A P-CoPt3 / P-CoMoO4 heterostructure hydrogen evolution electrocatalyst, a preparation method and application thereof

Abstract

The application belongs to the technical field of catalysts, and particularly discloses a P-CoPt3 / P-CoMoO4 heterostructure hydrogen evolution electrocatalyst, a preparation method and application thereof. The hydrogen evolution electrocatalyst comprises a foam nickel substrate and a catalytically active material loaded on the surface of the foam nickel substrate, wherein the catalytically active material comprises phosphorus-doped CoMoO4 and phosphorus-doped CoPt3; the phosphorus-doped CoMoO4 has a three-dimensional open nanorod array structure; the phosphorus-doped CoPt3 is anchored on the nanorod array; and the phosphorus-doped CoMoO4 and the phosphorus-doped CoPt3 form a heterostructure. The P-CoPt3 / P-CoMoO4 heterostructure hydrogen evolution electrocatalyst is generated by in-situ spontaneous oxidation-reduction reaction on the nanorod array by using a simple controllable solution immersion method, and the prepared hydrogen evolution heterostructure electrocatalyst has the characteristics of response sensitivity, high activity and long-term stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalysts, and particularly relates to a P-CoPt3 / P-CoMoO4 heterostructure hydrogen evolution electrocatalyst and a preparation method and application thereof. BACKGROUND

[0002] Hydrogen energy has the advantages of being clean, non-polluting, and having a wide access, and is considered as an ideal energy carrier. Hydrogen gas, as a sustainable, environmentally friendly, and high-energy-density energy carrier, has attracted widespread attention. Compared with traditional fossil energy hydrogen production, electrocatalytic water splitting for hydrogen production has greater advantages. Developing excellent electrocatalytic hydrogen evolution (HER) catalysts plays a crucial role in the development and utilization of renewable energy.

[0003] In an alkaline environment, the activity of hydrogen evolution reaction (HER) is usually low because of the high energy barrier of water dissociation in the Volmer step. Therefore, developing a HER catalyst with high activity under alkaline conditions to efficiently produce hydrogen has become an important research topic. According to the classical volcano plot theory, noble metals such as platinum and its derivative materials have ideal hydrogen adsorption / desorption Gibbs free energy, but due to the scarcity and high price of platinum resources, the cost of water electrolysis for hydrogen production is high, which limits the widespread application of hydrogen energy. Therefore, alloying is often used to reduce the content of noble metal platinum and improve its activity and stability, however, Pt-M (M = Co, Ni, Fe, and other transition metals) binary alloys show high activity for HER by adjusting the local coordination environment of Pt. However, the instability of Pt-M alloy due to the dissolution of M limits its further practical application. Heteroatom dopants (P, S) can alleviate the problem of M dissolution to some extent, but unfortunately, the HER catalytic activity of the obtained doped Pt-M alloy is not ideal. Therefore, improving the catalytic efficiency and stability of Pt-M alloy has attracted much attention.

[0004] At the same time, the current density of industrial application is usually 500 mA cm -2above, which will lead to the transition dissolution and shedding of the catalyst. Heterojunction engineering is widely considered as a promising method to improve the catalytic activity, in which the heterojunction adjusts the fine structure of the catalyst, and new and more active catalytic sites are generated on the heterojunction, thereby greatly improving the catalytic activity. Therefore, how to reduce the content of noble metal platinum and improve the stability of platinum-based alloy catalyst is currently an effective strategy to combine it with a self-supporting carrier to form a heterostructure, thereby improving the intrinsic activity and inherent stability of the catalyst, especially under industrial-level current density conditions. The existing modification methods to realize the heterostructure usually include electrodeposition, hydrothermal and atomic layer deposition, etc. However, these methods all need to consume additional energy, and there are problems such as complex process flow and low efficiency. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a P-CoPt3 / P-CoMoO4 heterostructure hydrogen evolution electrocatalyst and a preparation method and application thereof. The hydrogen evolution electrocatalyst has extremely low overpotential and good stability, and the preparation process is simple and efficient, and can be applied to industrial-level high current density water electrolysis hydrogen evolution.

[0006] The inventive concept of the present application is that the P-CoPt3 / P-CoMoO4 heterostructure hydrogen evolution electrocatalyst is generated by in-situ spontaneous redox reaction on the P-CoMoO4 nanorod array by using a simple and controllable solution immersion method. The hydrogen evolution electrocatalyst first synthesizes a CoMoO4 nanorod array by using a hydrothermal method, and then obtains a self-supported phosphorus-doped CoMoO4 nanorod array (P-CoMoO4) by using a high-temperature phosphating process. The P-CoMoO4 nanorod structure is beneficial to the transmission of large current; then the P-CoMoO4 nanorod array is immersed in a solution containing platinum ions, and a spontaneous redox reaction occurs at room temperature to obtain phosphorus-doped CoPt3 (P-CoPt3), and the P-CoPt3 is anchored on the three-dimensional open nanorod array P-CoMoO4, which not only can avoid the transition aggregation of P-CoPt3 to affect the exposure and utilization rate of the catalytic active site, but also can effectively inhibit the dissolution of the transition metal cobalt in CoPt3 and can avoid the shedding of P-CoPt3 from the carrier under high current density, thereby greatly improving the activity and long-term stability of the catalyst. Therefore, the P-CoPt3 / P-CoMoO4 heterostructure nanorod array hydrogen evolution electrocatalyst prepared by the present application has intrinsic catalytic activity and long-term stability superior to most platinum-based materials under the premise of low Pt loading, and has good application prospect under industrial-level high current density.

[0007] To solve the above technical problems, the first aspect of the present application provides a hydrogen evolution electrocatalyst, comprising a foam nickel substrate and a catalytically active material loaded on the surface of the foam nickel substrate, wherein the catalytically active material comprises phosphorus-doped CoMoO4 and phosphorus-doped CoPt3, the phosphorus-doped CoMoO4 has a three-dimensional open nanorod array structure, the phosphorus-doped CoPt3 is anchored on the nanorod array, and the phosphorus-doped CoMoO4 and the phosphorus-doped CoPt3 form a heterostructure.

[0008] In some embodiments of the present application, in the hydrogen evolution electrocatalyst, the loading amount of the catalytically active material is 9-10 mg / cm2. 2 .

[0009] In some embodiments of the present application, in the catalytically active material, the content of Pt is 5-15 wt%, the content of Mo is 30-40 wt%, the content of Co is 15-25 wt%, and the content of P is 1-5 wt%. In the catalytically active material of the present application, the content of the noble metal Pt is low, which can greatly save the production cost.

[0010] In some embodiments of the present application, in the catalytically active material, the content of Pt is 7-13 wt%, the content of Mo is 33-36 wt%, the content of Co is 20-23 wt%, and the content of P is 2-3 wt%.

[0011] The second aspect of the present application provides a preparation method of the above hydrogen evolution electrocatalyst, comprising the following steps:

[0012] (1) immersing the foam nickel into a mixed solution containing molybdate and cobalt salt, performing hydrothermal reaction, washing and drying to obtain cobalt molybdate grown on the surface of the foam nickel;

[0013] (2) placing the foam nickel with the cobalt molybdate grown on the surface obtained in step (1) and a phosphorus source in the downstream and upstream of the airflow of a reaction furnace respectively, heating and performing phosphorization reaction to obtain phosphorus-doped cobalt molybdate nanometer array, denoted as P-CoMoO4;

[0014] (3) immersing the P-CoMoO4 into a solution containing platinum ions, performing redox reaction at room temperature to generate P-CoPt3 in situ on the surface of the P-CoMoO4, washing and drying to obtain the hydrogen evolution electrocatalyst, denoted as P-CoPt3 / P-CoMoO4.

[0015] In some embodiments of the present application, in step (1), the foam nickel further comprises a pretreatment step before being immersed into the mixed solution, and the process of the pretreatment is as follows: immersing the foam nickel into an acid solution with a concentration of 1-6 mol / L, first ultrasonic cleaning, then cleaning with anhydrous ethanol and deionized water, and finally vacuum drying.

[0016] In some embodiments of the present application, the acidic solution is a hydrochloric acid solution.

[0017] In some embodiments of the present application, the ultrasonic cleaning is performed for 10-60 min.

[0018] In some embodiments of the present application, the vacuum drying is performed at a temperature of 55-65 ℃ for 10-15 hours.

[0019] In some embodiments of the present application, in step (1), the cobalt salt is selected from at least one of cobalt chloride, cobalt nitrate, cobalt sulfate, cobalt oxalate, cobalt acetylacetonate, and hydrates of the above-mentioned substances; preferably, the cobalt salt is cobalt nitrate hexahydrate.

[0020] In some embodiments of the present application, in step (1), the molybdate salt is selected from at least one of ammonium molybdate, sodium molybdate, and hydrates of the above-mentioned substances; preferably, the molybdate salt is ammonium molybdate tetrahydrate.

[0021] In some embodiments of the present application, in step (1), in the mixed solution, the concentration of the molybdate salt is 0.01-0.8 mol / L, the concentration of the cobalt salt is 0.01-1 mol / L, and the solvent is water and ethanol in a volume ratio of (0.5-3):1.

[0022] In some embodiments of the present application, in step (1), the hydrothermal reaction is performed at a temperature of 100-220 ℃ for 4-24 hours.

[0023] In some embodiments of the present application, in step (2), the phosphorus source is selected from at least one of red phosphorus, sodium hypophosphite, dihydrogen phosphate, hypophosphorous acid, triphenylphosphine, and hydrates of the above-mentioned substances; preferably, the phosphorus source is sodium hypophosphite monohydrate, sodium hypophosphite, or hypophosphorous acid monohydrate.

[0024] In some embodiments of the present application, in step (2), the phosphating reaction is performed at a temperature of 250-450 ℃ for 1-5 hours, and the heating rate is 2-6 ℃ / min.

[0025] In some embodiments of the present application, in step (2), the gas flow is nitrogen or argon, and the flow rate of the gas flow is 20-100 cc / min.

[0026] In some embodiments of the present application, in step (3), the solution containing platinum ions is selected from a solution of at least one of sodium hexachloroplatinate, platinum tetrachloride, ammonium chloroplatinate, platinum dichloride, potassium chloroplatinate, potassium chloroplatous acid, and platinum sulfite.

[0027] In some embodiments of the present application, the concentration of the solution containing platinum ions in step (3) is 1-15 mg / mL.

[0028] In some embodiments of the present application, the time of the redox reaction in step (3) is 0.5-8 hours; preferably 3-5 hours.

[0029] In some embodiments of the present application, after the reduction reaction in step (3) is completed, the reaction product is subjected to deionized water cleaning and vacuum drying, the temperature of the vacuum drying is 50-80℃, and the time is 6-24 hours.

[0030] The third aspect of the present application provides the use of the above-mentioned hydrogen evolution electrocatalyst in the electrolysis of water to produce hydrogen.

[0031] In some embodiments of the present application, in the electrolysis of water to produce hydrogen, the electrolyte is a KOH solution, the hydrogen evolution electrocatalyst is a working electrode, Hg / HgO is a reference electrode, and a graphite rod is a counter electrode.

[0032] In some embodiments of the present application, the concentration of the KOH solution is 1 mol / L.

[0033] The above technical solutions of the present application have at least the following technical effects or advantages compared with the prior art:

[0034] (1) The active component of the hydrogen evolution electrocatalyst of the present application is phosphorus-doped cobalt molybdate (P-CoMoO4) with a three-dimensional open nanorod array structure and phosphorus-doped CoPt3 (P-CoPt3), and P-CoPt3 is anchored on the nanorod array of P-CoMoO4 and forms a stable heterostructure. Among them: the P-CoMoO4 nanorod structure is beneficial to the transmission of large current, P-CoPt3 is anchored on the nanorod array to avoid the transition aggregation of P-CoPt3, thereby affecting the exposure and utilization rate of the catalytic active site, and the strong interaction between P-CoPt3 and the P-CoMoO4 carrier can effectively inhibit the dissolution of the transition metal cobalt in the catalyst, and can avoid the shedding of P-CoPt3 carrier under high current density, thereby significantly improving the catalyst activity and long-term stability.

[0035] (2) The P-CoPt3 / P-CoMoO4 heterostructure hydrogen evolution electrocatalyst is generated by a simple controllable solution soaking method in situ spontaneous redox reaction on the nanorod array. First, the cobalt molybdate nanorod array is grown on the surface of the nickel foam, and then the cobalt molybdate nanorod array is phosphated under inert gas protection to obtain the P-CoMoO4 nanorod array; the P-CoMoO4 nanorod array is soaked in a solution containing platinum ions, and the P-CoPt3 / P-CoMoO4 heterostructure nanorod array electrolytic water hydrogen evolution electrocatalyst is generated in situ by spontaneous redox reaction. The preparation method is simple, low in cost and friendly to the environment, and the prepared hydrogen heterostructure hydrogen evolution electrocatalyst has the characteristics of high porosity, large surface area, high active site density, low resistance and nanorod array structure. Therefore, in the electrolytic water hydrogen evolution reaction at low and high current densities, the hydrogen evolution heterostructure electrocatalyst prepared by the application shows the characteristics of sensitive response, high activity and long-term stability. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The XRD pattern of P-CoPt3 / P-CoMoO4 prepared in Example 1;

[0037] Figure 2 The SEM pattern of P-CoMoO4 prepared in Example 1;

[0038] Figure 3 The SEM pattern of P-CoPt3 / P-CoMoO4 prepared in Example 1;

[0039] Figure 4 The TEM pattern and Mapping pattern of P-CoPt3 / P-CoMoO4 prepared in Example 1;

[0040] Figure 5 The linear voltammetry scan pattern of the hydrogen evolution electrocatalyst of P-CoPt3 / P-CoMoO4 prepared in Example 1 and Comparative Examples 1-3 in 1 mol / L KOH electrolyte;

[0041] Figure 6 The linear voltammetry scan pattern of P-CoPt3 / P-CoMoO4 prepared in Example 1 in 1 mol / L KOH electrolyte at 500 mA cm -2 The chronoamperometric curve of the industrial current density in 1 mol / L KOH electrolyte;

[0042] Figure 7 The linear voltammetry scan pattern of P-CoPt3 / P-CoMoO4 prepared in Examples 1-3 in 1 mol / L KOH electrolyte;

[0043] Figure 8Linear voltammetry scan plots of P-CoPt3 / P-CoMoO4 prepared in Example 1 and Pt-CoNi-LDH prepared in Comparative Example 4 in 1 mol / L KOH electrolyte;

[0044] Figure 9 Mass activity curves of P-CoPt3 / P-CoMoO4 prepared in Example 1, Pt-CoNi-LDH prepared in Comparative Example 4 and 20 wt% Pt / C hydrogen evolution electrocatalyst of Comparative Example 3. DETAILED DESCRIPTION

[0045] The application will be described in greater detail below with reference to the embodiments. It should be particularly pointed out that the embodiments are only used to further illustrate the application and should not be understood as limiting the scope of protection of the application. Non-essential improvements and adjustments to the application made by those skilled in the art based on the above description should still fall within the scope of protection of the application. Meanwhile, the raw materials mentioned below that are not described in detail are all commercially available products; the process steps or preparation methods that are not mentioned in detail are all known to those skilled in the art.

[0046] Example 1

[0047] A preparation method of a hydrogen evolution electrocatalyst, comprising the following steps:

[0048] (1) A 1 mm thick foam nickel was cut into a square of 3 cm × 3 cm, and was placed in a 3 mol / L hydrochloric acid solution for ultrasonic cleaning for 30 min to remove the surface oxide layer. After the hydrochloric acid treatment, the foam nickel was immediately cleaned with deionized water and ethanol for 4 times, respectively, to obtain a pretreated foam nickel;

[0049] (2) 346 mg of ammonium molybdate tetrahydrate with a purity of 99.9% and 325 mg of cobalt nitrate hexahydrate with a purity of 99.9% were weighed and dissolved in a mixed solution of 10 mL of deionized water and 20 mL of ethanol to obtain a uniform solution after stirring for 15 min. Then the pretreated foam nickel obtained in step (1) was added to the mixed solution, and the reaction was carried out at a temperature of 180°C for 6 hours to obtain a CoMoO4·xH2O precursor nanorod array catalyst grown on the surface of the foam nickel;

[0050] (3) The CoMoO4·xH2O precursor prepared in step (2) and 2 g of sodium hypophosphite monohydrate were placed in the ceramic boat in the tube furnace, respectively, wherein: the sodium hypophosphite monohydrate was located upstream of the gas flow, and the CoMoO 4 ·The CoMoO4·xH2O precursor is located downstream of the gas flow; the tube furnace is heated to 350°C at a heating rate of 3°C / min, and maintained for 3 hours in an argon environment; after the reaction is completed, the temperature is cooled to room temperature, and phosphorus-doped cobalt molybdate is prepared, denoted as P-CoMoO4.

[0051] (4) The P-CoMoO4 prepared in step (3) is placed in a 20 mL chloroplatinic acid solution with a concentration of 2 mmol / L, and soaked at 25°C for 4 hours, and then taken out and washed with deionized water and ethanol for 3 times each; and then dried in a vacuum drying oven at 60°C for 12 hours, to prepare a heterostructure hydrogen evolution electrocatalyst composed of phosphorus-doped CoPt3 and phosphorus-doped CoMoO4, denoted as P-CoPt3 / P-CoMoO4-4h.

[0052] Example 2

[0053] A preparation method of a hydrogen evolution electrocatalyst, comprising the following steps:

[0054] (1) A 1 mm thick foam nickel is cut into a square of 4 cm × 3 cm, and placed in a hydrochloric acid solution with a concentration of 5 mol / L, and ultrasonically cleaned for 30 min to remove the surface oxide layer; after the hydrochloric acid treatment, the foam nickel is immediately washed with deionized water and ethanol for 5 times each, to prepare a pretreated foam nickel;

[0055] (2) 415 mg of ammonium molybdate with a purity of 99.9% tetrahydrate and 397 mg of cobalt nitrate with a purity of 99.9% hexahydrate are weighed and dissolved in a mixed solution of 10 mL of deionized water and 20 mL of ethanol to obtain a uniform solution; then the pretreated foam nickel in step (1) is added to the mixed solution, and reacted at a temperature of 150°C for 8 hours, to prepare a cobalt molybdate grown on the surface of the foam nickel, i.e. a CoMoO4·xH2O precursor nanorod array catalyst;

[0056] (3) The CoMoO4·xH2O precursor prepared in step (2) and 2 g of 8 times sodium phosphate are respectively placed in the ceramic boat in the tube furnace, wherein: monosodium hypophosphite is located upstream of the gas flow, and the CoMoO4·xH2O precursor is located downstream of the gas flow; the tube furnace is heated to 450°C at a heating rate of 5°C / min, and maintained for 2.5 hours in an argon environment; after the reaction is completed, the temperature is cooled to room temperature, and phosphorus-doped cobalt molybdate is prepared, denoted as P-CoMoO4.

[0057] (4) The P-CoMoO4 prepared in step (3) is placed in 20 mL of a chloroplatinic acid solution with a concentration of 5 mmol / L, soaked at 25°C for 3 hours, and then taken out and washed with deionized water and ethanol for 3 times respectively; and then dried in a vacuum drying oven at 70°C for 10 hours to prepare a heterostructure hydrogen evolution electrocatalyst composed of phosphorus-doped CoPt3 and phosphorus-doped CoMoO4, which is recorded as P-CoPt3 / P-CoMoO4-3h.

[0058] Example 3

[0059] A preparation method of a hydrogen evolution electrocatalyst, comprising the following steps:

[0060] (1) A 1mm-thick foamed nickel is cut into a square with a size of 2.5 cm × 4.5 cm, and then placed in hydrochloric acid with a concentration of 4 mol / L for ultrasonic cleaning for 60 min to remove the oxide layer on the surface of the foamed nickel; immediately after the hydrochloric acid treatment, the foamed nickel is washed with deionized water and ethanol for 3 times respectively to prepare a pretreated foamed nickel;

[0061] (2) 578 mg of ammonium molybdate tetrahydrate with a purity of 99.9% and 552 mg of cobalt nitrate hexahydrate with a purity of 99.9% are weighed and dissolved in a mixed solution composed of 10 mL of deionized water and 20 mL of ethanol to obtain a uniform solution after stirring for 15 min; then the pretreated foamed nickel prepared in step (1) is added into the mixed solution, and a cobalt molybdate xH2O precursor nanorod array catalyst grown on the surface of the foamed nickel is prepared under the condition of a temperature of 120°C for 16 hours;

[0062] (3) The CoMoO4·xH2O precursor prepared in step (2) and 2 g of sodium hypophosphite monohydrate are respectively placed in the ceramic boat in the tube furnace, wherein: the sodium hypophosphite monohydrate is located upstream of the gas flow, and the CoMoO4·xH2O precursor is located downstream of the gas flow; the tube furnace is heated to 350°C at a heating rate of 3°C / min, and kept for 3 hours under an argon environment; after the reaction is completed, the temperature is cooled to room temperature to prepare phosphorus-doped cobalt molybdate, which is recorded as P-CoMoO4.

[0063] (4) The P-CoMoO4 prepared in step (3) is placed in 20 mL of a chloroplatinic acid solution with a concentration of 3 mmol / L, soaked at 25°C for 5 hours, and then taken out and washed with deionized water and ethanol for 3 times respectively; and then dried in a vacuum drying oven at 50°C for 12 hours to prepare a heterostructure hydrogen evolution electrocatalyst composed of phosphorus-doped CoPt3 and phosphorus-doped CoMoO4, which is recorded as P-CoPt3 / P-CoMoO4-5h.

[0064] Comparative Example 1

[0065] P-CoMoO4 prepared in step (3) of Example 1 was used as the hydrogen evolution electrocatalyst of Comparative Example 1.

[0066] Comparative Example 2

[0067] P-CoPt3 was used as the hydrogen evolution electrocatalyst of Comparative Example 2, and the preparation steps thereof were as follows:

[0068] (1) 1.2 mL of chloroplatinic acid solution (0.4 mol / L) and 24 mg of Co(acac)2 were added to 12 mL of ethylene glycol (EG) to obtain a precursor solution; then 600 mg of KOH and 8 mL of DMF were added to the precursor solution and continuously stirred for about 2 hours, and then the obtained uniform solution was transferred to a reaction kettle and reacted at 160°C for 12 hours;

[0069] (2) The powder product was collected by centrifugation, then washed with a mixed solution of deionized water and ethanol, and finally dried in a vacuum oven at 70°C overnight to obtain CoPt3 powder;

[0070] (3) Sodium hypophosphite monohydrate and CoPt3 powder prepared in step (2) (mass ratio of 1:10) were respectively placed in ceramic boats in a tube furnace, wherein: sodium hypophosphite monohydrate was located upstream of the gas flow, and CoPt3 powder was located downstream of the gas flow; heat treatment was carried out at 300°C for 2 hours under the protection of nitrogen atmosphere, and then cooled to room temperature to obtain a phosphorus-doped CoPt3 hydrogen evolution electrocatalyst, which was denoted as P-CoPt3.

[0071] Comparative Example 3

[0072] A commercially available platinum carbon catalyst Pt / C (Aldrich, Pt loading of 20 wt%) was used as the hydrogen evolution electrocatalyst of Comparative Example 3.

[0073] Comparative Example 4

[0074] Referring to Example 1 of Chinese Invention Patent (Publication No.: CN 118360626 A), a Pt-NiCo-LDH hydrogen evolution electrocatalyst was prepared by electrodeposition method, including the following steps:

[0075] (1) 0.2908 g of Ni(NO3)2·6H2O and 0.582 g of Co(NO3)2·6H2O were weighed and dissolved in 100 mL of deionized water, and stirred at room temperature for 5 min;

[0076] (2) The foamed nickel (size of 1 cm x 2 cm) was treated with 3 mol / L hydrochloric acid for 10-12 min, then cleaned, soaked with deionized water, and ultrasonicated for 5-7 min, and the operation of replacing deionized water and ultrasonication was repeated for 3-5 times, and then dried with a hair dryer;

[0077] (3) Pour 80 mL of the solution in step (1) into a 100 mL electrolytic cell, use the foamed nickel in step (2) as the working electrode, Pt sheet as the counter electrode, and silver / silver chloride electrode as the reference electrode, and connect according to the three-electrode system;

[0078] (4) Deposit for 900 seconds under the condition of constant voltage electrochemical deposition method at -1V, repeatedly rinse with deionized water, and dry in a 60℃ vacuum oven for 3 hours;

[0079] (5) Weigh 0.0328 g of H2PtCl6 and 11.2212 g of KOH, and dissolve them in 200 mL of deionized water, and stir for 20 min at room temperature;

[0080] (6) Pour 80 mL of the solution in step (5) into a 100 mL electrolytic cell, use the sample obtained in step (4) as the working electrode, carbon rod as the counter electrode, and mercury / mercury oxide electrode as the reference electrode, and connect according to the three-electrode system;

[0081] (7) Deposit for 5000 seconds under the condition of linear sweep voltammetry at a scan rate of 5 mV / s, repeatedly rinse with deionized water, and dry in a 60℃ vacuum oven for 3 hours to prepare the Pt-NiCo-LDH hydrogen evolution electrocatalyst.

[0082] Performance test

[0083] 1. Component analysis and microstructure

[0084] Figure 1 The XRD pattern of the hydrogen evolution electrocatalyst prepared in Example 1 is as follows: Figure 1 The abscissa 2θ in the above figure represents the diffraction angle, and the ordinate Intensity represents the intensity of the diffraction peak. It can be seen from the above figure that: Figure 1 CoMoO4 without phosphating treatment and P-CoMoO4 after phosphating treatment are both pure single phase, corresponding to the standard card PDF # -21-0868 of CoMoO4, and P-CoMoO4 prepared in Example 1 will undergo spontaneous redox reaction after being treated by soaking in the solution containing platinum ions, and P-CoPt3 new phase is generated, which corresponds to the standard derivation peak PDF # -29-0499 of CoPt3.

[0085] Figure 2 and Figure 3 are the SEM images of P-CoMoO4 and P-CoPt3 / P-CoMoO4 prepared in Example 1, respectively. Figure 2The micro-morphology diagram of P-CoMoO4 obtained by phosphating the nanorod array in-situ and uniformly grown on the nickel foam, and the self-supporting three-dimensional open nanorod array structure is beneficial to the exchange of reactive substances and the rapid escape of bubbles, especially a large amount of H2 bubbles will be rapidly formed under high current density. Figure 3 The P-CoPt3 / P-CoMoO4 heterostructure nanometer array morphology diagram is for anchoring P-CoPt3 on the P-CoMoO4 nanorod, the nanorod P-CoMoO4 has super hydrophilicity, and the nanorod structure is beneficial to the rapid transmission of electrons, and P-CoPt3 is anchored on the nanorod P-CoMoO4 carrier as the main active site, which is beneficial to improve the utilization rate of the reaction active site, and provides a new scheme for solving the rapid release of bubbles and the shedding and loss of powdery catalyst under industrial current density.

[0086] Figure 4 The TEM diagram of the P-CoPt3 / P-CoMoO4 heterostructure prepared in Example 1, the HR-TEM (High Resolution Transmission Electron Microscopy) analysis of the P-CoPt3 / P-CoMoO4 heterostructure confirms the existence of the hetero-interface structure of P-CoPt3 and P-CoMoO4. Figure 4 a and Figure 4 b) and the lattice fringes (c) analysis confirms the existence of the hetero-interface structure of P-CoPt3 and P-CoMoO4; the line scan (d) and (e) and the Mapping diagram (f) and (g) also confirm that P is successfully doped in CoPt3, which all indicates that the P-CoPt3 nanoparticles are in-situ generated by immersing P-CoMoO4 in the solution containing platinum ions, and are anchored on P-CoMoO4 to form a high-activity and stable heterostructure catalyst. Figure 4 Figure 4 d and Figure 4 e) and the Mapping diagram (f) and (g) also confirm that P is successfully doped in CoPt3, which all indicates that the P-CoPt3 nanoparticles are in-situ generated by immersing P-CoMoO4 in the solution containing platinum ions, and are anchored on P-CoMoO4 to form a high-activity and stable heterostructure catalyst. Figure 4 The content of the hydrogen evolution electrocatalyst elements in Examples 1-3 and Comparative Examples 1-2 and 4 is tested by ICP-OES, and the results are shown in Table 1.

[0087] Table 1:

[0088]

[0089] From Table 1, it can be seen that the content of the noble metal Pt in the hydrogen evolution electrocatalyst prepared in Examples 1-3 is low, which is 7.9-12.1wt%, lower than the Pt content in the platinum carbon catalyst 20wt% Pt / C of Comparative Example 3 and the Pt content in the P-CoPt3 catalyst of Comparative Example 2.

[0090] 2. Electrochemical performance

[0091]

[0092] ​​In a 1 mol / mL KOH electrolyte, the hydrogen evolution electrocatalysts of Examples 1-3 and Comparative Examples 1-4 were used as working electrodes, Hg / HgO as reference electrodes, and graphite rods as counter electrodes to test their electrochemical performance.

[0093] The specific experimental procedure is as follows:

[0094] A 1 mol / mL KOH electrolyte was prepared, and nitrogen gas was introduced at a rate of 20 mL / min for 20 min to saturate the solution with nitrogen. Then, the hydrogen evolution electrocatalysts of Examples 1-3 and Comparative Examples 1-4 were used as working electrodes, Hg / HgO as reference electrodes, and graphite rods as counter electrodes, respectively, connected to an electrochemical workstation. Linear voltammetry was then performed on the electrode material at a scan rate of 5 mV / s. The results are as follows: Figure 5 and Figures 7-9 At 500 mA cm -2 Its stability was tested under industrial-grade current density using time-potential (ET) measurements, and the results are as follows: Figure 6 As shown.

[0095] Figure 5 Linear voltammetric scans of the P-CoPt3 / P-CoMoO4 prepared in Example 1 and the hydrogen evolution electrocatalysts of Comparative Examples 1-3 are shown. Figure 5 The horizontal axis represents voltage, and the vertical axis represents current density. From... Figure 5 It can be seen that the P-CoPt3 / P-CoMoO4 heterostructure nanorod array hydrogen evolution electrocatalyst prepared in Example 1 has better hydrogen evolution performance than P-CoPt3, P-CoMoO4 and commercial Pt / C, with a performance of 10 mA cm⁻¹. -2 and 1000 mA cm -2 The overpotentials at the current densities were 23 mV and 145 mV, respectively, and the electrocatalytic activity was significantly better than that of P-CoPt3 (28 mV, 367 mV), P-CoMoO4 (71 mV, 420 mV) and Pt / C (36 mV, 647 mV). This may be because P-CoPt3 is anchored on the three-dimensional open nanorod array of P-CoMoO4, which is conducive to the full exposure of catalytic active sites. In addition, the strong interaction between metal P-CoPt3 and the support P-CoMoO4 is also conducive to enhancing the electrocatalytic activity of the heterostructure catalyst.

[0096] Figure 6 The chronocurrent curves of P-CoPt3 / P-CoMoO4 prepared in Example 1 are shown. Figure 6 The horizontal axis, Time, represents time, and the vertical axis, Potential, represents voltage. Figure 6 It can be seen that at 500 mA cm-2 Under the industrial current density conditions, the P-CoPt3 / P-CoMoO4 hydrogen evolution electrocatalyst can be stably operated for more than 300 hours without attenuation, which indicates that the P-CoPt3 / P-CoMoO4 heterostructure nanorod array hydrogen evolution electrocatalyst has excellent long-term stability, which is due to the superhydrophilic property of the nanorod P-CoMoO4, which is beneficial to the rapid release of H2 generated by the reaction; at the same time, the strong interaction between the metal P-CoPt3 and the carrier P-CoMoO4 synergistically enhances its stability.

[0097] Figure 7 The linear voltammetry scan graph of the P-CoPt3 / P-CoMoO4 prepared for Examples 1-3 in 1 mol / L KOH electrolyte is shown in Figure 1. Figure 7 From Figure 1 and Table 1, it can be determined that the optimal P-CoMoO4 suitable for the present application is the immersion time in the solution containing platinum ions and the Pt loading, and when the immersion time is 4 hours, it has good catalytic activity, and it has a 10- and 1000-mA cm -2 The overpotential under the current density is 23 mV and 145 mV, which is better than that of the immersion for 3 hours (29 mV, 215 mV) and the immersion for 5 hours (27 mV, 182 mV); and when the Pt content in the P-CoPt3 / P-CoMoO4 is 9.7wt%, it has the optimal hydrogen evolution catalytic activity.

[0098] Figure 8 The linear voltammetry scan graphs of the P-CoPt3 / P-CoMoO4 prepared for Example 1 and the Pt-CoNi-LDH prepared for Comparative Example 4 are shown in Figure 2. Figure 8 It can be found that the P-CoPt3 / P-CoMoO4 has an extremely low overpotential and excellent hydrogen evolution performance, and the electrocatalytic hydrogen evolution performance is significantly better than that of the Pt-CoNi-LDH, and it has a 10- and 300-mA cm -2 and 142 mV under the current density, which is significantly better than the 26 mV and 174 mV of the Pt-CoNi-LDH. -2

[0099] Figure 9 The mass activity curves of the P-CoPt3 / P-CoMoO4 prepared for Example 1, the Pt-CoNi-LDH prepared for Comparative Example 4, and the 20wt% Pt / C catalyst of Comparative Example 3 are shown in Figure 3. Figure 9 It can be found from Figure 3 that the P-CoPt3 / P-CoMoO4 has excellent mass activity, which is significantly higher than that of the Pt-CoNi-LDH and the commercial Pt / C.

[0100] ​For those skilled in the art of the present application, without departing from the concept of the present application, can make several simple deductions or substitutions, without having to go through the creative labor. Therefore, the simple improvements made by the person skilled in the art according to the disclosure of the present application, should be within the scope of protection of the present application. The above examples are the preferred embodiments of the present application, any similar process and equivalent changes made, should belong to the protection scope of the present application.

Claims

1. A hydrogen evolution electrocatalyst, characterized in that, The invention includes a nickel foam substrate and a catalytically active material supported on the surface of the nickel foam substrate. The catalytically active material includes phosphorus-doped CoMoO4 and phosphorus-doped CoPt3. The phosphorus-doped CoMoO4 has a three-dimensional open nanorod array structure, and the phosphorus-doped CoPt3 is anchored on the nanorod array. The phosphorus-doped CoMoO4 and phosphorus-doped CoPt3 form a heterostructure.

2. The hydrogen evolution electrocatalyst according to claim 1, characterized in that, In the hydrogen evolution electrocatalyst, the loading of the catalytically active material is 9-10 mg / cm³. 2 .

3. The hydrogen evolution electrocatalyst according to claim 1, characterized in that, In the catalytically active material, the content of Pt is 5-15 wt%, the content of Mo is 30-40 wt%, the content of Co is 15-25 wt%, and the content of P is 1-5 wt%.

4. A method for preparing a hydrogen evolution electrocatalyst as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) The nickel foam was immersed in a mixed solution containing molybdate and cobalt salt for hydrothermal reaction. After washing and drying, cobalt molybdate was grown on the surface of the nickel foam. (2) The nickel foam with cobalt molybdate grown on the surface obtained in step (1) and the phosphorus source are placed downstream and upstream of the gas flow in the reactor, respectively, and heated to carry out phosphating reaction to obtain phosphorus-doped cobalt molybdate nanoarray, denoted as P-CoMoO4. (3) The P-CoMoO4 is immersed in a solution containing platinum ions and a redox reaction is carried out at room temperature to generate P-CoPt3 in situ on the surface of P-CoMoO4. After washing and drying, the hydrogen evolution electrocatalyst is obtained and is denoted as P-CoPt3 / P-CoMoO4.

5. The method for preparing the hydrogen evolution electrocatalyst according to claim 4, characterized in that, In step (1), the nickel foam is further subjected to a pretreatment step before being immersed in the mixed solution. The pretreatment process is as follows: the nickel foam is immersed in an acidic solution of 1-6 mol / L, first ultrasonically cleaned, then cleaned with anhydrous ethanol and deionized water, and then vacuum dried.

6. The method for preparing the hydrogen evolution electrocatalyst according to claim 4, characterized in that, In step (1), the cobalt salt is selected from at least one of cobalt chloride, cobalt nitrate, cobalt sulfate, cobalt oxalate, cobalt acetylacetonate, and hydrates of the above substances; And / or, the molybdate is selected from at least one of ammonium molybdate, sodium molybdate, and hydrates of the above substances; And / or, in the mixed solution, the concentration of molybdate is 0.01-0.8 mol / L, the concentration of cobalt salt is 0.01-1 mol / L, and the solvent is water and ethanol in a volume ratio of (0.5-3):1; And / or, the temperature of the hydrothermal reaction is 100-220 °C, and the time of the hydrothermal reaction is 4-24 hours.

7. The method for preparing the hydrogen evolution electrocatalyst according to claim 4, characterized in that, In step (2), the phosphorus source is selected from at least one of red phosphorus, sodium hypophosphite, dihydrogen phosphate, hypophosphite, triphenylphosphine, and hydrates of the above substances; And / or, the temperature of the phosphating reaction is 250-450 °C, and the time of the phosphating reaction is 1-5 hours; And / or, the gas flow is nitrogen or argon, and the gas flow rate is 20-100 cc / min.

8. The method for preparing the hydrogen evolution electrocatalyst according to claim 4, characterized in that, In step (3), the platinum ion-containing solution is selected from at least one of sodium chloroplatinate hexagenate, platinum tetrachloride, ammonium chloroplatinate, platinum dichloride, potassium chloroplatinate, potassium chloroplatinate, and platinum sulfite. And / or, the concentration of the platinum ion-containing solution is 1-15 mg / mL.

9. The method for preparing the hydrogen evolution electrocatalyst according to claim 4, characterized in that, In step (3), the redox reaction takes 0.5-8 hours.

10. The application of the hydrogen evolution electrocatalyst according to any one of claims 1-3 in the electrolysis of water to produce hydrogen.

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