Electrolytic water cathode catalyst and method for preparing the same

Abstract

This invention belongs to the field of electrochemical technology, specifically relating to a water electrolysis cathode catalyst and its preparation method. The water electrolysis cathode catalyst of this invention comprises a SnO2 matrix, on which a first layer of noble metal Pt is loaded to obtain Pt / SnO2; MoS2 nanosheets are loaded on the surface of the Pt / SnO2 to obtain MoS2 / Pt / SnO2; a second layer of noble metal Pt is loaded on the surface of the MoS2 / Pt / SnO2 to obtain Pt / MoS2 / Pt / SnO2; wherein the loading amount of the first layer of noble metal Pt is 1-5% of the mass of the SnO2 matrix, the loading amount of the MoS2 nanosheets is 50-80% of the mass of Pt / SnO2, and the loading amount of the second layer of noble metal Pt is 1-10% of the mass of MoS2 / Pt / SnO2; the Pt / MoS2 / Pt / SnO2 catalyst serves as the water electrolysis cathode catalyst. This invention utilizes a combination of liquid-phase reduction, hydrothermal, and microwave methods to prepare a catalyst. The resulting catalyst exhibits excellent hydrogen evolution catalytic activity and a low cathode overpotential, reducing the amount of precious metals used and significantly lowering costs. It also demonstrates good catalytic performance during water electrolysis and hydrogen evolution, and has broad market prospects.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical technology, specifically relating to a cathode catalyst for water electrolysis and its preparation method. Background Technology

[0002] Hydrogen, as a novel energy source, boasts advantages such as environmental friendliness, high calorific value, and renewability, and is considered a clean energy carrier capable of replacing fossil fuels. Currently, industrial hydrogen production mainly relies on methane steam reforming and coal gasification processes, which not only depend on fossil fuels but also cause severe environmental pollution and emit large amounts of greenhouse gases. In contrast, water electrolysis for hydrogen production is considered an ideal method for large-scale hydrogen production due to its low cost, stable yield, and high purity.

[0003] In principle, the structure of a PEM water electrolysis device is similar to that of a PEM fuel cell, but they operate in different ways. In the operation of a PEM fuel cell, oxygen is reduced at the cathode and hydrogen is oxidized at the anode. In short, water is generated and an electric current is produced.

[0004] In PEM hydrolysis, the current and electrodes are reversed, and water decomposition occurs. Oxygen is released at the anode (OER—oxygen release reaction), while proton reduction (HER—hydrogen release reaction) occurs at the cathode, where protons migrate through the polymer electrolyte membrane. Thus, water is decomposed into hydrogen and oxygen by means of an electric current.

[0005] Currently, platinum black or Pt / C catalysts prepared by methods such as liquid-phase reduction and microwave reduction generally suffer from high preparation costs when used as cathode materials for water electrolysis. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a water electrolysis cathode catalyst and its preparation method. The catalyst of this invention is suitable for PEM water electrolysis cathode materials. It uses conductive oxide SnO2 as a matrix, loads a small amount of Pt, uniformly grows MoS2, and then deposits a certain amount of Pt to form a SnO2 / Pt / MoS2 / Pt composite material. Compared with general Pt / C catalysts, this catalyst reduces the amount of precious metals used, is carbon-free, is less prone to corrosion and shedding, and the use of conductive oxides as the matrix material further reduces the local overpotential of the water electrolysis cathode.

[0007] To achieve the above technical objectives, the technical solution adopted in the embodiments of the present invention is as follows:

[0008] In a first aspect, embodiments of the present invention provide a water electrolysis cathode catalyst, comprising a SnO2 matrix, wherein a first layer of noble metal Pt is loaded on the SnO2 matrix to obtain Pt / SnO2; MoS2 nanosheets are loaded on the surface of the Pt / SnO2 to obtain MoS2 / Pt / SnO2; a second layer of noble metal Pt is loaded on the surface of the MoS2 / Pt / SnO2 to obtain Pt / MoS2 / Pt / SnO2; wherein the loading amount of the first layer of noble metal Pt is 1-5% of the mass of the SnO2 matrix, the loading amount of the MoS2 nanosheets is 50-80% of the mass of Pt / SnO2, and the loading amount of the second layer of noble metal Pt is 1-10% of the mass of MoS2 / Pt / SnO2; the Pt / MoS2 / Pt / SnO2 catalyst serves as a water electrolysis cathode catalyst.

[0009] Secondly, embodiments of the present invention provide a method for preparing a cathode catalyst for water electrolysis, characterized by comprising the following steps:

[0010] SnO2 pretreatment

[0011] (1) Weighing of materials: Weigh 1-10g of SnO2 and add it to a 0.2-2M acid solution and stir for 2-12 hours to form a solution;

[0012] (2) Provide an etching environment: Place the solution from step (1) in a reaction vessel for hydrothermal treatment to obtain a solid sample;

[0013] (3) Removal of impurity ions: Wash the solid sample obtained in step (2) with deionized water until the washing solution is neutral;

[0014] (4) Catalyst drying: The solid sample cleaned in step (3) is placed in a tube furnace, calcined in an inert atmosphere and then cooled with the furnace to obtain roughened SnO2.

[0015] Pt / SnO2 loading

[0016] (5) Weighing of materials: Weigh platinum precursor and glucose, wherein the mass ratio of platinum precursor: SnO2: glucose = 0.003~0.01:1:0.01~0.1;

[0017] (6) Feeding: Prepare a 0.05-0.5M solution of the glucose weighed in step (5), then add SnO2 and platinum precursor, sonicate for 0.5-2 hours, and mix evenly;

[0018] (7) Adjust pH: Add 0.1-2M sodium hydroxide solution to the solution in step (6) until the solution is alkaline, while stirring continuously;

[0019] (8) Pt reduction: Add 10 mL of 0.05-1 M sodium borohydride solution to the solution in step (7) and stir for 0.5-6 h to reduce Pt to obtain a solid sample;

[0020] (9) Removal of impurity ions: Wash the solid sample from step (8) with deionized water to remove excess impurity ions;

[0021] (10) Catalyst drying: The solid sample washed in step (9) is placed in a vacuum drying oven and kept for 12-24 hours to obtain Pt / SnO2;

[0022] Preparation of MoS2-supported Pt / SnO2

[0023] (11) Weighing of materials: Weigh sodium molybdate and thioacetamide separately, wherein the mass ratio of sodium molybdate:thioacetamide:Pt / SnO2 is 1~3:1~4:1;

[0024] (12) Feeding: Dissolve the sodium molybdate and thioacetamide weighed in step (11) in 100-500 mL of deionized water and stir for 1-4 h to form a transparent solution. Then add the Pt / SnO2 from step (10) and continue stirring for 0.5-2 h.

[0025] (13) Growth of MoS2: The solution from step (12) was placed in a reaction vessel and reacted at 180-220°C for 12-24 hours. The mixture was then cooled with the furnace to obtain a solid sample.

[0026] (14) Removal of impurity ions: Wash the solid sample described in step (13) with deionized water to remove excess impurity ions;

[0027] (15) Catalyst drying: The solid sample cleaned in step (14) is placed in a vacuum drying oven and kept for 12-24 hours to obtain MoS2 / Pt / SnO2;

[0028] Preparation of Pt-supported MoS2 / Pt / SnO2

[0029] (16) Weighing of materials: Weigh the platinum precursor according to the mass ratio Pt:MoS2 / Pt / SnO2=1~100;

[0030] (17) Feeding: Place the MoS2 / Pt / SnO2 described in step (15) into an ethylene glycol solution and sonicate for 0.5 to 2 hours. Then add the platinum precursor weighed in step (16) and continue stirring for 2 to 12 hours.

[0031] (18) Pt microwave reduction: The solution from step (17) is microwave-heated for reduction treatment;

[0032] (19) Removal of impurity ions: Wash the solid sample obtained in step (18) with deionized water to remove excess impurity ions;

[0033] (20) Catalyst drying: The solid sample from step (19) is placed in a vacuum drying oven and heated for 12 to 24 hours to obtain the finished catalyst, denoted as Pt / MoS2 / Pt / SnO2.

[0034] Furthermore, the acid solution mentioned in step (1) is one or a mixture of sulfuric acid, nitric acid or hydrochloric acid.

[0035] Furthermore, the temperature of the hydrothermal reaction in step (2) is 120–160°C, and the reaction time is 4–12 hours.

[0036] Furthermore, the inert atmosphere described in step (4) is nitrogen or argon, the calcination temperature is 300-800℃, and the calcination time is 1-6 hours.

[0037] Furthermore, the ultrasonic power in steps (6) and / or (17) is 60 to 100 W, and the ultrasonic duration is 0.5 to 2 hours.

[0038] Furthermore, after adding sodium hydroxide solution in step (7), the pH of the alkaline environment is between 9 and 12.

[0039] Furthermore, the drying temperature in steps (10), (15) and (20) is 50-80°C, and the vacuum drying time is 12-24 hours.

[0040] Furthermore, the microwave heating power in step (18) is 100-700W, and the microwave heating time is 5-20 minutes.

[0041] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows:

[0042] (1) The electrolytic water cathode catalyst of the present invention improves the existing preparation process of loading Pt particles on a support. The electrolytic water cathode catalyst of the present invention is loaded with two layers of noble metal Pt nanoparticles. The first layer of noble metal Pt nanoparticles uses SnO2 as the support matrix, and the second layer of noble metal Pt nanoparticles uses MoS2 as the support matrix. The stability and conductivity of Pt particles are utilized between the two supports to form a multilayer structure, and the electrochemical activity is improved by utilizing the plasmon resonance effect. Pt nanoparticles are introduced by hydrothermal method, liquid phase reduction method and microwave method to achieve uniform distribution of Pt nanoparticles on the support matrix, expand the reaction area of ​​the catalyst, increase the number of active sites to promote the electrocatalytic reaction. While achieving a small amount of Pt nanoparticle loading on the matrix, it promotes electron transfer between interfaces, reduces the amount of noble metal used, reduces the catalyst cost and improves the catalyst activity.

[0043] (2) The electrolytic water catalyst of the present invention incorporates conductive SnO2 and MoS2 with excellent electron transport capability as Pt support, which reduces the amount of precious metal Pt and is conducive to reducing the local overpotential of the cathode.

[0044] (3) The electrolytic water cathode catalyst of the present invention is loaded with noble metals by liquid phase reduction and microwave method, and the plasma resonance effect of noble metals is used to optimize the electron transport pathway, form a stable catalyst structure and improve the electrochemical performance of the catalyst. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the preparation process of the electrolytic water cathode catalyst of the present invention.

[0046] Figure 2 The graph shows a comparison of the electrochemical performance of the catalysts prepared in Examples 1-2 and Comparative Examples 1-2. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0048] Example 1

[0049] A method for preparing a cathode catalyst for water electrolysis includes the following steps:

[0050] SnO2 pretreatment

[0051] (1) Weighing of materials: Weigh 1g SnO2 and add it to 100mL of 0.2M dilute sulfuric acid and stir for 2 hours;

[0052] (2) Provide an etching environment: Place the solution from step (1) in a 120°C reactor for hydrothermal treatment for 12 hours;

[0053] (3) Removal of impurity ions: Wash the solid sample obtained in step (2) with deionized water until the washing solution is neutral;

[0054] (4) Catalyst drying: The solid sample obtained after cleaning in step (3) is placed in a tube furnace and calcined at 500°C for 3 hours in a N2 atmosphere, and then cooled with the furnace to obtain roughened SnO2.

[0055] Pt / SnO2 loading

[0056] (5) Weighing of materials: Weigh chloroplatinic acid and glucose. The mass ratio of chloroplatinic acid: SnO2: glucose is 0.1:1:0.5, and the mass content of platinum in chloroplatinic acid is 37.5%.

[0057] (6) Feeding: Prepare a 0.5M solution of glucose from step (5), then add SnO2 and chloroplatinic acid, and sonicate for 0.5h to mix evenly;

[0058] (7) Adjust pH: Add 0.1M sodium hydroxide solution to the solution in step (6) until the pH of the solution is 11, while stirring continuously;

[0059] (8) Pt reduction: Add 10 mL of 0.1 M sodium borohydride solution to the solution in step (7) at a rate of 20 mL / min, and stir for 0.5 h to reduce Pt;

[0060] (9) Removal of impurity ions: Wash the solid sample from step (8) with a large amount of deionized water to remove excess impurity ions;

[0061] (10) Catalyst drying: The solid sample from step (9) was placed in a vacuum drying oven and heated at 80°C for 12 hours to dry it, thus obtaining Pt / SnO2.

[0062] Preparation of MoS2-supported Pt / SnO2

[0063] (11) Weighing of materials: Weigh sodium molybdate and thioacetamide separately. The mass ratio of sodium molybdate, thioacetamide and Pt / SnO2 is 0.5:1:1.

[0064] (12) Feeding: Dissolve sodium molybdate and thioacetamide from step (11) in 100 mL of deionized water and stir for 1 h to form a transparent solution. Then add Pt / SnO2 from step (10) and continue stirring for 0.5 to 2 h.

[0065] (13) Growth of MoS2: The solution from step (12) was placed in a reactor and reacted at 200°C for 18 hours, and then cooled with the furnace.

[0066] (14) Removal of impurity ions: Wash the solid sample obtained in step (13) with a large amount of deionized water to remove excess impurity ions;

[0067] (15) Catalyst drying: The solid sample from step (14) was placed in a vacuum drying oven at 80°C and heated for 12 hours to dry it, thus obtaining MoS2 / Pt / SnO2.

[0068] Preparation of Pt-supported MoS2 / Pt / SnO2

[0069] (16) Weighing of materials: Weigh chloroplatinic acid according to the mass ratio Pt:MoS2 / Pt / SnO2=1:33, wherein the mass content of platinum in chloroplatinic acid is 37.5%;

[0070] (17) Feeding: Place the MoS2 / Pt / SnO2 from step (15) in an ethylene glycol solution and sonicate for 0.5 h, then add the platinum precursor from step (16) and continue stirring for 4 h;

[0071] (18) Pt microwave reduction: The solution from step (17) is reduced by microwave for 5 minutes and 500W.

[0072] (19) Removal of impurity ions: Wash the solid sample obtained in step (18) with a large amount of deionized water to remove excess impurity ions;

[0073] (20) Catalyst drying: The solid sample from step (19) was placed in a vacuum drying oven and heated at 50°C for 12 hours to dry, and the finished catalyst Pt / MoS2 / Pt / SnO2 was obtained. The mass content of the noble metal Pt in the catalyst was 5.4%. The finished catalyst Pt / MoS2 / Pt / SnO2 was used as the cathode catalyst for water electrolysis.

[0074] Example 2

[0075] A method for preparing a cathode catalyst for water electrolysis includes the following steps:

[0076] SnO2 pretreatment

[0077] (1) Weighing of materials: 5g SnO2 by molar ratio, add to 200mL of 1M dilute nitric acid and stir for 6 hours;

[0078] (2) Provide an etching environment: Place the solution from step (1) in a reactor and perform hydrothermal treatment at 160°C for 6 hours;

[0079] (3) Removal of impurity ions: Wash the solid sample obtained in step (2) with deionized water until the pH of the washing solution is neutral;

[0080] (4) Catalyst drying: The solid sample washed in step (3) was placed in a tube furnace and calcined at 600°C for 2 hours in an Ar2 atmosphere, and then cooled with the furnace to obtain roughened SnO2.

[0081] Pt / SnO2 loading

[0082] (5) Weighing of materials: Weigh platinum nitrate and glucose according to the mass ratio of platinum nitrate: SnO2: glucose, wherein the mass content of platinum nitrate is 10%;

[0083] (6) Feeding: Prepare a 0.2M solution of glucose from step (5), then add SnO2 and platinum nitrate, and sonicate for 1 hour to mix evenly;

[0084] (7) Adjust pH: Add 1M sodium hydroxide solution to the solution in step (6) to adjust pH = 11, and stir continuously.

[0085] (8) Pt reduction: Add 10 ml of 1 M sodium borohydride solution to the solution in step (7) at a rate of 20 mL / min, and stir for 1 h to reduce Pt;

[0086] (9) Removal of impurity ions: Wash the solid sample from step (8) with a large amount of deionized water to remove excess impurity ions;

[0087] (10) Catalyst drying: The solid sample washed in step (9) was placed in a vacuum drying oven and heated at 60°C for 24 hours to dry, thus obtaining Pt / SnO2.

[0088] Preparation of MoS2-supported Pt / SnO2

[0089] (11) Weighing of materials: Weigh sodium molybdate, thioacetamide and Pt / SnO2 respectively according to the mass ratio 1:2:1.

[0090] (12) Feeding: Dissolve sodium molybdate and thioacetamide from step (11) in 250 mL of deionized water and stir for 2 h to form a transparent solution. Then add Pt / SnO2 from step (10) and continue stirring for 1 h.

[0091] (13) Growth of MoS2: The solution from step (12) was placed in a reactor and reacted at 180°C for 24 hours, and then cooled with the furnace.

[0092] (14) Removal of impurity ions: Wash the solid sample obtained in step (13) with a large amount of deionized water to remove excess impurity ions;

[0093] (15) Catalyst drying: The solid sample washed in step (14) was placed in a vacuum drying oven and heated at 60°C for 24 hours to dry it, thus obtaining MoS2 / Pt / SnO2.

[0094] Preparation of Pt-supported MoS2 / Pt / SnO2

[0095] (16) Weighing of materials: Weigh platinum nitrate according to the mass ratio Pt:MoS2 / Pt / SnO2=1:20, wherein the mass content of platinum nitrate is 10%;

[0096] (17) Feeding: Place the catalyst from step (15) in an ethylene glycol solution and sonicate for 2 hours. Then add the platinum precursor from step (16) and continue stirring for 8 hours.

[0097] (18) Pt microwave reduction: The solution from step (17) was microwaved for 20 minutes and 350W.

[0098] (19) Removal of impurity ions: Wash the solid sample obtained in step (18) with a large amount of deionized water to remove excess impurity ions;

[0099] (20) Catalyst drying: The solid sample from step (19) was placed in a vacuum drying oven and heated at 50°C for 12 hours to dry, and the finished catalyst Pt / MoS2 / Pt / SnO2 was obtained. The mass content of the noble metal Pt in the catalyst was 5.3%. The finished catalyst Pt / MoS2 / Pt / SnO2 was used as the cathode catalyst for water electrolysis.

[0100] Comparative Example 1

[0101] A method for preparing a cathode catalyst for water electrolysis includes the following steps:

[0102] Preparation of Pt / SnO2

[0103] (1) Weighing the material: Take 1g of SnO2 and add it to 100mL of 0.2M dilute sulfuric acid and stir for 2 hours;

[0104] (2) Provide an etching environment: Place the solution from step (1) in a reactor and perform hydrothermal treatment at 120°C for 12 hours;

[0105] (3) Removal of impurity ions: Wash the solid sample obtained in step (2) with deionized water until the pH of the washing solution is neutral;

[0106] (4) Catalyst drying: The solid catalyst in step (3) is placed in a tube furnace and calcined at 500°C for 3 hours in a N2 atmosphere, and then cooled with the furnace to obtain roughened SnO2.

[0107] (5) Weighing of materials: Weigh chloroplatinic acid and glucose according to the mass ratio of chloroplatinic acid: SnO2: glucose = 57:375:50. The mass content of platinum in chloroplatinic acid is 37.5% by mass fraction.

[0108] (6) Feeding: Prepare a 0.5M solution of glucose from step (5), then add SnO2 and chloroplatinic acid, and sonicate for 0.5h to mix evenly;

[0109] (7) Adjust pH: Add 0.1M sodium hydroxide solution to the solution in step (6) until pH = 11, and stir continuously;

[0110] (8) Pt reduction: Add 10 mL of 0.1 M sodium borohydride solution to the solution in step (7) at a rate of 20 mL / min, and stir for 0.5 h to reduce Pt;

[0111] (9) Removal of impurity ions: Wash the solid sample from step (8) with a large amount of deionized water to remove excess impurity ions;

[0112] (10) Catalyst drying: The solid sample from step (9) was placed in a vacuum drying oven and heated at 80°C for 12 hours to dry, resulting in Pt / SnO2, wherein the mass content of the noble metal Pt in the catalyst was 5.4%.

[0113] Comparative Example 2

[0114] A method for preparing a cathode catalyst for water electrolysis includes the following steps:

[0115] Preparation of Pt / MoS2

[0116] (1) Material weighing: Weigh 1g of sodium molybdate and 2g of thioacetamide according to the mass ratio of sodium molybdate:thioacetamide = 1:2;

[0117] (2) Feeding: Dissolve sodium molybdate and thioacetamide from step (1) in 250 mL of deionized water and stir for 2 h to form a transparent solution;

[0118] (3) Growth of MoS2: The solution from step (2) was placed in a reactor and reacted at 180°C for 24 hours, and then cooled with the furnace.

[0119] (4) Removal of impurity ions: Wash the solid sample obtained in step (3) with a large amount of deionized water to remove excess impurity ions;

[0120] (5) Catalyst drying: The solid sample from step (4) was placed in a vacuum drying oven and heated at 60°C for 24 hours to dry it, thus obtaining MoS2;

[0121] (6) Weighing of materials: Weigh chloroplatinic acid according to the mass ratio of chloroplatinic acid:MoS2 = 19:125. The mass content of platinum in chloroplatinic acid is 37.5%.

[0122] (7) Feeding: Place the MoS2 from step (5) in an ethylene glycol solution and sonicate for 2 hours. Then add the chloroplatinic acid from step (6) and continue stirring for 1 hour.

[0123] (8) Pt microwave reduction: The solution from step (7) is reduced by microwave for 20 minutes and 350W.

[0124] (9) Removal of impurity ions: Wash the solid sample obtained in step (8) with a large amount of deionized water to remove excess impurity ions;

[0125] (10) Catalyst drying: The solid sample from step (9) was placed in a vacuum drying oven and heated at 50°C for 12 hours to dry, and the finished catalyst Pt / MoS2 was obtained, wherein the mass content of the noble metal Pt in the catalyst was 5.4%.

[0126] The catalytic activity of the catalysts prepared in Examples 1-2 and Comparative Examples 1-2 was evaluated. The kinetics of the electrocatalytic hydrogen evolution reaction were assessed by overpotential analysis. Electrochemical tests were performed in a conventional three-electrode system, with a platinum wire as the counter electrode and Ag / AgCl as the reference electrode. The catalyst sample was dispersed in a 5 wt% Nafion@(Aldrich) isopropanol aqueous solution and then fixed onto a glassy carbon electrode to form the working electrode. Cyclic voltammetry (scan rate 50 mV / s) and linear sweep voltammetry were obtained at room temperature (25 °C) in a 0.1 mol / L perchloric acid electrolyte.

[0127] Electrochemical activity is determined using two parameters: (1) the onset of hydrogen release and (2) the current density at a constant current density (-10 mA*cm). -2 The voltage applied to NHE was measured, and the test results are as follows: Figure 2 As shown, with the same mass content of the noble metal Pt in the catalyst, the catalysts prepared in Examples 1 and 2 have a similar performance at -10 mA*cm. -2 The corresponding voltage is about 25mV lower than that of Comparative Example 1 and Comparative Example 2. Generally speaking, the closer the voltage is to 0V, the better the electrochemical performance.

[0128] The electrolytic water cathode catalyst prepared by this invention is used in a PEM electrolysis device. The SnO2 matrix is ​​roughened to make the Pt nanoparticles grow more stably on the SnO2 matrix surface. The strongly attached noble metal Pt particles can also promote the uniform distribution of MoS2 on the matrix surface and reduce interfacial resistance. The last layer of Pt nanoparticles promotes the transfer of electrons between interfaces and utilizes the plasmon resonance effect to improve the electrochemical performance of the catalyst, which is beneficial to hydrogen evolution.

[0129] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A cathode catalyst for water electrolysis, characterized in that, The catalyst comprises a SnO2 matrix, on which a first layer of noble metal Pt is loaded to obtain Pt / SnO2; MoS2 nanosheets are loaded on the surface of the Pt / SnO2 to obtain MoS2 / Pt / SnO2; a second layer of noble metal Pt is loaded on the surface of the MoS2 / Pt / SnO2 to obtain Pt / MoS2 / Pt / SnO2; wherein the loading amount of the first layer of noble metal Pt is 1-5% of the mass of the SnO2 matrix, the loading amount of the MoS2 nanosheets is 50-80% of the mass of Pt / SnO2, and the loading amount of the second layer of noble metal Pt is 1-10% of the mass of MoS2 / Pt / SnO2; and the Pt / MoS2 / Pt / SnO2 is used as a cathode catalyst for water electrolysis.

2. The method for preparing the electrolytic water cathode catalyst according to claim 1, characterized in that, Includes the following steps: SnO2 pretreatment (1) Weighing of materials: Weigh 1-10g of SnO2 and add it to a 0.2-2M acid solution and stir for 2-12 hours to form a solution; (2) Provide an etching environment: Place the solution from step (1) in a reaction vessel for hydrothermal treatment to obtain a solid sample; (3) Removal of impurity ions: Wash the solid sample obtained in step (2) with deionized water until the washing solution is neutral; (4) Catalyst drying: The solid sample cleaned in step (3) is placed in a tube furnace, calcined in an inert atmosphere and then cooled with the furnace to obtain roughened SnO2; Pt / SnO2 loading (5) Weighing of materials: Weigh the required amount of platinum precursor and glucose; (6) Feeding: Prepare a 0.05-0.5M solution of the glucose weighed in step (5), then add SnO2 and platinum precursor, sonicate for 0.5-2 hours, and mix evenly; (7) Adjust pH: Add 0.1~2M sodium hydroxide solution to the solution in step (6) until the solution is alkaline, and stir continuously; (8) Pt reduction: Add 10 mL of 0.05~1M sodium borohydride solution to the solution in step (7) and stir for 0.5~6 h to reduce Pt to obtain a solid sample; (9) Removal of impurity ions: Wash the solid sample from step (8) with deionized water to remove excess impurity ions; (10) Catalyst drying: The solid sample washed in step (9) is placed in a vacuum drying oven and kept for 12~24h to obtain Pt / SnO2; Preparation of MoS2-supported Pt / SnO2 (11) Weighing of materials: Weigh sodium molybdate and thioacetamide separately, wherein the mass ratio of sodium molybdate:thioacetamide:Pt / SnO2 is 1~3:1~4:1; (12) Feeding: Dissolve the sodium molybdate and thioacetamide weighed in step (11) in 100~500mL of deionized water and stir for 1~4h to form a transparent solution. Then add the Pt / SnO2 in step (10) and continue stirring for 0.5~2h. (13) Growth of MoS2: The solution from step (12) was placed in a reaction vessel and reacted at 180~220℃ for 12~24h. After that, it was cooled with the furnace to obtain a solid sample. (14) Removal of impurity ions: Wash the solid sample described in step (13) with deionized water to remove excess impurity ions; (15) Catalyst drying: The solid sample cleaned in step (14) is placed in a vacuum drying oven and kept for 12~24h to obtain MoS2 / Pt / SnO2; Preparation of Pt-supported MoS2 / Pt / SnO2 (16) Weighing of materials: Weigh the required amount of platinum precursor; (17) Feeding: Place the MoS2 / Pt / SnO2 described in step (15) in an ethylene glycol solution and sonicate for 0.5 to 2 hours. Then add the platinum precursor weighed in step (16) and continue stirring for 2 to 12 hours. (18) Pt microwave reduction: The solution from step (17) is reduced by microwave heating; (19) Removal of impurity ions: Wash the solid sample obtained in step (18) with deionized water to remove excess impurity ions; (20) Catalyst drying: The solid sample from step (19) is placed in a vacuum drying oven and heated for 12-24 hours to obtain the finished catalyst, denoted as Pt / MoS2 / Pt / SnO2.

3. The method for preparing the electrolytic water cathode catalyst according to claim 2, characterized in that, The acid solution mentioned in step (1) is one or a mixture of sulfuric acid, nitric acid or hydrochloric acid.

4. The method for preparing the electrolytic water cathode catalyst according to claim 2, characterized in that, The temperature of the hydrothermal reaction in step (2) is 120~160℃, and the reaction time is 4~12 hours.

5. The method for preparing the cathode catalyst for water electrolysis according to claim 2, characterized in that, The inert atmosphere mentioned in step (4) is nitrogen or argon, the calcination temperature is 300~800℃, and the calcination time is 1~6 hours.

6. The method for preparing the electrolytic water cathode catalyst according to claim 2, characterized in that, The ultrasonic power in steps (6) and / or (17) is 60~100W and the ultrasonic duration is 0.5~2 hours.

7. The method for preparing the cathode catalyst for water electrolysis according to claim 2, characterized in that, After adding sodium hydroxide solution in step (7), the pH of the alkaline environment is between 9 and 12.

8. The method for preparing the cathode catalyst for water electrolysis according to claim 2, characterized in that, The drying temperature in steps (10), (15) and (20) is 50~80℃, and the vacuum drying time is 12~24h.

9. The method for preparing the electrolytic water cathode catalyst according to claim 2, characterized in that, The microwave heating power in step (18) is 100-700W, and the microwave heating time is 5-20 minutes.

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