly found that although the nickel-iron oxide crystal structure and morphology of the present invention are imperfect, it has excellent anti-carbon deposition ability, overcoming the technical prejudice that nickel-iron oxide is difficult to avoid carbon deposition in oxidation reactions, and exhibiting excellent catalytic activity, so that this type of nickel-iron oxide oxidation alcohol hydrogen production technology route can be applied to industrial production, which is extremely innovative.

[0054] (2) The nickel-iron oxide of the present invention uses the nickel foam itself as a nickel source. The present invention sets specific magnetic field conditions. Through the synergistic effect of specific magnetization conditions and the nickel foam base, as well as the precise control of the raw material ratio, hydrothermal treatment temperature and time, heat treatment temperature and time, etc., a completely new structure of imperfect spinel-type nickel-iron oxide of the present invention is in situ grown on the surface of the nickel foam. After long-term use, the nickel-iron oxide will not fall off. Because of its unique bimetallic structure, the nickel-iron oxide can effectively avoid the carbon deposition of alcohol molecules in the nickel-based material in the hydrogen production system, which leads to performance degradation. The nickel-iron metal oxide nanoparticles of the present invention produce a synergistic effect with the nickel foam base, which can effectively improve the stability and service life of the catalyst material when oxidizing alcohol molecules, and has many advantages such as reducing the maintenance cost after the catalyst material is poisoned. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Schematic diagram of the hydrogen production system of the present invention.

[0056] Figure 2 This is the Raman spectrum of Example 1 of the nickel-iron oxide described in the present invention.

[0057] Figure 3 This is the X-ray diffraction pattern of Example 1 of the nickel-iron oxide described in the present invention.

[0058] Figure 4 This is the X-ray electron spectrum of Example 1 of the nickel-iron oxide described in the present invention.

[0059] Figure 5 This is an in-situ infrared spectrum of the methanol oxidation process of nickel-iron oxide Example 1 of the present invention.

[0060] Figure 6 This is a polarization curve diagram of the methanol oxidation reaction and oxygen evolution reaction of Example 1 of the nickel-iron oxide of the present invention.

[0061] Figure 7 This is an in-situ infrared spectrum of the methanol oxidation process of nickel-iron oxide Example 8 of the present invention.

[0062] Figure 8 This is the Raman spectrum of commercially available iron-nickel oxide A powder.

[0063] Figure 9 This is the in-situ infrared spectrum of the methanol oxidation process by commercially available iron-nickel oxide A.

[0064] Figure 10 This is a polarization curve diagram of methanol oxidation reaction and oxygen evolution reaction of comparative example 4 of nickel-iron oxide according to the present invention.

[0065] Figure 11 The thermogravimetric curves of Example 5 and Comparative Example 13 of the nickel-iron oxide of the present invention are shown.

[0066] Figure 12 This is the Raman spectrum in Reference 1.

[0067] Figure 13 This is the polarization curve diagram of the urea oxidation reaction and the ammonia oxidation reaction of Example 22 of the nickel-iron oxide described in the present invention. DETAILED DESCRIPTION

[0068] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the invention.In addition, should be understood that after reading the content of teaching of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the application's appended claims.

[0069] The characteristic parameter testing method of the present invention is as follows:

[0070] Raman spectroscopy test:

[0071] In the present invention, Raman analysis is used to characterize the electrode material. The instrument model is HORIBA Scientific Lab RAMH REvolution at 100-3000 cm -1 Raman measurements were performed within the Raman shift range.

[0072] In the present invention, the nickel-iron oxide contains Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ Metal ions can be proved by XPS test. Fitting the XPS test results, if there are peaks at the binding energy values ​​of (879.3±0.8eV), (873.7±0.8eV), (723.4±0.8eV), and (732.8±0.8eV), then it corresponds to Ni2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ ions, proving that Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ ion.

[0073] Dual characteristic peak intensity ratio:

[0074] In the present invention, when nickel iron oxide has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), the double characteristic peaks include peak intensity I T2g(3) The left peak has a peak intensity of I A1g The right peak, where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g ≥0.55, the final electrode material does not produce CO intermediates during the oxidation of methanol molecules. When the electrode material is prepared and stirred under different conditions, the intensity ratio of the double peaks will change. Therefore, in the present invention, the peak intensity ratio is calculated and used as a parameter to characterize the electrode material. For example, the peak intensity ratio of 500 to 720 cm -1 The Raman spectrum is used to perform peak fitting and peak intensity ratio calculation. Using the integration method, Origin software or other data analysis software is used for data integration, and the baseline is set to Y = 0 to obtain the mathematical areas of the two characteristic peaks. The intensity (fitted peak area) is used to calculate the intensity ratio of the two characteristic peaks. In this step of the calculation, the characteristic peak Raman shift is allowed to be ± 10cm -1 The key to the shift is to use the peak area as a comparison of intensity. The calculation formula is as follows:

[0075]

[0076] In-situ infrared detection technology test:

[0077] Attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) experiments were performed using a Nicolet 6700 FTIR spectrometer with an ECIR electrochemical cell (ATR instrument) on a PIKE VeeMAX III variable angle ATR accessory. The spectral resolution was set to 8 cm -1 The spectra are given in absorbance units defined as A = -log(R / R0), where R and R0 represent the reflected infrared intensities corresponding to the sample and reference single beam spectra, respectively.

[0078] A 60° Si crystal was used as a reflective crystal. A gold film was chemically deposited to enhance the signal. Electrocatalysts were dropped onto the Au film and used as the working electrode for the SEIRAS experiment, with a loading of 0.08 mg cm. -2 In all experiments, a platinum wire and an Ag / AgCl electrode were used as the counter electrode and reference electrode, respectively. An aqueous solution containing 1 M potassium hydroxide and 0.5 M methanol was used as the electrolyte. A chronopotentiostat was used at various potentials (0.35–0.65 V vs. Ag / AgCl). SEIRAS spectra were collected during the chronopotentiostat experiments.

[0079] Metal ion valence detection test:

[0080] In this invention, XPS test is applied to characterize nickel-iron oxide materials, and the instrument model used is ThermoScientific K-Alpha. After taking an appropriate amount of sample and pressing it into a pellet, it is attached to the sample plate and placed into the instrument. The pressure in the sample chamber is less than 2.0×10 -7 mbar, the sample was sent into the analysis chamber, the spot size was 400 μm, the operating voltage was 12 kV, the filament current was 6 mA, the narrow spectrum scanning energy was 50 eV, and the step size was 0.1 eV.

[0081] Hydrogen production performance test:

[0082] The hydrogen production performance test was carried out in a conventional three-electrode electrochemical cell using a CHI750E electrochemical workstation. Pt wire and Ag / AgCl reference electrode (3M KCl) were used as counter electrode and reference electrode, respectively. The working electrode was pretreated by 20 cyclic voltammetric scans from -1.5 to 1.0 V versus Ag / AgCl (3M KCl) at 10 mV s-1 in 1M KOH. For the oxygen evolution reaction (OER) performance, polarization curves were obtained by linear sweep voltammetry in 1M KOH at 5 mV s-1. -1 For the methanol oxidation reaction (MOR) performance, linear sweep voltammetry was performed at a scan rate of 5 mV s in a solution containing 1 M KOH and different mass fractions of the added oxidizing substrate. -1 The polarization curve was recorded at a scan rate of 1000 nm. Considering that industrial water electrolysis for hydrogen production needs to generate 300-600 mA cm at a voltage of 2 V, -2 The current density is 400 mA cm, so the inventors compared the current density required for the oxidation reaction of the added substrate and the OER reaction. -2The required voltage is used to compare hydrogen production performance. According to Faraday's law (Faraday's first law, Faraday's research shows that for a single electrolytic cell, during the electrolysis process, the amount of reduced material deposited on the cathode is proportional to the current intensity passing through it). The lower the voltage required for the anode reaction to produce the same current density, the lower the energy consumption of the cathode to produce the same amount of hydrogen, that is, the stronger the hydrogen production performance. Therefore, it is sufficient to compare the anode reaction potential.

[0083] Example 1

[0084] The method for preparing nickel-iron oxide of the present invention comprises the following steps:

[0085] 1) providing a mixed solution of Fe3(NO3)2, CH4N2O, and NH4F in a weight percent ratio of 1:0.95:1.05, first magnetizing nickel foam (Ni foam) in a magnetic field of 0.6 T for 10 seconds, adding a nickel foam substrate to the mixed solution and stirring thoroughly for 30 minutes, and then hydrothermally treating the mixed solution and the nickel foam at 125°C for 5.5 hours to prepare a nickel-iron oxide precursor;

[0086] 2) The electrode material precursor prepared in step 1) is subjected to heat treatment at 340° C. in an argon atmosphere for 2 hours to obtain the nickel-iron oxide.

[0087] Take the nickel iron oxide prepared in steps 1-2), such as Figure 2 It has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the double characteristic peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g =0.95, as shown in Table 2. Figure 3 The X-ray diffraction pattern of the nickel-iron oxide shows that it has a NiFe2O4 lattice structure, indicating that the general formula is Ni x Fe y In O4, x=1, y=2. Figure 4 As described above, it can be determined by fitting the XPS test data that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.8eV), Ni 3+ (873.3eV), Fe 2+ (723.1eV), Fe 3+ (733.2eV) metal characteristic peak, indicating that nickel iron oxide material has Ni2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ Metal ions coexist. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide as described in Example 1: Figure 5 As shown, the nickel-iron oxide of Example 1 does not show a characteristic peak related to CO (located at 1900-2200 cm -1 ).like Figure 6 As shown, the nickel iron oxide methanol oxidation reaction in Example 1 (17 wt% mass fraction) obtained 400 mA cm -2 The voltage required for the current density is 1.46 V, and the oxygen evolution reaction obtains 400 mA cm -2 The current density requires a voltage of 1.92 V. The methanol oxidation reaction saves 0.46 V, achieving energy-saving and efficient hydrogen production.

[0088] Example 2

[0089] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 2 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=0.5, y=1.5. Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.6eV), Ni 3+ (873.1eV), Fe 2+ (723.0eV), Fe 3+ (733.0eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ Metal ions coexist. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Example 2: The nickel-iron oxide in Example 2 did not show a characteristic peak related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1The nickel iron oxide methanol oxidation reaction (10 wt % mass fraction) in Example 2 should obtain 300 mA cm -2 The voltage required for the current density is 1.44 V, and the oxygen evolution reaction obtains 300 mA cm -2 The current density requires a voltage of 1.98 V. The methanol oxidation reaction saves 0.54 V, achieving energy-saving and efficient hydrogen production.

[0090] Example 3

[0091] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 3 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=2, y=4. Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.9eV), Ni 3+ (873.4eV), Fe 2+ (723.4eV), Fe 3+ (733.3eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ Metal ions coexist. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Example 3: The nickel-iron oxide in Example 3 did not show a characteristic peak related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 The nickel iron oxide methanol oxidation reaction in Example 3 (5 wt% mass fraction) obtained 100 mA cm -2 The voltage required for the current density is 1.41V, and the oxygen evolution reaction obtains 100mAcm -2 The current density requires a voltage of 1.78 V. The methanol oxidation reaction saves 0.36 V, achieving energy-saving and efficient hydrogen production.

[0092] Example 4

[0093] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 4 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=2, y=4. Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.9eV), Ni 3+ (873.4eV), Fe 2+ (723.4eV), Fe 3+ (733.3eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ Metal ions coexist. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Example 4: The nickel-iron oxide in Example 4 did not show a characteristic peak related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 The nickel iron oxide methanol oxidation reaction in Example 4 (30 wt % mass fraction) obtained 100 mA cm -2 The voltage required for the current density is 1.41V, and the oxygen evolution reaction obtains 100mAcm -2 The current density requires a voltage of 1.78 V. The methanol oxidation reaction saves 0.36 V, achieving energy-saving and efficient hydrogen production.

[0094] Example 5

[0095] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 5 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=1.2, y=2.2. Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2、Fe2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.8eV), Ni 3+ (873.5eV), Fe 2+ (723.3eV), Fe 3+ (733.5eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ Metal ions coexist. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Example 5: The nickel-iron oxide in Example 5 did not show a characteristic peak related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 The nickel iron oxide methanol oxidation reaction in Example 5 (25 wt % mass fraction) obtained 200 mA cm -2 The voltage required for the current density is 1.47 V, and the oxygen evolution reaction obtains 200 mA cm -2 The current density requires a voltage of 1.82 V. The methanol oxidation reaction saves 0.35 V, achieving energy-saving and efficient hydrogen production.

[0096] Example 6

[0097] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 6 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=1.4, y=3.2. Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.8eV), Ni 3+ (873.5eV), Fe 2+ (723.3eV), Fe 3+ (733.5eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe2+ 、Fe 3+ The metal ions coexist. Detection of the reaction intermediates during the electrooxidation of isopropanol by the nickel-iron oxide described in Example 6: The nickel-iron oxide described in Example 6 did not show a characteristic peak related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 The nickel iron oxide isopropanol oxidation reaction (10 wt % mass fraction) in Example 6 obtained 200 mA cm -2 The voltage required for the current density is 1.47 V, and the oxygen evolution reaction obtains 200 mA cm -2 The current density requires a voltage of 1.82 V. The isopropyl alcohol oxidation reaction saves 0.35 V, achieving energy-saving and efficient hydrogen production.

[0098] Example 7

[0099] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 7 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=1.7, y=2.1. Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.2eV), Ni 3+ (873.1eV), Fe 2+ (723.2eV), Fe 3+ (733.6eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ Metal ions coexist. Detection of reaction intermediates during the electrooxidation of ethanol by nickel-iron oxide in Example 7: The nickel-iron oxide in Example 7 did not show a characteristic peak related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 The nickel iron oxide ethanol oxidation reaction in Example 7 (15 wt % mass fraction) obtained 200 mA cm -2The voltage required for the current density is 1.52V, and the oxygen evolution reaction obtains 200mAcm -2 The current density requires a voltage of 1.82 V. The ethanol oxidation reaction saves 0.30 V, achieving energy-saving and efficient hydrogen production.

[0100] Example 8

[0101] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 8 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio R of the double characteristic peak intensities is shown in Table 2.

[0102] Detection of the reaction intermediates during the electrooxidation of methanol by nickel-iron oxide as described in Example 8: Figure 7 The nickel-iron oxide of Example 8 did not show a characteristic peak related to CO (located at 1900-2200 cm -1 ). The element content analysis showed that the general formula Ni x Fe y In O4, x=0.7, y=1.7. Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.5eV), Ni 3+ (873.1eV), Fe 2+ (723.9eV), Fe 3+ (733.4eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ The metal ions coexist. The nickel iron oxide methanol oxidation reaction in Example 8 obtained 400mA cm -2 The voltage required for the current density is 1.48 V, and the oxygen evolution reaction obtains 400 mA cm -2 The current density requires a voltage of 1.98 V. The methanol oxidation reaction saves 0.50 V, achieving energy-saving and efficient hydrogen production.

[0103] Example 9

[0104] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 9 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio R of the double characteristic peak intensities is shown in Table 2.

[0105] Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Example 9: No characteristic peaks related to CO (located at 1900-2200 cm) were observed in the in-situ infrared spectrum of the electrode material in Example 9 at a voltage of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ). The element content analysis showed that the general formula Ni x Fe y In O4, x=0.8, y=1.9. Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe 2p 1 / 2 、Ni2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.0eV), Ni 3+ (873.4eV), Fe 2+ (723.7eV), Fe 3+ (733.1eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ The metal ions coexist. The nickel iron oxide methanol oxidation reaction in Example 9 obtained 400mAcm -2 The voltage required for the current density is 1.49 V, and the oxygen evolution reaction obtains 400 mA cm -2 The current density requires a voltage of 1.98 V. The methanol oxidation reaction saves 0.49 V, achieving energy-saving and efficient hydrogen production.

[0106] Example 10

[0107] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 10 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe yIn O4, x=0.8 and y=2.4. Detection of the reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Example 10: The nickel-iron oxide in Example 10 showed no characteristic peaks related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum at a voltage of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ). Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.9eV), Ni 3+ (872.6eV), Fe 2+ (724.1eV), Fe 3+ (733.5eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ The metal ions coexist. The nickel iron oxide methanol oxidation reaction in Example 10 obtained 400mA cm -2 The voltage required for the current density is 1.47 V, and the oxygen evolution reaction obtains 400 mA cm -2 The current density requires a voltage of 1.98 V. The methanol oxidation reaction saves 0.51 V, achieving energy-saving and efficient hydrogen production.

[0108] Example 11

[0109] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 11 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=0.9, y=2.2. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Example 11: The nickel-iron oxide in Example 11 showed no characteristic peaks related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ). Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe2p 3 / 2The orbital can be fitted to Ni 2+ (879.9eV), Ni 3+ (872.6eV), Fe 2+ (724.1eV), Fe 3+ (733.5eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ The metal ions coexist. The nickel iron oxide methanol oxidation reaction in Example 11 obtained 400mA cm -2 The voltage required for the current density is 1.49 V, and the oxygen evolution reaction obtains 400 mA cm -2 The current density requires a voltage of 1.98 V. The methanol oxidation reaction saves 0.48 V, achieving energy-saving and efficient hydrogen production.

[0110] Example 12

[0111] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 12 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=1.5, y=2.5. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Example 12: The nickel-iron oxide in Example 12 showed no characteristic peaks related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ). Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.9eV), Ni 3+ (872.6eV), Fe 2+ (724.1eV), Fe 3+ (733.5eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ The metal ions coexist. The nickel iron oxide methanol oxidation reaction in Example 12 obtained 400mA cm-2 The voltage required for the current density is 1.59 V, and the oxygen evolution reaction obtains 400 mA cm -2 The current density requires a voltage of 1.98 V. The methanol oxidation reaction saves 0.41 V, achieving energy-saving and efficient hydrogen production.

[0112] Example 13

[0113] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 13 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=1.2, y=2.2. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Example 13: The nickel-iron oxide in Example 13 showed no characteristic peaks related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ). This indicates that the iron source can be replaced by a variety of water-soluble trivalent iron salts during the preparation process. Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.4eV), Ni 3 + (872.2eV), Fe 2+ (724.0eV), Fe 3+ (733.3eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3 + 、Fe 2+ 、Fe 3+ The metal ions coexist. The nickel iron oxide methanol oxidation reaction in Example 13 obtained 400mA cm -2 The voltage required for the current density is 1.56 V, and the oxygen evolution reaction obtains 400 mA cm -2 The current density requires a voltage of 1.98 V. The methanol oxidation reaction saves 0.42 V, achieving energy-saving and efficient hydrogen production.

[0114] Example 14

[0115] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 14 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=1.8, y=3.5. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide described in Example 14: The nickel-iron oxide described in Example 14 did not show a characteristic peak related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ). Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.4eV), Ni 3+ (872.2eV), Fe 2+ (724.0eV), Fe 3+ (733.3eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ The metal ions coexist. The nickel iron oxide methanol oxidation reaction in Example 14 obtained 400mA cm -2 The voltage required for the current density is 1.59 V, and the oxygen evolution reaction obtains 400 mA cm -2 The current density requires a voltage of 1.98 V. The methanol oxidation reaction saves 0.39 V, achieving energy-saving and efficient hydrogen production.

[0116] Example 15

[0117] This example is prepared by referring to the method of Example 1. The raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 15 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=1.3, y=2.5.

[0118] Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Example 15: The nickel-iron oxide in Example 15 showed no characteristic peaks for CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ). Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.4eV), Ni 3+ (872.2eV), Fe 2+ (724.0eV), Fe 3+ (733.3eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ The metal ions coexist. The nickel iron oxide methanol oxidation reaction in Example 15 obtained 400mAcm -2 The voltage required for the current density is 1.59 V, and the oxygen evolution reaction obtains 400 mA cm -2 The current density requires a voltage of 1.98 V. The methanol oxidation reaction saves 0.39 V, achieving energy-saving and efficient hydrogen production.

[0119] Example 16

[0120] This example is prepared by referring to the method of Example 1. The raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 16 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=0.7, y=2.1. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Example 16: The nickel-iron oxide in Example 16 showed no characteristic peaks related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ). Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+(879.4eV), Ni 3+ (872.2eV), Fe 2+ (724.0eV), Fe 3+ (733.3eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ The metal ions coexist. The nickel iron oxide methanol oxidation reaction in Example 16 obtained 400mA cm -2 The voltage required for the current density is 1.77V, and the oxygen evolution reaction obtains 400mAcm -2 The current density requires a voltage of 1.98 V. The methanol oxidation reaction saves 0.21 V, achieving energy-saving and efficient hydrogen production.

[0121] Example 17

[0122] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 17 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=1.9, y=3.2. Detection of the reaction intermediates during the electrooxidation of ethanol by nickel-iron oxide in Example 17: The nickel-iron oxide in Example 17 did not show a characteristic peak related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ). Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.4eV), Ni 3+ (872.2eV), Fe 2+ (724.0eV), Fe 3+ (733.3eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ The nickel iron oxide ethanol oxidation reaction in Example 17 obtained 200 mA cm -2The voltage required for the current density is 1.57V, and the oxygen evolution reaction obtains 200mAcm -2 The current density requires a voltage of 1.77 V. The methanol oxidation reaction saves 0.20 V, achieving energy-saving and efficient hydrogen production.

[0123] Example 18

[0124] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 18 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the ratio of the double characteristic peak intensity R is shown in Table 2. The element content analysis shows that the general formula Ni x Fe y In O4, x=1.1, y=1.8. Detection of the reaction intermediates during the electrooxidation of isopropanol by the nickel-iron oxide described in Example 18: The nickel-iron oxide described in Example 18 did not show a characteristic peak related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ). Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe2p 3 / 2 The orbital can be fitted to Ni 2+ (879.4eV), Ni 3+ (872.2eV), Fe 2+ (724.0eV), Fe 3+ (733.3eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ The metal ions coexist. The nickel iron oxide isopropanol oxidation reaction in Example 18 obtained 200 mA cm -2 The voltage required for the current density is 1.57V, and the oxygen evolution reaction obtains 200mAcm -2 The current density requires a voltage of 1.77 V. The methanol oxidation reaction saves 0.20 V, achieving energy-saving and efficient hydrogen production.

[0125] Example 19

[0126] This example refers to the preparation method of Example 1, and the raw materials and method parameters are shown in Table 1. The nickel iron oxide prepared in Example 19 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval1g and T 2g (3), wherein the ratio of the intensity of the double characteristic peaks R is shown in Table 2. Detection of the reaction intermediates during the electrooxidation of methanol by the nickel-iron oxide described in Example 19: The nickel-iron oxide described in Example 19 did not show a characteristic peak related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage period of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ). Using the XPS test data fitting results, it can be determined that Ni 2p 1 / 2 、Fe2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital can be fitted to Ni 2+ (879.1eV), Ni 3+ (872.1eV), Fe 2+ (724.2eV), Fe 3+ (733.1eV) metal characteristic peak, indicating that nickel iron oxide material has Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ The metal ions coexist. The nickel iron oxide methanol oxidation reaction in Example 19 obtained 400mA cm -2 The voltage required for the current density is 1.61 V, and the oxygen evolution reaction obtains 400 mA cm -2 The current density requires a voltage of 1.95 V. The methanol oxidation reaction saves 0.34 V, achieving energy-saving and efficient hydrogen production.

[0127] Table 1 Raw materials and method parameters for preparing nickel iron oxide in Examples 1-19

[0128]

[0129]

[0130] Table 1: Raw materials and method parameters for preparing nickel iron oxide in Examples 1-19

[0131]

[0132] Table 2 Double characteristic peak intensity ratio R of nickel iron oxide prepared in Example 1-19

[0133]

[0134] Table 2: Double characteristic peak intensity ratio R of nickel iron oxide prepared in Example 1-19

[0135]

[0136] Examples 20-27

[0137] Among the external oxidation substrates described in the present invention, urea (CON2H4) and ammonia (NH3·H2O), their molecular structures both contain NH bonds. Considering that the nickel-iron metal oxide has excellent oxidation activity for alcohol molecules, and alcohol molecules contain CH bonds, the inventors speculate that the nickel-iron metal oxide also has certain oxidation activity for urea and ammonia molecules. In other words, the nickel-iron metal oxide has certain oxidation activity for breaking CH bonds and NH bonds. Therefore, the nickel-iron oxides of Examples 20-27 of the present application all refer to the preparation methods, raw materials and method parameters of Examples 1-7, and only the external oxidation substrates are replaced with urea and ammonia with a mass fraction of 5-30% for electrochemical performance testing. The results are as follows. Figure 13 As mentioned above, under the same voltage, the current density of the nickel-iron oxide electrooxidation reaction of urea and ammonia in Example 22 far exceeds that of the traditional oxygen evolution reaction. -2 Compared with the current density, the potential required for the oxidation of urea and ammonia is 1.58V, which is much lower than the potential required for the traditional oxygen evolution reaction (2.24V), which achieves the effect of energy-saving hydrogen production. At a voltage of 1.5V vs. RHE, the oxidation currents of ammonia and urea are both higher than the oxygen evolution reaction current of the same material, indicating that the nickel-iron oxide of the present invention has high catalytic activity for ammonia and urea, and can achieve energy-saving effect of hydrogen production by electrolysis of water.

[0138] Comparative Example 1

[0139] Commercially available iron-nickel compound NiFe2O4 was purchased from Aladdin Reagent Company (hereinafter referred to as commercially available iron-nickel oxide compound A) and subjected to relevant Raman, in-situ infrared and electrochemical performance tests. Figure 8 As shown, commercially available iron-nickel oxide A has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g =0.47. The reaction intermediates in the electrooxidation of methanol by commercially available iron-nickel oxide A described in Comparative Example 1 were detected: Figure 9 As shown, the commercially available iron-nickel oxide A described in Comparative Example 1 has a characteristic peak related to CO (located at 1900-2200 cm -1 ), and at the same voltage, the methanol oxidation current is lower. Using the XPS test data fitting results, it can be judged that Ni 2p 1 / 2 、Fe 2p1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital cannot be fitted to Ni 3+ and Fe 2+ Characteristic peaks, indicating that the metal valence state of the commercially available iron-nickel oxide A only contains Ni 2+ and Fe 3+ The nickel iron oxide methanol oxidation reaction in Comparative Example 1 obtained 400 mA cm -2 The voltage required for the current density is 1.88V, and the oxygen evolution reaction obtains 400mAcm -2 The current density required a voltage of 1.85 V, and the methanol oxidation reaction activity was lower than the oxygen evolution reaction, failing to achieve energy conservation. This indicates that commercially available nickel-iron oxide NiFe2O4 does not possess the characteristics of the nickel-iron oxide described in the present invention, and therefore does not have the corresponding electrochemical properties.

[0140] Comparative Example 2

[0141] Commercially available iron-nickel compound NiFe2O4 was purchased from Macbeth Reagent Company (hereinafter referred to as commercially available iron-nickel oxide compound B) and subjected to relevant Raman, in-situ infrared and electrochemical performance tests. The purchased NiFe2O4 from company B has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g =0.38. Detection of reaction intermediates during the electrooxidation of methanol by commercially available iron-nickel oxide B in Comparative Example 2: The commercially available iron-nickel oxide B in Comparative Example 2 exhibited a characteristic peak related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ), and at the same voltage, the methanol oxidation current is lower. Using the XPS test data fitting results, it can be judged that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital cannot be fitted to Ni 3+ and Fe 2+ Characteristic peaks, indicating that the metal valence state of the commercially available iron-nickel oxide B only contains Ni 2+ and Fe 3+ The nickel iron oxide methanol oxidation reaction in Comparative Example 2 obtained 400 mA cm -2 The voltage required for the current density is 1.78V, and the oxygen evolution reaction obtains 400mAcm -2The current density required a voltage of 1.83 V, and the methanol oxidation reaction activity was lower than the oxygen evolution reaction, failing to achieve energy conservation. This indicates that commercially available nickel-iron oxide NiFe2O4 does not possess the characteristics of the nickel-iron oxide described in the present invention, and therefore does not have the corresponding electrochemical properties.

[0142] Comparative Example 3

[0143] Commercially available iron-nickel compound NiFe2O4 was purchased from Merck Reagent Company (hereinafter referred to as commercially available iron-nickel oxide compound C) and subjected to relevant Raman, in-situ infrared and electrochemical performance tests. The commercial NiFe2O4 purchased from Company C has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g =0.33. Detection of reaction intermediates during the electrooxidation of methanol by commercially available iron-nickel oxide C in Comparative Example 3: The commercially available iron-nickel oxide C in Comparative Example 3 exhibited a characteristic peak related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ), and at the same voltage, the methanol oxidation current is lower. Using the XPS test data fitting results, it can be judged that Ni 2p 1 / 2 、Fe 2p 1 / 2 , Ni 2p 3 / 2 and Fe 2p 3 / 2 The orbital cannot be fitted to Ni 3+ and Fe 2+ Characteristic peaks, indicating that the metal valence state of commercially available iron-nickel oxide C only contains Ni 2+ and Fe 3+ The nickel iron oxide methanol oxidation reaction in Comparative Example 3 obtained 400 mA cm -2 The voltage required for the current density is 1.78V, and the oxygen evolution reaction obtains 400mAcm -2 The current density required a voltage of 1.83 V, and the methanol oxidation reaction activity was lower than the oxygen evolution reaction, failing to achieve energy conservation. This indicates that commercially available nickel-iron oxide NiFe2O4 does not possess the characteristics of the nickel-iron oxide described in the present invention, and therefore does not have the corresponding electrochemical properties.

[0144] Comparative Example 4

[0145] According to the preparation method of Example 1, water-soluble nickel salt (Ni(NO3)2) was used instead of nickel foam as nickel source, and other preparation conditions were unchanged. Related Raman, in-situ infrared and electrochemical performance tests were performed. Comparative Example 4 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g =0.38. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Comparative Example 4: During the period of 1.0 V vs. RHE to 1.6 V vs. RHE voltage, a characteristic peak related to CO (located at 1900-2200 cm -1 ).like Figure 10 As shown, the nickel iron oxide methanol oxidation reaction in Comparative Example 4 obtained 400 mA cm -2 The voltage required for the current density is 1.77 V, and the oxygen evolution reaction obtains 400 mA cm -2 The current density required a voltage of 1.69V. Test results indicate that the nickel-iron oxide exhibits a lower methanol oxidation activity than the oxygen evolution reaction, lacking methanol oxidation activity and failing to achieve energy-efficient hydrogen production. The inventors believe this comparative example effectively demonstrates that the addition of an external nickel salt as a nickel source during the preparation of nickel-iron oxide does not produce the nickel-iron oxide with the characteristics and corresponding electrochemical properties described in the present invention.

[0146] Comparative Example 5

[0147] According to the preparation method of Example 1, water-soluble nickel salt (NiCl2) was used instead of nickel foam as the nickel source, and other preparation conditions remained unchanged. Relevant Raman, in-situ infrared and electrochemical performance tests were performed.

[0148] Comparative Example 5, with Raman shift = 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g=0.31. Summarizing Comparative Examples 4 and 5, it can be seen that when nickel salt is added as a nickel source during the preparation process, nickel-iron oxide with a special R value range cannot be formed, which indicates that nickel foam as the only nickel source in the present invention is a necessary condition for the formation of nickel-iron oxide with an imperfect lattice structure. Detection of reaction intermediates during the electrooxidation of methanol by the nickel-iron oxide described in Comparative Example 5: During the voltage period of 1.0 V vs. RHE to 1.6 V vs. RHE, the nickel-iron oxide described in Comparative Example 5 shows a characteristic peak for CO in the in-situ infrared spectrum (located at 1900-2200 cm -1 ) The nickel iron oxide methanol oxidation reaction in Comparative Example 5 obtained 400mA cm -2 The voltage required for the current density is 1.77 V, and the oxygen evolution reaction obtains 400 mA cm -2 The current density required a voltage of 1.69V, indicating that the nickel-iron oxide's methanol oxidation activity is lower than its oxygen evolution reaction. Comparative Example 5 demonstrates consistent results with Comparative Example 4, demonstrating that the nickel-iron oxide's methanol oxidation activity is lower than its oxygen evolution reaction, lacking methanol oxidation activity and failing to achieve energy-efficient hydrogen production. The inventors believe this comparative example also effectively demonstrates that the addition of an external nickel salt as a nickel source during the preparation of nickel-iron oxide does not produce the nickel-iron oxide with the characteristics and corresponding electrochemical properties described herein.

[0149] Comparative Example 6

[0150] According to the preparation method of Example 1, NH4Br and NaF were used instead of NH4F, and other preparation conditions were unchanged. The relevant Raman, in-situ infrared and electrochemical performance tests were carried out. Comparative Example 6 has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g =0.22. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Comparative Example 6: The nickel-iron oxide in Comparative Example 6 exhibits a characteristic peak for CO in the in-situ infrared spectrum (located at 1900-2200 cm -1 ), which shows that the NH 4+ and F - The source must be NH4F.

[0151] Comparative Example 7

[0152] According to the preparation method provided by CN 109201060 B, a nickel-iron oxide composite material was prepared by hydrothermal method and subjected to in-situ infrared and electrochemical performance tests. The tests showed that the nickel-iron oxide prepared by this method showed a CO characteristic peak (located at 1900-2200 cm -1 The nickel iron oxide methanol oxidation reaction in Comparative Example 7 obtained 400 mA cm -2 The voltage required for the current density is 1.81 V, and the oxygen evolution reaction obtains 400 mA cm -2 The current density requires a voltage of 1.75V, indicating that the methanol oxidation reaction activity of the nickel-iron oxide is lower than the oxygen evolution reaction. This shows that even if a similar preparation method, hydrothermal method, is used, it is still impossible to prepare nickel-iron oxide with anti-carbon deposition performance. The reason is that the addition of water-soluble nickel salt as a nickel source during the preparation process. The addition of water-soluble nickel salt as a nickel source will inhibit the trivalent iron ion Fe 3+ A replacement reaction occurs with the elemental Ni in the nickel foam, thereby failing to form the nickel-iron oxide of the present invention.

[0153] Comparative Example 8

[0154] According to the preparation method provided by CN 111229232A, a nickel-iron oxide composite material was prepared by hydrothermal method and subjected to in-situ infrared and electrochemical performance tests. The tests showed that the nickel-iron oxide prepared by this method showed a CO characteristic peak (located at 1900-2200cm -1 ), which shows that even using a similar preparation method, the hydrothermal method, it is still impossible to produce nickel-iron oxide with anti-carbon deposition properties. Although the patent indicates that nickel foam provides the required nickel source for the reaction, the added divalent nickel salt is the nickel source for synthesizing hydrotalcite nanosheets, so the nickel foam does not provide a nickel source for synthesizing nickel-iron oxide nanomaterials. In addition, the in-situ infrared test of this comparative example shows a CO characteristic peak, which is consistent with the results of Comparative Example 7. The nickel-iron oxide formed by the added nickel salt does not have the performance of the nickel-iron oxide of the present invention.

[0155] Comparative Example 9

[0156] According to the preparation method of Example 1, FeCl2 was used instead of Fe3(NO3)2, and other preparation conditions remained unchanged. The Raman spectroscopy test was carried out. The test results showed that the nickel iron oxide in Comparative Example 9 did not show any Raman spectroscopy in the range of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g(3), which indicates that the water-soluble divalent iron salt as an iron source cannot undergo a replacement reaction with the nickel foam, thereby failing to form nickel-iron oxide with a double Raman characteristic peak. This indicates that the water-soluble iron salt in the nickel-iron oxide provided by the present invention must be a trivalent iron salt. In-situ infrared testing and electrochemical performance testing were performed. The test showed that the nickel-iron oxide prepared by this method showed a CO characteristic peak (located at 1900-2200cm -1 ), which shows that even if a similar preparation method, hydrothermal method, is used, nickel-iron oxide with anti-carbon deposition performance cannot be prepared.

[0157] Comparative Example 10

[0158] The wt% ratio of step 1) in the preparation process of Example 1 was changed to 1:0.4:2, and the other steps remained unchanged. The prepared nickel-iron oxide had a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g =0.20. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Comparative Example 10: The nickel-iron oxide in Comparative Example 10 exhibited a characteristic peak for CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ). The nickel iron oxide methanol oxidation reaction in Comparative Example 10 obtained 100 mA cm -2 The voltage required for the current density is 1.45 V, and the oxygen evolution reaction obtains 100 mA cm -2 The current density requires a voltage of 1.44 V, which does not achieve energy-saving hydrogen production.

[0159] Comparative Example 11

[0160] The wt% ratio of step 1) in the preparation process of Example 1 was changed to 1:2:0.3, and the other steps remained unchanged. The prepared nickel-iron oxide had a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g=0.12. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Comparative Example 11: The nickel-iron oxide in Comparative Example 11 exhibited a characteristic peak for CO in the in-situ infrared spectrum (located at 1900-2200 cm -1 ).

[0161] Comparative Example 12

[0162] The hydrothermal treatment temperature in step 1) of the preparation process of Example 1 was changed to 250° C., and the other steps remained unchanged. The nickel-iron oxide prepared had a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g =0.32. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Comparative Example 12: The nickel-iron oxide in Comparative Example 12 exhibited a characteristic peak for CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ).

[0163] Comparative Example 13

[0164] The magnetization step in step 1 of the preparation process of Example 5 was removed, and the other steps remained unchanged. The prepared nickel-iron oxide had a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g =0.28. The element content analysis showed that the general formula is Ni x Fe y In O4, x=1, y=2. Figure 11 As shown, since no characteristic peak of CO was detected in the in-situ infrared spectra of Comparative Example 13 and Example 5, and considering that the materials of Example 5 and Comparative Example 13 are relatively close, the two will have similar thermogravimetric curves. Therefore, the thermogravimetric method is used to further detect whether there is carbon deposit in Comparative Example 13. According to the thermogravimetric TG test, it can be found that the weight loss of Comparative Example 13 is greater than that of Example 5, and the decrease in the thermogravimetric curve is considered to be caused by high-temperature oxidation of carbon deposits; Figure 11It can be observed that the thermogravimetric curve of Comparative Example 13 decreases more at 400°C, which indicates that the carbon deposits on the surface are oxidized, resulting in a decrease in the thermogravimetric curve. This shows that although the CO characteristic peak cannot be detected in the nickel-iron oxide prepared without the magnetization step in Example 5, the carbon deposition phenomenon still exists. If there is no carbon deposit on the surface of Comparative Example 13, a thermogravimetric curve similar to that of Example 5 will appear. Therefore, the obvious change in the thermogravimetric curve shows that the carbon deposit amount in Comparative Example 13 is significantly higher than that in Example 5.

[0165] Comparative Example 14

[0166] The magnetization time in step 1) of the preparation process of Example 1 was changed to 30s, and the other steps remained unchanged. The prepared nickel-iron oxide had a Raman shift of 500-720cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g =0.18. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Comparative Example 14: The nickel-iron oxide in Comparative Example 14 exhibited a characteristic peak for CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ).

[0167] Comparative Example 15

[0168] The heat treatment time of step 1) in the preparation process of Example 5 was changed to 1 h, and the other steps remained unchanged. The prepared nickel-iron oxide had a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g =0.18. The element content analysis showed that the general formula is Ni x Fe y In O4, x=3.2, y=1.7. Detection of the reaction intermediates during the electrooxidation of methanol by the nickel-iron oxide described in Comparative Example 15: The nickel-iron oxide described in Comparative Example 15 exhibited a characteristic peak for CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ).

[0169] Comparative Example 16

[0170] The heat treatment temperature in step 2) of the preparation process of Example 7 was changed to 600°C, and the other steps remained unchanged. The nickel-iron oxide prepared had a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g =0.11. The element content analysis showed that the general formula is Ni x Fe y In O4, x=2.2, y=1. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Comparative Example 16: The nickel-iron oxide in Comparative Example 16 exhibited a characteristic peak for CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ).

[0171] Comparative Example 17

[0172] The heat treatment time of step 2) in the preparation process of Example 7 was changed to 6 hours, and the other steps remained unchanged. The prepared nickel-iron oxide had a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), where the peak intensity I A1g and I T2g(3) Ratio R=I T2g (3) / I A1g =0.19. The element content analysis showed that the general formula is Ni x Fe y In O4, x=3.1, y=1. Detection of reaction intermediates during the electrooxidation of methanol by nickel-iron oxide in Comparative Example 17: The nickel-iron oxide in Comparative Example 17 exhibited a characteristic peak related to CO (located at 1900-2200 cm-1) in the in-situ infrared spectrum during the voltage range of 1.0 V vs. RHE to 1.6 V vs. RHE. -1 ).

[0173] It can be seen from the above embodiments and comparative examples that nickel-iron oxides prepared by conventional hydrothermal methods or by technical solutions outside the scope of the present invention do not have the structure and properties of the nickel-iron oxides described in the present invention, and cannot achieve the beneficial effects of the present invention. The nickel-iron oxide described in the present invention uses the nickel foam itself as a nickel source. The present invention sets specific magnetic field conditions. Through specific magnetization conditions and the nickel foam base, as well as the synergistic effect of all conditions such as the precise control of the raw material ratio, hydrothermal treatment temperature and time, and heat treatment temperature and time, an imperfect spinel-type nickel-iron oxide with a completely new structure of the present invention is grown in situ on the surface of the nickel foam. The spinel-type nickel-iron oxide with Raman double characteristic peaks described in the present invention has a specific general formula and a specific ratio of double characteristic peaks. The nickel-iron oxide has a special Raman characteristic peak ratio of R=I T2g (3) / I A1g ≥0.55, showing low crystallinity, the characteristics of local metal atom coordination disorder, causing the catalyst to not have a good crystal structure and ordered coordination structure in the traditional sense. However, it was unexpectedly found that the nickel-iron oxide of the present invention has excellent anti-carbon deposition ability, showing excellent alcohol catalytic activity, so that this type of nickel-iron oxide oxidation alcohol hydrogen production technology route can be applied to industrial production, with great innovation. Because the nickel-iron oxide has a unique bimetallic structure, it can effectively avoid the alcohol molecules in the hydrogen production system from being prone to carbon deposition in nickel-based materials and causing performance degradation. The nickel-iron metal oxide nanoparticles of the present invention produce a synergistic effect with the foamed nickel substrate, which can effectively improve the stability and service life of the catalyst material when the alcohol molecules are oxidized, and has many advantages such as the maintenance cost after the catalyst material is poisoned.

Claims

1. A spinel nickel-iron oxide having a Raman double characteristic peak, characterized in that: The nickel iron oxide has the general formula Ni x Fe y O4, wherein 0.5≤x≤2, 1.5≤y≤4, the Raman spectrum of the nickel-iron oxide has a Raman shift of 500-720 cm -1 There are two characteristic peaks A in the interval 1g and T 2g (3), the double characteristic peaks include peak intensity I T2g(3) The left peak and the peak intensity I A1g Right peak, the dual characteristic peak intensity ratio R = 1 T2g (3) / I A1g ≥0.55, the nickel-iron oxide contains Ni 2+ 、Ni 3+ 、Fe 2+ 、Fe 3+ .

2. Nickel-iron oxide according to claim 1, characterized in that The dual characteristic peak intensity ratio R=I T2g (3) / I A1g ≥0.

65.

3. Nickel-iron oxide according to claim 1, characterized in that The dual characteristic peak intensity ratio R=1 T2g (3) / I A1g ≥0.

75.

4. Nickel-iron oxide according to claim 1, characterized in that The dual characteristic peak intensity ratio R=I T2g (3) / I A1g ≥0.

85.

5. The nickel-iron oxide according to claim 1, characterized in that The dual characteristic peak intensity ratio R=1 T2g (3) / I A1g ≥0.

95.

6. The nickel-iron oxide according to claim 1, characterized in that The nickel iron oxide has the general formula Ni x Fe y O4, where 0.7 ≤x≤1.8, 1.7≤y≤3.

5.

7. The nickel-iron oxide according to claim 1, characterized in that The nickel iron oxide has the general formula Ni x Fe y O4, where 0.8≤x≤1.5, 1.8≤y≤3.

0.

8. The nickel-iron oxide according to claim 1, wherein The nickel iron oxide has the general formula Ni x Fe y O4, where 0.8≤x≤1.3, 1.8≤y≤2.

5.

9. The nickel-iron oxide according to claim 1, characterized in that The nickel iron oxide has the general formula Ni x Fe y O4, where 0.9≤x≤1.2, 1.9≤y≤2.

2.

10. The nickel-iron oxide according to claim 1, characterized in that The nickel iron oxide has the general formula Ni x Fe y O4, where x=0.95, y=2.

05.

11. A method for preparing the nickel-iron oxide having a Raman double characteristic peak according to any one of claims 1 to 10, characterized in that: The following steps are involved: 1) Provide Fe-containing 3+ A mixed aqueous solution of CH4N2O and NH4F is prepared, firstly placing nickel foam (Ni foam) in a magnetic field for magnetization, adding the nickel foam to the mixed aqueous solution and stirring thoroughly, and then hydrothermally treating the mixed aqueous solution and the nickel foam together to obtain a nickel-iron oxide precursor; wherein the magnetic field strength is 0.4-0.9T, the magnetization time is 5-15s, the hydrothermal treatment temperature is 85-150°C, and the hydrothermal treatment time is 3-9h; 2) heat-treating the nickel-iron oxide precursor to obtain the nickel-iron oxide with the Raman double characteristic peak, wherein the heat-treating temperature is 200-500° C. and the heat-treating time is 1-3 hours.

12. The method according to claim 11, characterized in that In the step 1), Fe 3+ The source is selected from any one or more of nitrates, sulfates and chlorides containing trivalent iron.

13. The method according to claim 11, characterized in that The magnetic field strength in step 1) is 0.5-0.8T.

14. The method according to claim 11, characterized in that The magnetic field strength in step 1) is 0.6T.

15. The method according to claim 11, characterized in that The magnetization time in step 1) is 8-12 s, more preferably 9-11 s, and more preferably 10 s.

16. The method according to claim 11, characterized in that The magnetization time in step 1) is 9-11 s.

17. The method according to claim 11, characterized in that The magnetization time in step 1) is 10 s.

18. The method according to claim 11, characterized in that In the step 1), Fe 3+ The mass fraction wt% of CH4N2O and NH4F is 1:0.8~1.2:0.8~1.

2.

19. The method according to claim 11, wherein In the step 1), Fe 3+ The mass fraction wt% of CH4N2O and NH4F is 1:0.9~1.1:0.9~1.

1.

20. The method according to claim 11, characterized in that In the step 1), Fe 3+ The mass fraction wt% of CH4N2O and NH4F is 1:0.95:1.

05.

21. The method according to claim 11, wherein In the step 1), Fe 3+ The concentration is 50-600 mg / mL.

22. The method according to claim 11, wherein In the step 1), Fe 3+ The concentration is 150-500 mg / mL.

23. The method according to claim 11, wherein In the step 1), Fe 3+ The concentration is 200-450 mg / mL.

24. The method according to claim 11, wherein In the step 1), Fe 3+ The concentration is 350mg / mL.

25. The method according to claim 11, wherein The CH4N2O in the mixed aqueous solution in step 1) is selected from any one or more of urea, thiourea, and sodium citrate containing CH4N2O, and the CH4N2O concentration is 50-600 mg / mL.

26. The method according to claim 11, wherein The CH4N2O in the mixed aqueous solution in step 1) is selected from any one or more of urea, thiourea, and sodium citrate containing CH4N2O, and the CH4N2O concentration is 150-500 mg / mL.

27. The method according to claim 11, wherein The CH4N2O in the mixed aqueous solution in step 1) is selected from any one or more of urea, thiourea, and sodium citrate containing CH4N2O, and the concentration of CH4N2O is 200-450 mg / mL.

28. The method according to claim 11, characterized in that The CH4N2O in the mixed aqueous solution in step 1) is selected from any one or more of urea, thiourea, and sodium citrate containing CH4N2O, and the CH4N2O concentration is 250-400 mg / mL.

29. The method according to claim 11, wherein In the step 1), NH4 + and F - The concentrations are 50-600 mg / mL respectively.

30. The method according to claim 11, wherein In the step 1), NH4 + and F - The concentrations are 150-500 mg / mL respectively.

31. The method according to claim 11, wherein In the step 1), NH4 + and F - The concentrations are 200-450 mg / mL respectively.

32. The method according to claim 11, wherein In the step 1), NH4 + and F - The concentrations are 250-400 mg / mL respectively.

33. The method according to claim 11, wherein In the step 1), the temperature of the hydrothermal treatment is 100-135°C.

34. The method according to claim 11, wherein In the step 1), the temperature of the hydrothermal treatment is 125°C.

35. The method according to claim 11, wherein In the step 1), the hydrothermal treatment time is 5 to 7 hours.

36. The method according to claim 11, wherein In the step 1), the hydrothermal treatment time is 5.5 hours.

37. The method according to claim 11, wherein In the step 2), the heat treatment temperature is 300-400°C.

38. The method according to claim 11, wherein In the step 2), the heat treatment temperature is 340°C.

39. The method according to claim 11, wherein In the step 2), the heat treatment time is 2.5 hours.

40. The method according to claim 11, wherein In the step 2), the heat treatment atmosphere is any one or more of nitrogen, argon, and hydrogen-argon.

41. The method according to claim 11, wherein In the step 2), the heat treatment atmosphere is any one or more of nitrogen and argon.

42. The method according to claim 11, wherein In the step 2), the atmosphere of the heat treatment is argon.

43. A catalyst, characterized in that The catalyst comprises the nickel-iron oxide according to any one of claims 1 to 10 or the nickel-iron oxide prepared by the method according to any one of claims 11 to 42.

44. Use of the catalyst according to claim 43 in a chemical reaction.

45. Use of the catalyst according to claim 43 in a hydrogen production reaction.

46. ​​A hydrogen production system, characterized in that The hydrogen production system comprises the nickel-iron oxide according to any one of claims 1 to 10 or the nickel-iron oxide prepared by the method according to any one of claims 11 to 42 as a catalyst for the hydrogen production reaction, an external oxidation substrate, and an electrolysis device.

47. A hydrogen production system according to claim 46, characterized in that: The external oxidation substrate in the system is selected from any one of an alcohol substance, a substance containing CON2H4, and a substance containing NH3·H2O.

48. A hydrogen production system according to claim 47, characterized in that: The alcohol substance in the system is selected from any one or more of methanol, ethanol, and isopropanol.

49. A hydrogen production system according to claim 47, characterized in that: The alcohol substance in the system is any one or more of methanol and isopropanol.

50. A hydrogen production system according to claim 47, characterized in that: The alcohol substance in the system is methanol.

51. A hydrogen production system according to claim 47, characterized in that: The substance containing NH3·H2O in the system is urea.

52. A hydrogen production system according to claim 47, characterized in that: The substance containing CON2H4 in the system is ammonia water.

53. The hydrogen production system according to claim 47, characterized in that The mass fraction of the added oxidation substrate in the hydrogen production reaction electrolyte is 5-30 wt%.

54. The hydrogen production system according to claim 47, characterized in that The mass fraction of the added oxidation substrate in the hydrogen production reaction electrolyte is 10-25 wt%.

55. The hydrogen production system according to claim 47, characterized in that The mass fraction of the added oxidation substrate in the hydrogen production reaction electrolyte is 15-20 wt%.

56. The hydrogen production system according to claim 47, characterized in that The mass fraction of the added oxidation substrate in the hydrogen production reaction electrolyte is 17 wt%.

57. A method for preparing hydrogen, characterized in that: The general reaction formula is as follows: In the formula, the nickel-iron oxide is the nickel-iron oxide according to any one of claims 1 to 10 or the nickel-iron oxide prepared by the method according to claim 11.

58. A method according to claim 57, characterized in that The pH value in the method is >10.

59. A method according to claim 57, characterized in that No CO or carbon deposits are generated in the method.

60. A method according to claim 57, characterized in that The external oxidation substrate is selected from any one of an alcohol substance, a substance containing CON2H4, and a substance containing NH3·H2O.

61. A method according to claim 60, characterized in that The alcohol substance is selected from any one or more of methanol, ethanol, and isopropanol.

62. A method according to claim 60, characterized in that The alcohol substance is selected from any one or more of methanol and isopropanol.

63. A method according to claim 60, characterized in that The alcohol substance is methanol.

64. A method according to claim 60, characterized in that The substance containing CON2H4 is urea.

65. A method according to claim 60, characterized in that The substance containing NH3·H2O is ammonia water.

66. A method according to claim 60, characterized in that The mass fraction of the alcohol substance in the hydrogen production reaction electrolyte is 5-30 wt%.

67. A method according to claim 60, characterized in that The mass fraction of the alcohol substance in the hydrogen production reaction electrolyte is 10-25 wt%.

68. A method according to claim 60, characterized in that The mass fraction of the alcohol substance in the hydrogen production reaction electrolyte is 15-20 wt%.

69. A method according to claim 60, characterized in that The mass fraction of the alcohol substance in the hydrogen production reaction electrolyte is 17 wt%.

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