Medium-entropy metal telluride and preparation method and application thereof

Abstract

The invention discloses medium-entropy metal telluride and a preparation method and application thereof.The preparation method comprises the specific steps that metal salt and fumaric acid are in an N, N-dimethylformamide solvent environment, metal ions and carboxyl are made to make full contact and coordinate, and a metal-organic complex precursor solution is constructed; reacting the precursor solution at a specific temperature to form an ordered crystal structure, namely Fe2 (CoNi)-MOF, in molecules and among the molecules of the metal-organic complex through a complex chemical rearrangement and bonding process; fe2 (CoNi)-MOF and tellurium powder are subjected to a series of synergistic reactions under high-temperature calcination of H2 / Ar mixed gas, and the medium-entropy metal telluride is generated. The medium-entropy metal telluride prepared by the invention has efficient catalytic hydrogen evolution and oxygen evolution potential in a water electrolysis hydrogen production reaction, can greatly improve catalytic efficiency and reaction dynamic characteristics, and is used for preparing a water electrolysis hydrogen production catalyst.

Description

Technical Field

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

[0002] Catalysts used for hydrogen production reactions are generally precious metal catalysts. Although precious metal catalysts have excellent performance, they are costly, have limited resources and poor stability, which limits their large-scale application. Therefore, finding efficient, stable and low-cost catalyst materials has always been the focus of research in the field of catalyst technology for hydrogen production by electrolysis of water. Metal-organic framework (MOF) materials have received extensive attention in the field of catalyst preparation due to their unique structural properties, such as good coordination environment, structural flexibility and composition adjustability. However, traditional MOF materials still have problems such as limited number of active sites, insufficient intrinsic conductivity and high reaction energy barrier in certain catalytic reactions, and cannot completely replace precious metal catalysts. Therefore, it is urgent to develop a new type of non-precious metal material with excellent catalytic activity and high stability for the preparation of catalyst materials. Summary of the invention

[0003] The purpose of the present invention is to develop a non-precious metal catalyst material with excellent overall water splitting performance and cycle stability for use in preparing a water-to-hydrogen catalyst.

[0004] The embodiments of the present application disclose a medium-entropy metal telluride, wherein the medium-entropy metal telluride is a multi-metal MOF constructed based on two or more medium-entropy metal ions and organic ligands, and the multi-metal MOF is reacted with tellurium powder through high-temperature calcination to form a material.

[0005] Preferably, the tellurium metal ions are specifically three kinds, namely Fe+, Co+ and Ni+.

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

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

[0008] S1: dissolving a certain amount of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, nickel nitrate hexahydrate and fumaric acid in N,N-dimethylformamide and stirring well;

[0009] S2: placing the above-obtained solution in an oven to react for a period of time, centrifuging the reaction product, washing it, and drying it at 40° C. for 8 h to obtain an iron-cobalt-nickel metal-organic framework (Fe2(CoNi)-MOF);

[0010] S3: The Fe2(CoNi)-MOF and tellurium powder obtained above are calcined in a H2 / Ar mixed gas at a certain ratio for a certain period of time at a high temperature to obtain the final iron-cobalt-nickel three-element metal-organic framework telluride derivative (Fe2(CoNi)Te x ).

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

[0012] Preferably, the stirring process in step S1 is: stirring at room temperature for 30 minutes at a stirring speed of 200 rpm.

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

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

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

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

[0017] The advantages of the present invention are that the magnetic iron, cobalt and nickel nanoparticles show high activity in the catalytic process of hydrogen evolution and oxygen evolution reactions. Compared with traditional alloys, they have higher configuration energy, excellent mechanical stability and corrosion resistance, which ensures the stability of the chemical composition of the catalyst prepared from these three metal elements in alkaline electrolyte. After the MOF precursor is converted into a medium-entropy metal telluride, the d-band center of the metal site is close to the Fermi level, which improves the adsorption / desorption problem of the electrocatalyst to *H and significantly reduces the rate-determining step of the Gibbs free energy. Tellurium powder is used as a tellurium source, and it is subjected to atomic diffusion and chemical bond recombination with pyrolytic metal active species to generate Fe2(CoNi)Tex, realizing the key transformation from MOF precursor to metal telluride, reshaping the electronic structure of the material, enriching the active sites, optimizing the catalytic performance, giving it the potential for efficient catalytic hydrogen evolution and oxygen evolution in the electrolysis of water to produce hydrogen, greatly improving the catalytic efficiency and reaction kinetics, and can be used to prepare hydrogen production catalyst materials, providing material support for solving the energy bottleneck of electrolysis of water to produce hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0020] Figure 2 Shown are TEM images of Fe2(CoNi)-MOF and Fe2(CoNi)Te materials prepared in Example 1.

[0021] Figure 3 The Fe2(CoNi)Te prepared in Example 1-3 is shown. x (where x=0.8, 1, 1.2).

[0022] In the figure: Figure 2 (a) is the TEM image of Fe2(CoNi)-MOF material; 2(b) is the TEM image of Fe2(CoNi)Te material; 2(c) is the HRTEM image of Fe2(CoNi)Te material; 2(d) is the TEM-EDS image of Fe2(CoNi)Te material. DETAILED DESCRIPTION

[0023] The following will describe the technical solutions in the embodiments of the present invention in detail in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1

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

[0026] Iron 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] Dissolve 2.5 mmol of Fe(NO3)3·9H2O, 1.25 mmol of Co(NO3)2·6H2O, 1.25 mmol of Ni(NO3)2·6H2O and 40 mmol of fumaric acid in 50 ml of DMF solution and stir at room temperature at 200 rpm for 30 min.

[0028] The solution obtained above was transferred to a reactor, and then placed in an oven at 120°C for reaction for 8 hours. After centrifugation at 3000 rpm for 3 minutes, it was washed with deionized water and ethanol for multiple times, and placed in an oven at 40°C for drying for 8 hours to obtain Fe2(CoNi)-MOF.

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

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

[0031] Example 2

[0032] Except for the change of the ratio of Fe2(CoNi)MOF to tellurium powder to 1:0.8 in step (2), the rest remain unchanged to obtain Fe2(CoNi)Te 0.8 .

[0033] Example 3

[0034] Except for the change of the ratio of Fe2(CoNi)MOF to tellurium powder to 1:1.2 in step (2), the rest remain unchanged to obtain Fe2(CoNi)Te 1.2 .

[0035] The morphology of the Fe2(CoNi)-MOF material prepared in Example 1 was analyzed. Figure 1 The XRD results shown show the typical diffraction peaks of Fe2(CoNi)-MOF. According to the indexed standard MIL-53 (CCDC No. 2088536) spectrum, the two diffraction peaks at 9.8° and 18.8° are in good agreement with the (200) and (201) crystal planes of standard MIL-53; Figure 2 The TEM image shown in a shows that Fe2(CoNi)-MOF has a spindle-shaped morphology with an average diameter of about 250nm. The above evidence proves that Fe2(CoNi)-MOF was successfully prepared.

[0036] The morphology of the prepared Fe2(CoNi)Te material is shown in Figure 2b, Fe2(CoNi)Te presents a spindle-shaped morphology, the interior is composed of telluride nanocrystals with an average diameter of 250nm. HRTEM of Fe2(CoNi)Te material Figure 2 As shown in Figure c, the spacing between the blue lattice fringes is 0.264nm, corresponding to the (002) crystal plane of NiTe2, the spacing between the yellow lattice fringes is 0.315nm, corresponding to the (101) crystal plane of CoTe2, and the spacing between the yellow lattice fringes is 0.281nm, corresponding to the (111) crystal plane of FeTe2. Figure 2 d, showing the uniform distribution of Fe, Co, Ni and Te elements in Fe2(CoNi)Te. x (where x is 0.8, 1, and 1.2 respectively) The X-ray diffraction pattern of the material is as follows Figure 3 Fe2(CoNi)Te x It shows typical diffraction peaks, which can correspond to CoTe2 (PDF#89-2091), FeTe2 (PDF#14-0419) and NiTe2 (PDF#08-0004) standard cards. The above evidence fully proves the successful preparation of Fe2(CoNi)Te material.

[0037] Fe2(CoNi)Te 、 Fe2(CoNi)Te 0.8 and Fe2(CoNi)Te 1.2 They were loaded on nickel foam (NF) to prepare Fe2(CoNi)Te@NF 、 Fe2(CoNi)Te 0.8 @NF and Fe2(CoNi)Te 1.2 @NF Three catalysts were electrochemically tested and the results showed that at 10mAcm -2 and 100mAcm -2 Fe2(CoNi)Te@NF has a lower threshold potential than Pt / C / RuO2 at current densities of 10 mA cm -2 Under the current density, after 30h of cycle stability test, the performance of Fe2(CoNi)Te@NF can still be maintained at 88.23% of the original. Therefore, Fe2(CoNi)Te@NF has excellent full water splitting performance and exhibits excellent cycle stability.

[0038] This implementation mode is only an exemplary description of this patent and does not limit its protection scope. Personnel in this field may also make partial changes to it. As long as it does not exceed the spirit of this patent, it shall be regarded as an equivalent replacement of this patent and shall be within the protection scope of this patent.

Claims

1. A medium-entropy metal telluride, characterized in that: The intermediate-entropy metal telluride is a multi-metal MOF constructed based on two or more intermediate-entropy metal ions and organic ligands, and the multi-metal MOF is reacted with tellurium powder through high-temperature calcination to form a material.

2. The medium-entropy metal telluride according to claim 1, characterized in that The tellurium metal ions are specifically three kinds, namely Fe+ 、 Co+ and Ni+.

3. The medium-entropy metal telluride according to claim 1, characterized in that The organic ligand is fumaric acid.

4. A method for preparing a medium-entropy metal telluride, characterized in that: The method for preparing medium-entropy metal telluride according to claim 3 comprises 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 well; S2: transferring the above obtained solution into a reactor, placing it in an oven to react for a period of time, centrifuging the reaction product, washing it, and drying it at 40°C for 8h to obtain Fe2(CoNi)-MOF; S3 The Fe2(CoNi)-MOF and tellurium powder obtained above are calcined in a H2 / Ar mixed gas at a certain ratio for a certain period of time to obtain the final Fe2(CoNi)Te x .

5. The preparation method according to claim 4, characterized in that: In the step S1, the molar mass ratio of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, nickel nitrate hexahydrate and fumaric acid is 2:1:1:

32.

6. The preparation method according to claim 4, characterized in that: The stirring process in step S1 is: stirring at room temperature for 30 minutes at a stirring speed of 200 rpm.

7. The preparation method according to claim 4, characterized in that: In step S2, the solution reaction temperature is 100-120° C., and the reaction time is 8-10 hours.

8. The preparation method according to claim 4, characterized in that: In step S3, the mass ratio of Fe2(CoNi)MOF to tellurium powder is 1:0.8~1.

2.

9. The medium-entropy metal telluride according to any one of claims 1 to 8, characterized in that: Used for the preparation of catalysts for hydrogen production by water electrolysis.

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