An oxygen-deficient iron / tin heterojunction nano-electrocatalytic material and its preparation method and application

Abstract

The present invention discloses an oxygen-deficient iron / tin heterojunction nano-electrocatalytic material and its preparation method and application, belonging to the technical field of electrocatalytic materials. The preparation method comprises: (1) pre-treating nickel foam, adding the nickel foam to a mixed solution of iron salt, terephthalic acid, deionized water and an organic solvent, and performing a hydrothermal reaction at 100-150°C for 15-30 hours to obtain a precursor; (2) constructing a reaction system comprising the precursor of step (1), tin salt, sodium citrate and ethanol aqueous solution, placing the reaction system at 150-210°C for a hydrothermal reaction for 6-18 hours, and annealing the obtained product at 400-600°C under an inert gas atmosphere for 3-6 hours to obtain the oxygen-deficient iron / tin heterojunction nano-electrocatalytic material. The electrocatalytic material has good catalytic activity and high durability, and can be used as an electrocatalytic anode material based on LOM.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic materials, and in particular relates to an oxygen-deficient iron / tin heterojunction nano-electrocatalytic material and a preparation method and application thereof. Background Art

[0002] Today's society has a huge demand for energy, while traditional fossil fuel reserves are limited. Developing a new fuel energy source that can replace traditional fossil fuels with cleaner, more efficient, and cheaper alternatives has become a critical issue that demands urgent attention, and its urgency cannot be ignored. Hydrogen, as a renewable energy source, is widely available and can be produced through various methods such as water electrolysis, natural gas reforming, and biomass conversion. Hydrogen also offers advantages such as environmental friendliness, zero carbon emissions, and high energy density. It is considered one of the most critical new fuel energy sources for energy transformation.

[0003] Using natural energy sources (solar, wind, tidal, etc.) to generate clean electricity and electrochemically catalytically produce hydrogen from water is a key step in realizing hydrogen energy applications. Typically, electrocatalytic hydrogen production requires the complete decomposition of water, which involves the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. The OER at the conventional anode follows the adsorption evolution mechanism (AEM), which involves four slow electron transfer steps. The generation of three key intermediates (adsorbed oxygen, adsorbed hydroxyl groups, and adsorbed peroxide ions) presents significant energy barriers (with a theoretical minimum overpotential limit of 370 mV), significantly reducing the efficiency and economic benefits of electrocatalytic hydrogen production. To address this issue, scientists have proposed leveraging the activation of lattice oxygen in anode catalysts to participate in the redox reaction in the OER, triggering the OER and following the lattice oxygen evolution mechanism (LOM). This approach circumvents the limitations of the AEM, lowers the energy barrier, and improves the efficiency and economic benefits of electrocatalytic hydrogen production.

[0004] For example, Chinese patent publication CN118127559A discloses a high-valent metal-doped Co4N catalyst. Its preparation method includes: hydrothermal synthesis of Mn-doped cobalt nanowires uniformly grown on a nickel foam substrate, followed by nitridation to obtain Mn-doped Co4N nanowires grown on the nickel foam. These nanowires are then used as electrode materials, and their surfaces are reconstructed using cyclic voltammetry to ultimately produce a Mn-doped CoO2 / Co4N composite material. The Mn can regulate the upward shift of the oxygen 2P orbital beyond the Fermi level, thereby activating the lattice oxygen on the catalyst surface, allowing it to participate in the reaction and ultimately inducing the lattice oxygen reaction pathway.

[0005] The results of existing research indicate that increasing the covalency of metal-oxygen (MO) bonds is the key to triggering the lattice oxygen oxidation reaction. (LOM)), researchers have tried many modification strategies, such as constructing heterojunctions, defect engineering, band regulation, and co-catalyst modification. Among them, constructing heterojunction materials has been proven to be a very promising method, which not only captures electrons from catalytic materials to suppress charge recombination, but also provides sufficient active sites to accelerate the catalytic reaction rate. At the same time, OER (LOM) It is necessary to utilize a large number of oxygen vacancies (Ov) on the surface of the material as reaction space, and it is also crucial to use defect engineering to increase the Ov on the surface of the material.

[0006] However, in OER (LOM) The process will produce unsaturated MO adsorption sites, causing the leaching of metal species on the surface, which leads to a generally short service life of electrocatalytic materials. Therefore, the development of robust and durable OER (LOM) Electrocatalysts have become a research hotspot in the field of electrochemical catalytic materials technology. Summary of the Invention

[0007] The present invention provides a method for preparing an oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material. The method is simple, efficient, easy to implement, and has relatively mild reaction conditions. The prepared oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material has good conductivity and catalytic activity, high durability, and abundant surface Ov. It can be used as an electrocatalytic anode material based on LOM and has good potential application value.

[0008] The specific technical solutions adopted are as follows:

[0009] A method for preparing an oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material, wherein the oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material can be represented as Fe2O3@SnO2-Ov / NF, where Ov represents oxygen vacancies on the surface of the material. The method comprises the following steps:

[0010] (1) After pre-treating nickel foam, add it to a mixed solution of iron salt, terephthalic acid, deionized water and organic solvent, and perform hydrothermal reaction at 100-150 °C for 15-30 hours to obtain a precursor; the precursor includes MIL-53 (Fe) grown on the nickel foam substrate;

[0011] (2) Constructing a reaction system comprising the precursor of step (1), tin salt, sodium citrate and ethanol aqueous solution, subjecting the reaction system to a hydrothermal reaction at 150-210°C for 6-18 hours, and annealing the obtained product at 400-600°C under an inert gas atmosphere for 3-6 hours to prepare the oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material.

[0012] The present invention combines Fe2O3 with SnO2, which is helpful for developing durable, low-cost and high-performance electrocatalytic materials. On the one hand, the presence of Fe can induce the downward shift of the metal d band to penetrate the 2p band of the oxygen ligand, increase the covalency of metal-oxygen (MO), thereby triggering the LOM path of OER and inhibiting the dissolution of metal substances. On the other hand, Sn has a high electronegativity (1.96), which is also one of the key factors for enhancing the covalency of MO. The synergistic effect of Fe and Sn elements enhances the covalency of MO bonds, and SnO2 also has strong catalytic performance. Incorporating SnO2 into iron-based materials and constructing heterojunctions can greatly improve the LOM electrocatalytic performance of the material. Furthermore, after high-temperature annealing, the SnO2 crystal loses a large number of oxygen atoms to form rich surface Ov, and can itself form electronic defects and Sn 4+ The vacancy pairs maintain the integrity of the crystal structure, which also provides a basis for the OER (LOM) Provide sufficient reaction space, enhance the catalytic activity of the material, and maximize its application potential.

[0013] Preferably, the pretreatment step of the nickel foam comprises: washing the nickel foam in deionized water, dilute hydrochloric acid and anhydrous ethanol respectively, and storing the nickel foam in anhydrous ethanol after washing for future use to prevent oxidation.

[0014] Specifically, in step (1), the organic solvent is selected from N,N-dimethylformamide (DMF) and anhydrous ethanol, and the volume ratio of N,N-dimethylformamide, anhydrous ethanol and deionized water is 9-18:1:1.

[0015] Preferably, in step (1), the amount of iron salt added is controlled to be Fe 3+ The content is 1-2 mM, terephthalic acid and Fe 3+ The molar mass ratio is 1-2:1.

[0016] Most preferably, in step (1), the hydrothermal reaction conditions are 125° C. and 24 hours.

[0017] Preferably, after the precursor is prepared, it is rinsed three times with oxygen-free deionized water and then vacuum dried. After drying, it is placed in a vacuum cover for vacuum storage for later use.

[0018] Preferably, in step (2), the amount of tin salt added is controlled to be Sn per 40 ml of ethanol aqueous solution. 2+ The content of Fe in the precursor is 0.5-1mM; 3+ , Sn in tin salts 2+ The molar mass ratio of sodium citrate to sodium citrate is 2:1-2:1-4.

[0019] Most preferably, in step (2), the hydrothermal reaction conditions are 180° C. and 12 hours.

[0020] Optionally, the inert gas atmosphere is an argon atmosphere, the heating rate during annealing is 5-10° C. / min, and the most preferred calcination conditions are 500° C. and 3 hours.

[0021] More preferably, the iron salt is ferric nitrate, and the tin salt is stannous chloride.

[0022] Preferably, the oxygen-deficient iron / tin heterojunction nano-electrocatalytic material is rinsed with oxygen-free deionized water and then vacuum-dried after preparation. After drying, it is placed in a vacuum cover for vacuum storage.

[0023] The present invention also provides an oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material prepared by the preparation method of the oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material, wherein oxygen-deficient heterojunction nanosheets composed of Fe2O3 and SnO2 are orderly grown on a foam nickel substrate.

[0024] The present invention also provides the use of the oxygen-deficient iron / tin heterojunction nano-electrocatalytic material in water electrolysis.

[0025] The present invention also provides a method for electrolyzing water, which uses the oxygen-deficient iron / tin heterojunction nano-electrocatalytic material.

[0026] Preferably, the oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material is pressed into a tablet at a pressure of 10-20 MPa and then used as an anode working electrode in the OER reaction. Pressing the tablet gives the electrode greater plasticity, while unpressed tablets would have a large volume and affect overall conductivity.

[0027] Fe2O3@SnO2-Ov / NF as the anode successfully captured O2 unique to the LOM pathway during the hydrogen evolution reaction of water electrolysis. 2- The results show that the OER process of this electrode successfully triggers the LOM mechanism. Currently, most hydrogen production anodes on the market are RuO2 electrodes. However, under the condition of the same electrode area, the electrocatalytic efficiency and hydrogen evolution kinetics of the Fe2O3@SnO2-Ov / NF electrode are much stronger than those of the RuO2 electrode, and it also has strong stability.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The oxygen-deficient iron / tin heterojunction nano-electrocatalytic material prepared by the method of the present invention is a kind of material that can induce OER. (LOM) The anode catalytic material can circumvent the limitations of AEM, lower the energy barrier, and improve the efficiency and benefits of electrocatalytic hydrogen production.

[0030] (2) The oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material obtained by the present invention through a simple synthesis route can be directly used as an electrocatalytic anode material; based on the transition metal element iron, the Fe2O3@SnO2 heterojunction is in situ grown on nickel foam, achieving a simultaneous improvement in the durability and electrocatalytic performance of the electrocatalytic material; at the same time, defect engineering is used to create abundant Ov on the surface of the heterojunction material, promoting the triggering of the LOM pathway of OER and reducing the energy barrier of OER. When used as an anode material for simulated electrochemical hydrogen production, the Fe2O3@SnO2-Ov / NF electrode has the advantages of long service life, high catalytic efficiency, and low energy consumption; it alleviates the problem of the generally short service life of electrocatalytic materials caused by the leaching of metal substances on the surface.

[0031] (3) The oxygen-deficient iron / tin heterojunction nano-electrocatalytic material prepared by the method of the present invention has good electrocatalytic performance, high durability and rich Ov after being pressed into electrodes, and has a low Tafel reaction step energy barrier, which has the potential to become a practical OER (LOM) Potential of electrocatalytic anodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 (a) is the XRD pattern of the precursor MIL-53(Fe), and (b) is the XRD pattern of Fe2O3@SnO2-Ov in Example 1, Fe2O3@SnO2 in Comparative Example 4, Fe2O3 in Comparative Example 2, and SnO2 in Comparative Example 3.

[0033] Figure 2 Surface SEM images of electrocatalytic materials of different products are shown in FIG. 1 , where (a) is Example 1, (b) is Comparative Example 2, and (c) is Comparative Example 3.

[0034] Figure 3 The EPR spectra of the sample electrodes prepared in Example 1 and different comparative examples are shown.

[0035] Figure 4 The LSV cycle diagrams of the sample electrodes prepared in Example 1 and different comparative examples.

[0036] Figure 5 The Tafel energy barrier diagrams of the sample electrodes prepared in Example 1 and different comparative examples.

[0037] Figure 6 This is a stability test diagram of the Fe2O3@SnO2-Ov / NF electrode prepared in Example 1. DETAILED DESCRIPTION

[0038] In order to make the objects, features and advantages of the present invention more clearly understood, a detailed description is given below using specific embodiments. In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. The technical features in the various embodiments of the present invention can be combined accordingly without conflicting with each other.

[0039] The procedures for the following examples, in which specific conditions are not specified, generally follow conventional conditions or those recommended by the manufacturer. Any material not described in detail in this specification belongs to the prior art known to those skilled in the art. The experimental materials used in the following examples, unless otherwise specified, can be purchased from conventional biochemical reagent companies.

[0040] Example 1

[0041] (1) Preparation of fresh nickel foam (NF) substrate:

[0042] The 2 mm thick NF was cut into sheets with a length of 4 cm and a width of 3.5 cm. The sheets were first ultrasonically cleaned in deionized water for 30 minutes, and then ultrasonically pickled with dilute hydrochloric acid (37% concentrated hydrochloric acid and deionized water diluted in a volume ratio of 1:3) for 120 minutes. After pickling, the sheets were simply filtered and washed in 500 ml deionized water for 10 seconds. Finally, they were thoroughly washed with anhydrous ethanol and stored in anhydrous ethanol for later use.

[0043] (2) Preparation of MIL-53(Fe) / NF intermediate:

[0044] 1 mM Fe(NO3)3 and 1 mM terephthalic acid (TPA) were mixed evenly and poured into 35 ml N,N-dimethylformamide (DMF) and stirred for 60 minutes. Then, 2.5 ml of anhydrous ethanol and 2.5 ml of deionized water were added and stirred for 60 minutes to obtain a mixed solution. The mixed solution was poured into a high-pressure reactor, and the fresh NF prepared in step (1) was added and allowed to stand for 5 minutes. After the NF was fully in contact with the solution, the reactor was tightened. The reactor was placed in a constant temperature oven and hydrothermally reacted at 125°C. After 24 hours of reaction, the reactor was taken out and naturally cooled to room temperature. The reaction product was then taken out and thoroughly washed with deionized water. After vacuum drying at 60°C, the thin sheet material MIL-53(Fe) / NF was obtained.

[0045] (3) Preparation of Fe2O3@SnO2 / NF:

[0046] 0.5 mM SnCl2 and 0.9175 mM sodium citrate were mixed evenly and poured into 40 ml of ethanol-water solution (the volume ratio of ethanol to water was 1:1) and stirred for 60 minutes. The mixed solution was poured into a high-pressure reactor, and the MIF-53(Fe) / NF prepared in step (2) was added and allowed to stand for 5 minutes. After the MIF-53(Fe) / NF was fully in contact with the solution, the reactor was tightened. The reactor was placed in a constant temperature oven and hydrothermally reacted at 180°C. After 12 hours of reaction, the reactor was removed and cooled naturally to room temperature. The material was then removed and thoroughly washed with deionized water. After vacuum drying at 60°C, the thin-sheet material Fe2O3@SnO2 / NF was obtained.

[0047] (4) Preparation of Fe2O3@SnO2-Ov / NF:

[0048] Fe2O3@SnO2 / NF was placed in a tube furnace and heated to 500°C at a rate of 5°C / min under a continuous flow of argon. After high-temperature annealing for 3 hours, the oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material Fe2O3@SnO2-Ov / NF was obtained.

[0049] (5) Preparation of working electrode:

[0050] The Fe2O3@SnO2-Ov / NF obtained in step (4) was subjected to tableting treatment at a pressure of 10.0 MPa to obtain a Fe2O3@SnO2-Ov / NF electrode.

[0051] Comparative Example 1

[0052] The NF sheet without any material loaded was used as the sample of Comparative Example 1.

[0053] Comparative Example 2

[0054] The pressed Fe2O3 / NF sheet material was used as the sample of Comparative Example 2, denoted as the Fe2O3 / NF electrode. The preparation method of the Fe2O3 / NF in this comparative example differed from the preparation method of the MIL-53(Fe) / NF in the example only in that the hydrothermal reaction temperature was 180°C.

[0055] Comparative Example 3

[0056] 0.5 mM SnCl₂ and 0.9175 mM sodium citrate were mixed and poured into 40 ml of ethanol-water solution (ethanol:water ratio:1:1 by volume) and stirred for 60 minutes. The mixed solution was then poured into an autoclave, and fresh NF was added. The autoclave was tightened after the NF was fully exposed to the solution. The autoclave was placed in a constant temperature oven and a hydrothermal reaction was carried out at 180°C. After 12 hours of reaction, the autoclave was removed and allowed to cool naturally to room temperature. The material was then removed, rinsed thoroughly with deionized water, and vacuum dried at 60°C to obtain a SnO₂ / NF thin sheet. The pressed SnO₂ / NF thin sheet was used as the sample of Comparative Example 3, designated as the SnO₂ / NF electrode.

[0057] Comparative Example 4

[0058] The Fe2O3@SnO2 / NF prepared in step (3) of Example 1 after tableting was used as the sample of Comparative Example 4, and was recorded as Fe2O3@SnO2 / NF electrode.

[0059] Comparative Example 5

[0060] A conventional commercial RuO2 electrode was used as the sample of Comparative Example 5.

[0061] Sample analysis

[0062] The samples of the above examples and comparative examples were subjected to electrochemical hydrogen evolution tests in the following manner:

[0063] Electrochemical hydrogen evolution tests were conducted using a Shanghai Chenhua electrochemical workstation, using a 1 mol / L KOH solution as the electrolyte, an Ag / AgCl electrode as the reference electrode, a stainless steel electrode as the counter electrode, and the sample electrodes prepared in the Examples and Comparative Examples as the working electrode. The electrolyte was first purged with nitrogen for 30 minutes before the electrochemical hydrogen evolution performance test was performed.

[0064] The overpotential of the electrochemical test of each embodiment and comparative example (current density reaches 10 mA / cm 2 ) See Table 1 for details.

[0065] Table 1 Electrochemical hydrogen evolution test results

[0066]

[0067] As shown in Table 1, the Fe2O3@SnO2-Ov / NF sample of Example 1 exhibits the best performance, with a lower overpotential than the Fe2O3@SnO2 / NF sample of Comparative Example 3 and the traditional commercial RuO2 electrode, confirming the enhanced electrocatalytic performance of the abundant Ov and its promising potential for industrial application. The sample of Comparative Example 4 exhibits a lower overpotential than the Fe2O3 / NF samples and SnO2 / NF samples of Comparative Examples 2 and 3, confirming the synergistic effect of Fe and Sn on electrocatalytic performance.

[0068] Figure 1 (a) is the XRD pattern of MIL-53(Fe), and (b) is the XRD pattern of Fe2O3@SnO2-Ov in Example 1, Fe2O3@SnO2 in Comparative Example 4, Fe2O3 in Comparative Example 2, and SnO2 in Comparative Example 3. Figure 1 (a) shows the successful synthesis of the MIL-53(Fe) precursor in step (2) of the example; Figure 1 (b) shows that the electrodes of Example 1 and Comparative Example 4 have XRD signals of both Fe2O3 and SnO2, indicating that they are coupled products of two metal oxides, indicating the successful formation of Fe2O3@SnO2 heterojunction electrodes; Figure 1 (b) also shows that the electrodes of Comparative Examples 2 and 3 have XRD signals of Fe2O3 and SnO2, respectively, and are high-purity items of a single metal, indicating that the electrodes of Comparative Examples 2 and 3 are successfully formed.

[0069] Figure 2 The surface SEM images of the Fe2O3@SnO2-Ov / NF heterojunction electrode in Example 1 and the Fe2O3 / NF and SnO2 / NF electrodes in Comparative Examples 2 and 3 are shown. The electrodes of Comparative Examples 2-3 were characterized at different magnifications using SEM. Figure 2 (b) and Figure 2 The SEM image in (c) clearly shows that the Fe2O3 and SnO2 on the electrode present "nano-sheet" and "nano-sphere" morphologies respectively. The electrode of Example 1 was characterized by SEM at different magnifications. Figure 2 The SEM image in (a) clearly shows the two morphologies of nanosheet Fe2O3 and nanospherical SnO2, and the nanospherical SnO2 forms a tight fit with the nanosheet Fe2O3, confirming the formation of the Fe2O3@SnO2 heterojunction structure.

[0070] Figure 3 EPR characterization images of the Fe2O3@SnO2-Ov / NF electrode prepared in Example 1, the Fe2O3 / NF electrode prepared in Comparative Example 2, the SnO2 / NF electrode prepared in Comparative Example 3, and the Fe2O3@SnO2 / NF electrode prepared in Comparative Example 4. The signal peak at g = 2.003 for the Fe2O3@SnO2-Ov / NF electrode is significantly stronger than that of the other electrodes, indicating that this electrode has the most Ov on its surface, indicating its strong electrocatalytic potential.

[0071] Figure 4The LSV curves of the Fe2O3@SnO2-Ov / NF electrode prepared in Example 1, the NF electrode prepared in Comparative Example 1, the Fe2O3 / NF electrode prepared in Comparative Example 2, the SnO2 / NF electrode prepared in Comparative Example 3, the Fe2O3@SnO2 / NF electrode prepared in Comparative Example 4, and the traditional commercial RuO2 electrode in Comparative Example 5 are shown, with MIL-53(Fe) / NF used as a comparison. Among them, the overpotential of the electrode in Example 1 is significantly lower than that of the electrodes in other comparative examples, indicating its excellent hydrogen evolution performance, confirming the synergistic effect of Sn and Fe and the improvement of electrocatalytic performance by a large amount of Ov on the surface. At the same time, it shows that the catalytic performance of the Fe2O3@SnO2-Ov / NF electrode prepared in the present invention is much higher than that of the traditional commercial RuO2 electrode, and has good application prospects.

[0072] Figure 5 The Tafel slope plots for the Fe2O3@SnO2-Ov / NF electrode prepared in Example 1, the Fe2O3 / NF electrode prepared in Comparative Example 2, the SnO2 / NF electrode prepared in Comparative Example 3, the Fe2O3@SnO2 / NF electrode prepared in Comparative Example 4, and the traditional commercial RuO2 electrode in Comparative Example 5 are shown. The j on the abscissa represents the current density. The Fe2O3@SnO2-Ov / NF electrode has the lowest slope of 57.5 mV / dec, promoted by the synergistic effect of Sn and Fe and the large amount of Ov on its surface, indicating its good hydrogen evolution kinetics.

[0073] Figure 6 The stability test of the Fe2O3@SnO2-Ov / NF electrode prepared in Example 1 was conducted. Under the working condition of a voltage of 1.5 V, the electrode continued to work for 120 hours, and its current density changed from 106.68 mA to 93.84 mA, maintaining 88% of the starting current, indicating that the catalytic performance of the electrode is still good, basically meeting the market demand for electrode materials.

[0074] In summary, the use of defect engineering to synthesize the oxygen vacancy-rich heterojunction electrocatalytic anode material Fe2O3@SnO2-Ov and load it on nickel foam has demonstrated the potential for efficient and stable hydrogen production. Currently, most hydrogen production anodes on the market are RuO2 electrodes. Under the same electrode area, the electrocatalytic efficiency and hydrogen evolution kinetics of Fe2O3@SnO2-Ov / NF electrode are much stronger than those of RuO2 electrode. When the current density reaches 10 mA / cm 2When the overpotential of the Fe2O3@SnO2-Ov / NF electrode is only 171 mV, while the overpotential of the commercial RuO2 electrode is as high as 367 mV. In addition, the lowest Tafel slope of the Fe2O3@SnO2-Ov / NF is 57.5 mV / dec, while the Tafel slope of the commercial RuO2 electrode is as high as 102 mV / dec. At the same time, the Fe2O3@SnO2-Ov / NF electrode can maintain a current density of 93-106 mA / cm at a constant potential of 1.5 V. 2 It can work continuously for 120 hours with only minor current fluctuations and degradation, which basically meets the requirements of commercial hydrogen production.

[0075] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing an oxygen-deficient iron / tin heterojunction nano-electrocatalytic material, characterized in that: The following steps are involved: (1) After pre-treating nickel foam, add it to a mixed solution of iron salt, terephthalic acid, deionized water and organic solvent, and perform hydrothermal reaction at 100-150 °C for 15-30 hours to obtain a precursor; the precursor includes MIL-53 (Fe) grown on the nickel foam substrate; (2) constructing a reaction system comprising the precursor of step (1), tin salt, sodium citrate and ethanol aqueous solution, subjecting the reaction system to a hydrothermal reaction at 150-210°C for 6-18 hours, and annealing the obtained product at 400-600°C under an inert gas atmosphere for 3-6 hours to prepare the oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material; The iron salt is ferric nitrate, and the tin salt is stannous chloride; In step (1), the organic solvent is selected from N,N-dimethylformamide and anhydrous ethanol, and the volume ratio of N,N-dimethylformamide, anhydrous ethanol and deionized water is 9-18:1:1; In step (1), the amount of iron salt added is controlled to be Fe 3+ The content is 1-2 mM, terephthalic acid and Fe 3+ The molar mass ratio is 1-2: 1; In step (2), the amount of tin salt added is controlled to be Sn per 40 ml of ethanol aqueous solution. 2+ The content of Fe in the precursor is 0.5-1 mM; 3+ , Sn in tin salts 2+ The molar mass ratio of sodium citrate to sodium citrate is 2:1-2:1-4; The inert gas atmosphere was an argon atmosphere.

2. The method for preparing the oxygen-deficient iron / tin heterojunction nano-electrocatalytic material according to claim 1, characterized in that: The pretreatment steps of the nickel foam include: washing the nickel foam in deionized water, dilute hydrochloric acid and anhydrous ethanol respectively.

3. The method for preparing the oxygen-deficient iron / tin heterojunction nano-electrocatalytic material according to claim 1, characterized in that: The heating rate during annealing is 5-10°C / min.

4. An oxygen-deficient iron / tin heterojunction nano-electrocatalytic material prepared according to the method for preparing an oxygen-deficient iron / tin heterojunction nano-electrocatalytic material according to any one of claims 1 to 3.

5. Use of the oxygen-deficient iron / tin heterojunction nano-electrocatalytic material according to claim 4 in water electrolysis.

6. A method for electrolyzing water, characterized in that: The oxygen-deficient iron / tin heterojunction nano-electrocatalytic material according to claim 4 is pressed into tablets and used as an anode material.

Images