A medium-entropy metal chalcogenide, a preparation method and application thereof

Abstract

The application discloses a medium-entropy metal telluride and a preparation method and application thereof, specifically, metal salt and fumaric acid are used in an N,N-dimethylformamide solvent environment, so that metal ions and carboxyl groups are fully contacted and coordinated to construct a metal-organic complex precursor solution; the precursor solution is reacted at a specific temperature to make the metal-organic complex molecules undergo a complex chemical rearrangement and bonding process to form an ordered crystal structure, namely Fe2(CoNi)-MOF; the Fe2(CoNi)-MOF and tellurium powder are calcined at a high temperature in a H2 / Ar mixed gas to generate a series of synergistic reactions to generate the medium-entropy metal telluride. The medium-entropy metal telluride prepared by the application has high efficient catalytic hydrogen evolution and oxygen evolution potential in a water electrolysis hydrogen production reaction, can greatly improve the catalytic efficiency and reaction kinetic characteristics, and is used for preparing a water electrolysis hydrogen production catalyst.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of catalyst preparation, in particular to a medium-entropy metal telluride and a preparation method and application thereof. BACKGROUND

[0002] The catalysts for hydrogen production reactions are generally catalysts of noble metals, but the catalysts of noble metals have high cost, limited resources and poor stability, which limits their large-scale application. Therefore, seeking efficient, stable and low-cost catalyst materials has been the focus of research in the field of water electrolysis hydrogen production reaction catalyst technology. Metal-organic framework (MOF) materials have attracted wide attention in the field of catalyst preparation due to their unique structural characteristics, such as good coordination environment, structural flexibility and composition adjustability. However, the traditional MOF materials still have problems such as limited number of active sites, insufficient intrinsic conductivity and high reaction energy barrier in some catalytic reactions, and cannot completely replace noble metal catalysts. Therefore, it is urgent to develop a new type of non-noble metal material for preparing catalyst materials, which has excellent catalytic activity and high stability. SUMMARY

[0003] The purpose of the application is to develop a non-noble metal catalyst material with excellent overall water splitting performance and cycle stability for preparing a water hydrogen production catalyst.

[0004] The application embodiment discloses a medium-entropy metal telluride, which is a multi-metal MOF constructed based on two or more medium-entropy metal ions and organic ligands, and is a material obtained by high-temperature calcination reaction of the multi-metal MOF and tellurium powder.

[0005] Preferably, the medium-entropy metal ions are three, namely Fe+, Co+ and Ni+.

[0006] Preferably, the organic ligand is fumaric acid.

[0007] The application embodiment also discloses a preparation method of the medium-entropy metal telluride, and the specific preparation method comprises the following steps:

[0008] S1 a certain amount of iron nitrate nonahydrate, cobalt nitrate hexahydrate, nickel nitrate hexahydrate and fumaric acid are dissolved in N,N-dimethylformamide, and fully stirred and uniformly mixed;

[0009] S2 the obtained solution is placed in an oven for reaction for a period of time, the reaction product is centrifuged, washed and dried at 40 DEG C for 8 hours to obtain a Fe2(CoNi)-MOF three-element metal-organic framework;

[0010] S3 will be obtained by calcining the above obtained Fe2(CoNi)-MOF and tellurium powder in a certain ratio in H2 / Ar mixed gas at high temperature for a certain time to obtain the final iron-cobalt-nickel three-element metal-organic framework telluride derivative (Fe2(CoNi)Te x )。

[0011] Preferably, in the step S1, the molar mass of the iron nitrate nonahydrate is 1.67-2.5 mmol, the molar mass of the cobalt nitrate hexahydrate is 1.25-1.67 mmol, the molar mass of the nickel nitrate hexahydrate is 1.25-1.67 mmol, the molar mass of the fumaric acid is 40-50 mmol, and the molar mass of the N,N-dimethylformamide is 40-50 ml.

[0012] Preferably, in the step S1, the stirring process is stirring at room temperature for 30 min, and the stirring speed is 200 rpm.

[0013] Preferably, in the step S2, the solution reaction temperature is 100-120℃, and the reaction time is 8-10 h.

[0014] Preferably, in the step S2, the centrifugation time is 3-5 min, the centrifugation speed is 8000 rpm, and after centrifugation, the product is first washed once with water and then washed three times with anhydrous ethanol.

[0015] Preferably, in the step S3, the mass ratio of Fe2(CoNi)MOF to tellurium powder is 1:0.8-1.2, the calcination temperature is 500℃-800℃, and the heat treatment time is 8-12 h.

[0016] The application also provides an application of the medium-entropy metal telluride, which is used for preparing a water hydrogen production catalyst and can greatly improve the catalytic efficiency.

[0017] The application has the advantages that the magnetic iron, cobalt and nickel nanoparticles exhibit high activity in the catalytic process of hydrogen evolution and oxygen evolution reactions, have higher configuration energy, excellent mechanical stability and corrosion resistance compared with traditional alloys, which ensures the stability of the chemical composition of the catalyst prepared from the three metal elements in an alkaline electrolyte. After the MOF precursor is converted into the medium-entropy metal telluride, the d-band center of the metal site is close to the Fermi level, which improves the adsorption / desorption of H by the electrocatalyst and significantly reduces the rate-determining step of the Gibbs free energy. The tellurium powder is used as a tellurium source, and the pyrolysis metal active species are generated by atomic diffusion and chemical bond reorganization to form Fe2(CoNi)Tex, realize the key conversion from the MOF precursor to the metal telluride, reshape the electronic structure of the material, enrich the active sites, optimize the catalytic performance, endow the material with high-efficiency catalytic hydrogen evolution and oxygen evolution potential in the water electrolysis hydrogen production reaction, greatly improve the catalytic efficiency and reaction kinetic characteristics, and can be used for preparing a hydrogen production catalyst material to provide material support for solving the energy bottleneck of water electrolysis hydrogen production. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The image shows the X-ray diffraction pattern of the Fe2(CoNi)-MOF prepared in Example 1.

[0020] Figure 2 The image shown is a TEM image of the Fe2(CoNi)-MOF and Fe2(CoNi)Te materials prepared in Example 1.

[0021] Figure 3 The figures shown are Fe2(CoNi)Te prepared in Examples 1-3. x X-ray diffraction patterns of x = 0.8, 1, 1.2.

[0022] In the picture: Figure 2 (a) TEM image of Fe2(CoNi)-MOF material; 2(b) TEM image of Fe2(CoNi)Te material; 2(c) HRTEM image of Fe2(CoNi)Te material; 2(d) TEM-EDS image of Fe2(CoNi)Te material. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1

[0025] (1) Preparation of Fe2(CoNi)-MOF materials

[0026] Ferric nitrate nonahydrate is Fe(NO3)3·9H2O, cobalt nitrate hexahydrate is Co(NO3)2·6H2O, nickel nitrate hexahydrate is Ni(NO3)2·6H2O, and N,N-dimethylformamide solution is DMF solution.

[0027] Fe(NO3)3.9H2O (2.5 mmol), Co(NO3)2.6H2O (1.25 mmol), Ni(NO3)2.6H2O (1.25 mmol) and 40 mmol of fumaric acid were dissolved in 50 ml of DMF solution, stirred at room temperature for 30 min at 200 rpm.

[0028] The above obtained solution was transferred to a reaction kettle, then placed in a 120°C oven for 8h, washed with deionized water and ethanol for several times after centrifugation at 3000 rpm for 3 min, and placed in a 40°C oven for drying for 8h to collect Fe2(CoNi)-MOF.

[0029] (2) Preparation of Fe2(CoNi)Te

[0030] Fe2(CoNi)MOF and tellurium powder were mixed uniformly at a mass ratio of 1:1, then calcined in a tube furnace at 500°C at a rate of 3°C / min in H2 / Ar atmosphere for 10h to obtain Fe2(CoNi)Te.

[0031] Example 2

[0032] Except that the ratio of Fe2(CoNi)MOF and tellurium powder in step (2) was changed to 1:0.8, the rest remained the same to obtain Fe2(CoNi)Te 0.8 .

[0033] Example 3

[0034] Except that the ratio of Fe2(CoNi)MOF and tellurium powder in step (2) was changed to 1:1.2, the rest remained the same to obtain Fe2(CoNi)Te 1.2 .

[0035] The morphology of Fe2(CoNi)-MOF material prepared in Example 1 was analyzed, as shown in Figure 1 The XRD results as shown in Figure 2 The TEM image as shown in (a) can be seen that Fe2(CoNi)-MOF presents a shuttle-shaped morphology with an average diameter of about 250 nm. The above evidence proves that Fe2(CoNi)-MOF is successfully prepared.

[0036] The morphology of Fe2(CoNi)Te material prepared is as shown in Figure 2(b) Fe2(CoNi)Te exhibits a spindle-shaped morphology, composed of telluride nanocrystals with an average diameter of 250 nm. The HRTEM of Fe2(CoNi)Te material is as follows: Figure 2 As shown in (c), the blue lattice stripe spacing is 0.264 nm, corresponding to the (002) crystal plane of NiTe2; the yellow lattice stripe spacing is 0.315 nm, corresponding to the (101) crystal plane of CoTe2; and the yellow lattice stripe spacing is 0.281 nm, corresponding to the (111) crystal plane of FeTe2. The TEM-EDS of Fe2(CoNi)Te material is as follows... Figure 2 (d) shows the uniform distribution of Fe, Co, Ni, and Te elements in Fe2(CoNi)Te. The Fe2(CoNi)Te prepared in Examples 1 to 3... x (Where x represents 0.8, 1, and 1.2 respectively) The X-ray diffraction patterns of the materials are as follows: Figure 3 As shown. Fe2(CoNi)Te x It exhibits typical diffraction peaks that correspond to standard cards for CoTe2 (PDF#89-2091), FeTe2 (PDF#14-0419), and NiTe2 (PDF#08-0004), which fully demonstrates the successful preparation of Fe2(CoNi)Te material.

[0037] Fe2(CoNi)Te 、 Fe2(CoNi)Te 0.8 and Fe2(CoNi)Te 1.2 Fe2(CoNi)Te@NF was prepared by loading it onto nickel foam (NF). 、 Fe2(CoNi)Te 0.8 @NF and Fe2(CoNi)Te 1.2 @NF three catalysts were subjected to electrochemical tests, and the results showed that at 10 mA / cm -2 and 100mAcm -2 At current densities, Fe2(CoNi)Te@NF exhibits a lower threshold potential than the catalyst Pt / C / RuO2, specifically at 10 mA cm⁻¹. -2 At the specified current density, after a 30-hour cycle stability test, Fe2(CoNi)Te@NF maintained 88.23% of its original performance. Therefore, Fe2(CoNi)Te@NF exhibits excellent water-splitting performance and demonstrates excellent cycle stability.

[0038] The embodiment only illustrates the patent and does not limit the protection scope of the patent, and the person skilled in the art can also make partial changes, as long as the changes do not exceed the spirit and essence of the patent, and are considered as equivalent replacement of the patent, and are within the protection scope of the patent.

Claims

1. A method for preparing a medium entropy metal chalcogenide, characterized in that, Comprising the following steps: S1 Dissolve ferric nitrate nonahydrate, cobalt nitrate hexahydrate, nickel nitrate hexahydrate and fumaric acid in N,N-dimethylformamide in a certain proportion, and stir uniformly; S2 Transfer the solution obtained above to a reaction kettle, place it in an oven for a period of time, centrifuge the reaction product, wash and dry at 40℃ for 8h to obtain Fe2(CoNi)-MOF; S3 calcining the obtained Fe2(CoNi)-MOF and tellurium powder in a H2 / Ar mixed gas at a certain ratio for a certain time to obtain a final Fe2(CoNi)Te x ; Wherein, the X is 0.8-1.

2.

2. The method for preparing a medium-entropy metal telluride according to claim 1, characterized in that, The molar mass ratio of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, nickel nitrate hexahydrate and fumaric acid in the step S1 is 2:1:1:

32.

3. The method for preparing a medium-entropy metal telluride according to claim 1, characterized in that, The stirring process in the step S1 is: stirring at room temperature for 30min, and the stirring speed is 200rpm.

4. The method of claim 1, wherein the medium-entropy metal chalcogenide is prepared by the steps of: providing a metal chalcogenide precursor; and annealing the metal chalcogenide precursor in a reducing atmosphere. The solution reaction temperature in the step S2 is 100-120℃, and the reaction time is 8-10h.

5. The application of the meso-entropy metal chalcogenide prepared by the preparation method of any one of claims 1-4 in the preparation of an electrolytic water hydrogen production catalyst.

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