Hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst, preparation method thereof and electrolytic water device

Abstract

The present application provides a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst, a preparation method thereof, and an electrolytic water device, relating to the field of catalysts for electrolytic water. The hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst includes: a porous substrate, and a main catalytic structure located on the substrate, where the main catalytic structure includes a topologically insulating layer and a Bi<subgt;2< / subgt;S<subgt;3< / subgt; layer stacked. In the catalyst of the present application, the porous structure of the porous substrate can increase the reaction active area of the composite material, Bi<subgt;2< / subgt;S<subgt;3< / subgt; can improve the material stability, the topological insulator material can reduce the carrier recombination efficiency, and form a high-speed electron-hole transport channel, improving the separation and transport efficiency of carriers. The porous substrate, the topologically insulating layer, and the Bi<subgt;2< / subgt;S<subgt;3< / subgt> layer of the present application cooperate with each other, and have an efficient catalytic effect on both the OER reaction and the HER reaction.

Description

Technical Field

[0001] The present application relates to the field of catalysts for electrolytic water, and particularly to a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst, a preparation method thereof, and an electrolytic water device. Background Art

[0002] Compared with traditional fossil fuels, hydrogen energy has significant advantages such as high combustion calorific value, environmental friendliness, renewable, and wide sources. It is the most potential green energy in recent years and will undoubtedly gradually replace fossil fuels and become the pillar of future energy. Currently, electrocatalytic water splitting technology (electrolytic water) is considered one of the simplest hydrogen production technologies. This technology includes oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In the electrocatalytic water splitting system, the energy efficiency and stability of the reaction are important evaluation indicators for hydrogen production and oxygen production in electrolytic water. The use of catalysts can change the electron transfer path and reaction energy barrier in the electrocatalytic process, thereby effectively reducing the reaction overpotential and improving the conversion efficiency of hydrogen production and gas production in electrolytic water.

[0003] Currently, the most widely used catalysts are mainly Pt-based noble metal catalysts. Noble metal materials exhibit excellent performance in the field of electrocatalytic hydrogen production. However, due to the low reserves of noble metals and non-renewable resources, the cost of the catalysts remains high, which limits their development and utilization in electrolytic water.

[0004] In recent years, transition metals and their compounds have received widespread attention from researchers due to their abundant reserves, low cost, and long-term durability, providing more possibilities for the selection of electrolytic water catalysts. Currently, there have been reports of non-noble metal catalysts with excellent performance for electrolytic water. For example, oxides of transition metals such as iron, cobalt, and nickel are efficient oxygen evolution catalysts, while their sulfides, phosphides, nitrides, carbides, etc. are considered excellent electrocatalysts for hydrogen evolution reactions. However, it is still difficult to use the same catalyst for both hydrogen evolution and oxygen evolution reactions. Moreover, non-noble metal-based transition metal-based catalysts usually have the defect of complex preparation processes, and at the same time, toxic or dangerous raw materials such as hydrazine hydrate are usually used in the preparation process, causing certain pollution to the environment and being unfavorable for sustainable development. In view of the need to reduce the cost of electrolytic water and improve the catalytic efficiency, developing a non-noble metal bifunctional high-efficiency catalyst with low cost and simple preparation process is an urgent problem to be solved currently. Summary of the Invention

[0005] The purpose of the present application is to provide a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst, a preparation method thereof, and an electrolytic water device to solve the above problems.

[0006] To achieve the above objectives, the present application adopts the following technical solutions:

[0007] A hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst, comprising: a porous substrate, and a main catalytic structure located on the substrate, the main catalytic structure comprising a topologically insulating layer and a Bi2S3 layer arranged in a stacked manner.

[0008] According to an embodiment of the present application, the topologically insulating layer is located between the porous substrate and the Bi2S3 layer, or the Bi2S3 layer is located between the porous substrate and the topologically insulating layer.

[0009] According to an embodiment of the present application, the porous substrate comprises foam molybdenum nickel.

[0010] According to an embodiment of the present application, the material forming the topologically insulating layer comprises any one of Bi2Te3, Bi2Se3, and Bi2Se2Te.

[0011] The present application also provides a preparation method of the hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst as described above, comprising:

[0012] Forming a main catalytic structure on a porous substrate by a solvothermal method to obtain a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst; wherein, the main catalytic structure comprises a topologically insulating layer and a Bi2S3 layer arranged in a stacked manner.

[0013] According to an embodiment of the present application, the forming of the main catalytic structure on the porous substrate by the solvothermal method comprises:

[0014] Mixing a porous substrate, a bismuth source, a sulfur source, and ethylene glycol, and performing a first solvothermal reaction in a reaction kettle to obtain a composite structure of the porous substrate and Bi2S3;

[0015] Mixing a topologically insulating material precursor, the composite structure of the porous substrate and Bi2S3, and sodium hydroxide, and performing a second solvothermal reaction in a reaction kettle to obtain a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst.

[0016] According to an embodiment of the present application, the bismuth source comprises Bi(NO3)3 or a hydrate of Bi(NO3)3;

[0017] And / or, the sulfur source comprises at least one of thioacetamide, sodium sulfide nonahydrate, thiourea, and sodium sulfite;

[0018] And / or, the molar ratio of the bismuth source to the sulfur source is 1:(11 - 13);

[0019] And / or, the temperature of the first solvothermal reaction is 170 - 190 °C, and the time of the first solvothermal reaction is 11 - 13 h;

[0020] And / or, the topological insulator precursor includes Bi2O3 and TeO2, and the molar ratio of Bi2O3 to TeO2 is 1:(2 - 4);

[0021] And / or, the molar ratio of the bismuth source to Bi2O3 is 2:(0.9 - 1.1);

[0022] And / or, the molar ratio of Bi2O3 to sodium hydroxide is 1:(18 - 22);

[0023] And / or, when performing the second solvothermal reaction, the method further includes adding PVP to the reaction system, and the mass ratio of Bi2O3 to PVP is 0.233:(0.4 - 0.6);

[0024] And / or, the temperature of the second solvothermal reaction is 170 - 190 °C, and the time of the second solvothermal reaction is 23 - 25 h.

[0025] According to an embodiment of the present application, the formation of the main catalytic structure on the porous substrate by the solvothermal method includes:

[0026] Mixing the porous substrate, the topological insulator precursor, ethylene glycol, and sodium hydroxide, and performing a third solvothermal reaction in a reaction kettle to obtain a composite structure of the porous substrate and the topological insulator;

[0027] Mixing the bismuth source, the sulfur source, the composite structure of the porous substrate and the topological insulator, and ethylene glycol, and performing a fourth solvothermal reaction in a reaction kettle to obtain a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst.

[0028] According to an embodiment of the present application, the topological insulator precursor includes Bi2O3 and TeO2, and the molar ratio of Bi2O3 to TeO2 is 1:(2 - 4);

[0029] And / or, the molar ratio of Bi2O3 to sodium hydroxide is 1:(18 - 22);

[0030] And / or, when performing the third solvothermal reaction, the method further includes adding PVP to the reaction system, and the mass ratio of Bi2O3 to PVP is 0.233:(0.4 - 0.6);

[0031] And / or, the temperature of the third solvothermal reaction is 170 - 190 °C, and the time of the third solvothermal reaction is 23 - 25 h;

[0032] And / or, the bismuth source includes Bi(NO3)3 or a hydrate of Bi(NO3)3;

[0033] And / or, the sulfur source includes at least one of thioacetamide, sodium sulfide nonahydrate, thiourea, and sodium sulfite;

[0034] And / or, the molar ratio of the bismuth source to the sulfur source is 1:(11 - 13);

[0035] And / or, the molar ratio of the bismuth source to the Bi2O3 is 2:(0.9 - 1.1);

[0036] And / or, the temperature of the fourth solvothermal reaction is 170 - 190 °C, and the time of the fourth solvothermal reaction is 11 - 13 h.

[0037] This application also provides an electrolytic water device, and the electrolytic water device includes the hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst described above.

[0038] Compared with the prior art, the beneficial effects of this application include:

[0039] In the catalyst of this application, the porous structure of the porous substrate can increase the reaction active area of the composite material, Bi2S3 can improve the material stability, the topological insulator material can reduce the carrier recombination efficiency, and form an electron-hole high-speed transmission channel, enhancing the separation and transmission efficiency of carriers. The porous substrate, topological insulating layer, and Bi2S3 layer of this application cooperate with each other and have an efficient catalytic effect on both the OER reaction and the HER reaction.

[0040] Moreover, compared with the traditional noble metal-based catalyst, the raw materials of the catalyst of this application are cheap and easily available, the production cost is low, and it is suitable for large-scale production. Compared with the commonly used non-noble metal-based transition metal catalyst, the catalyst of this application has the advantages of simple preparation process, low toxicity of raw materials, and no environmental pollution. The topological surface state of the catalyst of this application can significantly reduce the overpotential of the catalytic reaction and significantly enhance the catalytic performance. At the same time, this composite material can achieve efficient catalysis for both the OER reaction and the HER reaction in an alkaline environment.

[0041] This application only needs two-step solvothermal method to prepare a high-performance catalyst. The material growth is simple, the production cost is low, and large-scale production is expected to be realized. The method of this application has the advantages of cheap and easily available raw materials and simple process. Moreover, the preparation method of this application also has the advantage of being green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of this application, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as limiting the scope of this application.

[0043] Figure 1In one embodiment of the present application, it is a schematic structural diagram of a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst;

[0044] Figure 2 In another embodiment of the present application, it is a schematic structural diagram of a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst;

[0045] Figure 3 It is an XRD pattern of Bi2Te3 prepared in Preparation Example 1;

[0046] Figure 4 It is an SEM image of Bi2Te3 prepared in Preparation Example 1;

[0047] Figure 5 It is an XRD pattern of Bi2S3 prepared in Preparation Example 2;

[0048] Figure 6 It is an SEM image of the cross-section of the Bi2Te3-Bi2S3-NMF composite material prepared in Example 1;

[0049] Figure 7 It is an SEM image of the cross-section of the Bi2S3-Bi2Te3-NMF composite material prepared in Example 2;

[0050] Figure 8 It is an SEM image of the raw material NMF used in Comparative Example 1;

[0051] Figure 9 It is an SEM image of Bi2Te3-NMF prepared in Comparative Example 1;

[0052] Figure 10 It is an SEM image of Bi2Te3-NMF prepared in Comparative Example 1;

[0053] Figure 11 It is a comparative chart of LSV curves of NMF, the materials of Examples 1-2 and Comparative Example 1 for HER reaction;

[0054] Figure 12 It is a comparative chart of LSV curves of NMF, the materials of Examples 1-2 and Comparative Example 1 for OER reaction. Detailed implementation manners

[0055] As used herein, the terms:

[0056] "Prepared from..." is synonymous with "comprising". As used herein, the terms "comprising", "including", "having", "containing" or any other variation thereof are intended to cover non-exclusive inclusion. For example, a composition, step, method, article or device containing the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article or device.

[0057] The connecting term "consisting of" excludes any unrecited element, step, or component. If used in a claim, this phrase will render the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause within the body of a claim rather than immediately following the subject, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0058] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, it should be understood that all ranges formed by any pairing of any upper range limit or preferred value with any lower range limit or preferred value are specifically disclosed, whether or not the range is separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted as including the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range.

[0059] In these examples, unless otherwise specified, the parts and percentages are by mass.

[0060] "Part by mass" refers to the basic measurement unit representing the mass ratio relationship of multiple components. 1 part can represent any unit mass, such as 1 g or 2.689 g, etc. If we say that the mass part of component A is a parts and the mass part of component B is b parts, it means the mass ratio of component A to component B is a:b. Or, it means the mass of component A is aK and the mass of component B is bK (K is any number representing a multiple factor). It should not be misunderstood that, different from the number of mass parts, the sum of the mass parts of all components is not limited to 100 parts.

[0061] "And / or" is used to indicate that either or both of the stated circumstances may occur. For example, A and / or B includes (A and B) and (A or B).

[0062] This application provides a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst, comprising: a porous substrate, and a main catalytic structure located on the substrate, wherein the main catalytic structure comprises a topologically insulating layer and a Bi2S3 layer stacked.

[0063] This application uses a topologically insulating layer combined with a sulfide to construct a heterostructure as the catalyst main body, which can effectively increase the specific surface area, increase the active sites, and improve the catalyst performance. Moreover, the composite of the topological insulator material and the sulfide, while improving the stability of the composite material, ensures the effective utilization of the efficient carrier channels of the topological insulator material.

[0064] The topological insulating layer can provide high carrier mobility. As a buffer interface, Bi2S3 can ensure the stability of the catalyst. By combining the topological insulating layer and the Bi2S3 layer in this application, the performance of the catalyst can be improved. The catalyst of this application can not only improve the efficiency of the electrocatalytic reaction, ensure the stability of the composite catalyst, but also simultaneously achieve the dual-functional catalysis of HER and OER, and has good cyclic stability.

[0065] The catalyst of this application can be used not only for the HER reaction, but also for the OER reaction simultaneously, and catalyze the HER and OER reactions simultaneously during the catalytic process. Its main principle is divided into two parts. Bi2S3 mainly acts as a buffer interface to improve the stability of the catalyst. The topological insulating layer mainly provides a fast carrier migration channel, thereby reducing the internal recombination of carriers in the HER and OER reactions and improving the reaction efficiency.

[0066] The difficulty in the research of highly efficient electrocatalytic hydrogen evolution catalysts lies in the preparation of high-quality heterogeneous materials. In this application, a topological insulator material and a bismuth sulfide material are compounded on a porous substrate. Through the topological surface state, the efficient transmission of carriers between materials can be ensured, which is also the basis for achieving a low overpotential in the catalytic reaction. The catalyst of this application can maintain the high activity of the catalyst while improving the hydrogen production efficiency.

[0067] Specifically, Bi2S3 in the catalyst of this application acts as a buffer interface to improve the material stability. The porous structure of the porous substrate can increase the reactive area of the composite material. The topological insulator material has the characteristic of rapid surface electron movement, which can reduce the carrier recombination efficiency and form a high-speed transmission channel for electron-hole, improving the separation and transmission efficiency of carriers, and finally obtaining a bifunctional electrolytic water catalyst with high catalytic performance.

[0068] According to an embodiment of this application, the topological insulating layer is located between the porous substrate and the Bi2S3 layer, or the Bi2S3 layer is located between the porous substrate and the topological insulating layer.

[0069] According to an embodiment of this application, the porous substrate includes nickel foam molybdenum. The porous structure of nickel foam molybdenum can increase the reactive area of the composite material. Compared with traditional materials, the nickel foam molybdenum substrate used in this application can increase the surface area of the composite material, increase the catalytic active sites, and at the same time efficiently utilize the high carrier migration channel of the topological surface state to improve the catalyst performance.

[0070] According to an embodiment of this application, the material forming the topological insulating layer includes any one of Bi2Te3, Bi2Se3, and Bi2Se2Te.

[0071] Further, the hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst may have Figure 1 or Figure 2 the structure shown.

[0072] The present application also provides a method for preparing the hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst as described above, including:

[0073] Forming a main catalytic structure on a porous substrate by a solvothermal method to obtain a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst; wherein, the main catalytic structure includes a stacked topological insulating layer and a Bi2S3 layer.

[0074] According to an embodiment of the present application, the forming of the main catalytic structure on the porous substrate by the solvothermal method includes:

[0075] Mixing the porous substrate, a bismuth source, a sulfur source, and ethylene glycol, and performing a first solvothermal reaction in a reaction kettle to obtain a composite structure of the porous substrate and Bi2S3;

[0076] Mixing a topological insulating material precursor, the composite structure of the porous substrate and Bi2S3, and sodium hydroxide, and performing a second solvothermal reaction in a reaction kettle to obtain a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst.

[0077] According to an embodiment of the present application, the bismuth source includes Bi(NO3)3 or a hydrate of Bi(NO3)3;

[0078] and / or, the sulfur source includes at least one of thioacetamide, sodium sulfide nonahydrate, thiourea, and sodium sulfite;

[0079] and / or, the molar ratio of the bismuth source to the sulfur source is 1:(11 - 13);

[0080] For example, the molar ratio of the bismuth source to the sulfur source can be 1:11, 1:12, 1:12.6, 1:13, or any value between 1:(11 - 13).

[0081] and / or, the temperature of the first solvothermal reaction is 170 - 190 °C, and the time of the first solvothermal reaction is 11 - 13 h;

[0082] For example, the temperature of the first solvothermal reaction can be 170 °C, 180 °C, 190 °C, or any value between 170 - 190 °C, and the time of the first solvothermal reaction can be 11 h, 12 h, 13 h, or any value between 11 - 13 h.

[0083] And / or, the topological insulating material precursor includes Bi2O3 and TeO2, and the molar ratio of Bi2O3 to TeO2 is 1:(2 - 4); for example, the molar ratio of Bi2O3 to TeO2 can be 1:2, 1:3, 1:4, or any value between 1:(2 - 4).

[0084] And / or, the molar ratio of the bismuth source to Bi2O3 is 2:(0.9 - 1.1); for example, the molar ratio of the bismuth source to Bi2O3 can be 2:0.9, 2:1, 2:1.1, or any value between 2:(0.9 - 1.1).

[0085] And / or, the molar ratio of Bi2O3 to sodium hydroxide is 1:(18 - 22); for example, the molar ratio of Bi2O3 to sodium hydroxide can be 1:18, 1:19, 1:20, 1:21, 1:22, or any value between 1:(18 - 22).

[0086] And / or, when performing the second solvothermal reaction, the method further includes adding PVP to the reaction system, and the mass ratio of Bi2O3 to PVP is 0.233:(0.4 - 0.6); for example, the mass ratio of Bi2O3 to PVP can be 0.233:0.4, 0.233:0.5, 0.233:0.6, or any value between 0.233:(0.4 - 0.6).

[0087] And / or, the temperature of the second solvothermal reaction is 170 - 190 °C, and the time of the second solvothermal reaction is 23 - 25 h.

[0088] For example, the temperature of the second solvothermal reaction can be 170 °C, 180 °C, 190 °C, or any value between 170 - 190 °C, and the time of the second solvothermal reaction can be 23 h, 24 h, 25 h, or any value between 23 - 25 h.

[0089] According to the embodiments of the present application, the formation of the main catalytic structure on the porous substrate by the solvothermal method includes:

[0090] Mixing the porous substrate, the topological insulating material precursor, ethylene glycol, and sodium hydroxide, and performing a third solvothermal reaction in a reaction kettle to obtain a composite structure of the porous substrate and the topological insulating material;

[0091] Mixing the bismuth source, the sulfur source, the composite structure of the porous substrate and the topological insulating material, and ethylene glycol, and performing a fourth solvothermal reaction in a reaction kettle to obtain a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst.

[0092] According to an embodiment of the present application, the topological insulating material precursor includes Bi2O3 and TeO2, and the molar ratio of Bi2O3 to TeO2 is 1:(2 - 4); for example, the molar ratio of Bi2O3 to TeO2 can be 1:2, 1:3, 1:4, or any value between 1:(2 - 4).

[0093] And / or, the molar ratio of Bi2O3 to sodium hydroxide is 1:(18 - 22); for example, the molar ratio of Bi2O3 to sodium hydroxide can be 1:18, 1:19, 1:20, 1:21, 1:22, or any value between 1:(18 - 22).

[0094] And / or, when performing the third solvothermal reaction, the method further includes adding PVP to the reaction system, and the mass ratio of Bi2O3 to PVP is 0.233:(0.4 - 0.6); for example, the mass ratio of Bi2O3 to PVP can be 0.233:0.4, 0.233:0.5, 0.233:0.6, or any value between 0.233:(0.4 - 0.6).

[0095] And / or, the temperature of the third solvothermal reaction is 170 - 190 °C, and the time of the third solvothermal reaction is 23 - 25 h;

[0096] For example, the temperature of the third solvothermal reaction can be 170 °C, 180 °C, 190 °C, or any value between 170 - 190 °C, and the time of the third solvothermal reaction can be 23 h, 24 h, 25 h, or any value between 23 - 25 h.

[0097] And / or, the bismuth source includes Bi(NO3)3 or a hydrate of Bi(NO3)3;

[0098] And / or, the sulfur source includes at least one of thioacetamide, sodium sulfide nonahydrate, thiourea, and sodium sulfite;

[0099] And / or, the molar ratio of the bismuth source to the sulfur source is 1:(11 - 13); for example, the molar ratio of the bismuth source to the sulfur source can be 1:11, 1:12, 1:12.6, 1:13, or any value between 1:(11 - 13).

[0100] And / or, the molar ratio of the bismuth source to Bi2O3 is 2:(0.9 - 1.1); for example, the molar ratio of the bismuth source to Bi2O3 can be 2:0.9, 2:1, 2:1.1, or any value between 2:(0.9 - 1.1).

[0101] And / or, the temperature of the fourth solvothermal reaction is 170 - 190 °C, and the time of the fourth solvothermal reaction is 11 - 13 h.

[0102] For example, the temperature of the fourth solvothermal reaction can be 170 °C, 180 °C, 190 °C, or any value between 170 - 190 °C, and the time of the fourth solvothermal reaction can be 11 h, 12 h, 13 h, or any value between 11 - 13 h.

[0103] The present application also provides an electrolytic water device, and the electrolytic water device includes the hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst described above.

[0104] The following will describe in detail the implementation schemes of the present application with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the embodiments, the operations are carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0105] Preparation Example 1: Preparation of Bi2Te3

[0106] Preparation Example 1 provides a method for preparing Bi2Te3. The sample is reacted in a 50 ml polytetrafluoroethylene inner liner at 180 °C for 24 h by the solvothermal method to obtain Bi2Te3 nanosheets, which specifically includes the following steps:

[0107] (1) Weigh 0.5 g of PVP and dissolve it in 33 ml of ethylene glycol, and continuously stir for 20 min;

[0108] (2) Weigh 0.233 g of Bi2O3, 0.239 g of TeO2, and 0.4 g of NaOH and add them to the stirred solution in (1), and continuously stir for 3 h;

[0109] (3) Transfer the solution to a polytetrafluoroethylene inner liner, put the inner liner into a reaction kettle, and then transfer it to an electrothermal blast drying oven for reaction at 180 °C for 24 h;

[0110] (4) After the reaction is cooled, transfer the solution to a centrifuge tube, and wash it multiple times with acetone, absolute ethanol, and deionized water at 10,000 revolutions for 10 min;

[0111] (5) After the washing is completed, transfer it to an electrothermal blast drying oven and place it at 85 °C for 12 h to dry, obtaining Bi2Te3 powder.

[0112] It can be seen that Figure 3 using the method of Preparation Example 1 can successfully prepare Bi2Te3. It can be seen that Figure 4 the Bi2Te3 nanosheets prepared by the method of Preparation Example 1 have good crystal quality.

[0113] Preparation Example 2: Preparation of Bi2S3 Material

[0114] Preparation Example 2 provides a method for preparing Bi2S3, which includes the following steps:

[0115] (1) Weigh 0.485 g of Bi(NO3)3·5H2O and dissolve it in 15 ml of ethylene glycol solution, and stir for 15 min;

[0116] (2) Weigh 0.95 g of thioacetamide and dissolve it in 15 ml of ethylene glycol solution by stirring until completely dissolved;

[0117] (3) Drop the solution in step (2) into the solution in step (1), and stir the mixed solution for another 20 min;

[0118] (4) Transfer the mixed solution in step (3) to a polytetrafluoroethylene inner liner. After placing the inner liner in a reaction kettle, transfer it to an electrothermal blast drying oven and react at 180 °C for 12 h;

[0119] (5) After the reaction is cooled down, transfer the solution to a centrifuge tube, and wash it repeatedly with acetone, absolute ethanol, and deionized water at 10,000 revolutions for 10 min;

[0120] (6) After the washing is completed, transfer it to an electrothermal blast drying oven and place it at 85 °C for 12 h to dry, obtaining Bi2S3 powder.

[0121] Figure 5 XRD pattern of Bi2S3 prepared in Preparation Example 2, from Figure 5 It can be seen that Bi2S3 was successfully prepared in Preparation Example 2.

[0122] Example 1

[0123] Example 1 provides a method for preparing a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst Bi2Te3-Bi2S3-NMF, which includes the following steps:

[0124] (1) Cut the molybdenum nickel foam into small pieces of (0.5 - 2)*(0.5 - 2) cm, place it in 3 M / L dilute hydrochloric acid and perform ultrasonic treatment for 5 - 15 min to remove the oxide layer. After rinsing with deionized water 5 - 10 times, then add the substrate to acetone and perform ultrasonic treatment for 5 - 15 min to remove the surface organic matter. Take out the substrate and perform ultrasonic treatment with absolute ethanol again for 5 - 15 min to remove the acetone residue. Rinse with deionized water again 5 - 10 times, and then place it in an electrothermal blast drying oven at 30 - 50 °C to dry for later use;

[0125] (2) Weigh 0.485 g of Bi(NO3)3·5H2O and dissolve it in 15 ml of ethylene glycol solution, and stir for 15 min;

[0126] (3) Weigh 0.95 g of thioacetamide and dissolve it in 15 ml of ethylene glycol solution, and stir until completely dissolved;

[0127] (4) Drop the solution in step (3) into the solution in step (2), and stir the mixed solution for another 20 min;

[0128] (5) Transfer the mixed solution in step (4) to a polytetrafluoroethylene inner liner, and add the foam metal that has been cleaned and dried in step (1). Put the inner liner into the reaction kettle and then transfer it to an electrothermal blast drying oven for reaction at 180 °C for 12 h;

[0129] (6) After the reaction temperature drops, take out the foam metal and wash it repeatedly with absolute ethanol and deionized water;

[0130] (7) After the washing is completed, transfer it to an electrothermal blast drying oven and place it at 55 °C for 12 h to dry, obtaining the Bi2S3-NMF composite material;

[0131] (8) Weigh 0.5 g of PVP and dissolve it in 33 ml of ethylene glycol, and continuously stir for 20 min;

[0132] (9) Weigh 0.233 g of Bi2O3, 0.239 g of TeO2, and 0.4 g of NaOH and add them to the stirred solution in (8), and continuously stir for 3 h;

[0133] (10) Transfer the solution to a polytetrafluoroethylene inner liner, and add the dried Bi2S3-NMF composite material in step (7). Put the inner liner into the reaction kettle and then transfer it to an electrothermal blast drying oven for reaction at 180 °C for 24 h;

[0134] (11) After the reaction temperature drops, take out the composite material and wash it repeatedly with absolute ethanol and deionized water;

[0135] (12) Transfer it to an electrothermal blast dryer and dry it at 55 °C to obtain the Bi2Te3-Bi2S3-NMF composite material, which is the hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst.

[0136] The SEM image of the cross-section of the Bi2Te3-Bi2S3-NMF composite material prepared in Example 1 is as Figure 6 shown, and it can be seen from Figure 6 that there is an obvious layered structure. The top layer is Bi2Te3 nanoflowers, the middle layer is Bi2S3, and the bottom layer is NMF foam metal.

[0137] Example 2

[0138] Example 2 provides a preparation method of a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst Bi2S3-Bi2Te3-NMF, including the following steps:

[0139] (1) Cut the molybdenum nickel foam into small pieces of (0.5 - 2) * (0.5 - 2) cm, place them in 3 M / L dilute hydrochloric acid, and ultrasonically treat for 5 - 15 min to remove the oxide layer. After rinsing with deionized water 5 - 10 times, add the substrate to acetone and ultrasonically treat for 5 - 15 min to remove surface organic substances. Take out the substrate and ultrasonically treat with absolute ethanol for another 5 - 15 min to remove acetone residues. Rinse with deionized water 5 - 10 times again, and then place it in an electrothermal blast drying oven at 30 - 50 °C for drying for later use;

[0140] (2) Weigh 0.5 g of PVP and dissolve it in 33 ml of ethylene glycol, and continuously stir for 20 min;

[0141] (3) Weigh 0.233 g of Bi2O3, 0.239 g of TeO2, and 0.4 g of NaOH and add them to the stirred solution in (2), and continuously stir for 3 h;

[0142] (4) Transfer the solution to a polytetrafluoroethylene inner liner, and add the dried NMF substrate in step (1). Put the inner liner into the reaction kettle and then transfer it to an electrothermal blast drying oven for reaction at 180 °C for 24 h;

[0143] (5) After the reaction temperature drops, take out the composite material and wash it repeatedly with absolute ethanol and deionized water;

[0144] (6) Transfer it to an electrothermal blast dryer and dry it at 55 °C to obtain Bi2Te3 - NMF;

[0145] (7) Weigh 0.485 g of Bi(NO3)3·5H2O and dissolve it in 15 ml of ethylene glycol solution and stir for 15 min;

[0146] (8) Weigh 0.95 g of thioacetamide and dissolve it in 15 ml of ethylene glycol solution and stir until completely dissolved;

[0147] (9) Drop the solution in step (8) into the solution in step (7), and stir the mixed solution for another 20 min;

[0148] (10) Transfer the mixed solution in step (9) to a polytetrafluoroethylene inner liner, and add the foam metal washed and dried in step (6). Put the inner liner into the reaction kettle and then transfer it to an electrothermal blast drying oven for reaction at 180 °C for 12 h;

[0149] (11) After the reaction temperature drops, take out the foam metal and wash it repeatedly with absolute ethanol and deionized water;

[0150] (12) After the washing is completed, transfer it to an electrothermal blast drying oven and place it at 55 °C for 12 h for drying to obtain the Bi2S3 - Bi2Te3 - NMF composite material, which is the hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst.

[0151] The SEM image of the cross-section of the Bi2S3-Bi2Te3-NMF composite material prepared in Example 2 is as follows Figure 7 shown, and it can be seen from Figure 7 that there is an obvious layered structure. The top layer is Bi2S3 nanorods, the middle layer is Bi2Te3, and the bottom layer is NMF foam metal.

[0152] Comparative Example 1

[0153] Comparative Example 1 provides a preparation method of a composite material of Bi2Te3 nanosheets and foam molybdenum-nickel metal. The sample is reacted for 24 h at 180 °C using a 50 ml polytetrafluoroethylene inner liner by a solvothermal method to obtain a composite material of Bi2Te3 nanosheets and foam molybdenum-nickel metal, which specifically includes the following steps:

[0154] (1) Cut the molybdenum-nickel foam into small pieces of (0.5-2)*(0.5-2) cm, place it in 3 M / L dilute hydrochloric acid and ultrasonically treat it for 5-15 min to remove the oxide layer. After rinsing with deionized water 5-10 times, add the substrate to acetone and ultrasonically treat it for 5-15 min to remove the surface organic matter. Take out the substrate and ultrasonically treat it with absolute ethanol again for 5-15 min to remove the acetone residue. Rinse it with deionized water again 5-10 times, and then place it in an electrothermal blast drying oven at 30-50 °C for drying for later use;

[0155] (2) Weigh 0.5 g of PVP and dissolve it in 33 ml of ethylene glycol, and continuously stir for 20 min;

[0156] (3) Weigh 0.233 g of Bi2O3, 0.239 g of TeO2, and 0.4 g of NaOH and add them to the solution after stirring in step (2), and continuously stir for 3 h;

[0157] (4) Transfer the solution to a polytetrafluoroethylene inner liner and put in the dried foam metal substrate. After putting the inner liner into the reaction kettle, transfer it to an electrothermal blast drying oven and react at 180 °C for 24 h;

[0158] (5) After the reaction is cooled down, take out the foam metal and wash it repeatedly with absolute ethanol and deionized water;

[0159] (6) After the washing is completed, transfer it to an electrothermal blast drying oven and place it at 85 °C for 12 h to dry, obtaining the Bi2Te3-NMF composite material.

[0160] Figure 8 The SEM image of the raw material NMF used in Comparative Example 1 is shown. It can be seen from Figure 8 that the surface of the original NMF substrate is flat and smooth after washing, without obvious impurities.

[0161] Figure 9SEM image of Bi2Te3-NMF prepared in Comparative Example 1, from Figure 9 it can be seen that after the solvothermal reaction, Bi2Te3 is uniformly and smoothly combined with the substrate, showing obvious stratification.

[0162] Figure 10 SEM image of Bi2Te3-NMF prepared in Comparative Example 1, from Figure 10 it can be seen that Bi2Te3 combined on the NMF substrate presents a hydrangea shape and is evenly distributed.

[0163] Comparative Example 2

[0164] Comparative Example 2 provides a preparation method of Bi2S3-NMF composite material, including the following steps:

[0165] (1) Cut molybdenum nickel foam into small pieces of (0.5-2)*(0.5-2) cm, place it in 3M / L dilute hydrochloric acid and ultrasonically treat for 5-15 min to remove the oxide layer. After rinsing with deionized water 5-10 times, add the substrate to acetone and ultrasonically treat for 5-15 min to remove surface organic matter. Take out the substrate and ultrasonically treat it with absolute ethanol for 5-15 min again to remove acetone residue. Rinse with deionized water 5-10 times again, and place it in an electrothermal blast drying oven at 30-50 °C for drying for later use;

[0166] (2) Weigh 0.485 g of Bi(NO3)3·5H2O and dissolve it in 15 ml of ethylene glycol solution and stir for 15 min;

[0167] (3) Weigh 0.95 g of thioacetamide and dissolve it in 15 ml of ethylene glycol solution by stirring until completely dissolved;

[0168] (4) Drop the solution in step (3) into the solution in step (2), and stir the mixed solution for another 20 min;

[0169] (5) Transfer the mixed solution in step (4) and the foam metal in step (1) to a polytetrafluoroethylene inner liner. After putting the inner liner into the reaction kettle, transfer it to an electrothermal blast drying oven and react at 180 °C for 12 h;

[0170] (6) After the reaction is cooled down, take out the foam metal and wash it repeatedly with absolute ethanol and deionized water;

[0171] (7) After the washing is completed, transfer it to an electrothermal blast drying oven and place it at 55 °C for 12 h to dry, obtaining Bi2S3-NMF composite material.

[0172] Figure 11 、 Figure 12And the test conditions in Table 1: The carbon rod and the saturated calomel electrode are used as the counter electrode and the reference electrode respectively, and the catalyst prepared in this application is used as the working electrode. The test is carried out at room temperature in 1M KOH electrolyte using a three-electrode system (linear sweep voltammetry, LSV).

[0173] Table 1 is a comparison table of overpotentials of HER reaction and OER reaction of NMF, Examples 1-2 and Comparative Examples 1-2 catalysts at a current density of 10 mA.

[0174] Table 1 Comparison table of overpotentials of HER reaction and OER reaction of NMF, Examples 1-2 and Comparative Examples 1-2 catalysts at a current density of 10 mA

[0175]

[0176] From Figure 11 、 Figure 12 and Table 1, it can be seen that compared with NMF and Comparative Examples 1-2, the catalysts of Examples 1-2 can simultaneously have a lower overpotential for HER reaction and a lower overpotential for OER reaction. Specifically, after NMF is compounded with bismuth telluride, the reaction overpotential is significantly reduced and the catalytic ability is significantly enhanced. Before adding bismuth sulfide, partial detachment of Bi2Te3-NMF occurred after the test, and the detachment situation improved after introducing bismuth sulfide. The catalysts of Examples 1-2 have excellent catalytic ability for both OER and HER reactions, and the results show that the catalysts of Examples 1-2 can be used as efficient bifunctional electrolytic water catalysts for oxygen evolution and hydrogen evolution under alkaline conditions.

[0177] Table 2 is a comparison table of the catalytic performance of the catalyst of this application and the reported existing catalysts.

[0178] Table 2 Comparison table of the catalytic performance of the catalyst of this application and the reported existing catalysts

[0179]

[0180] It can be seen from Table 2 that compared with the reported electrolytic water catalysts, the catalyst of this application has a lower overpotential for OER reaction, and at the same time the catalyst of this application also has a lower overpotential for HER reaction.

[0181] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of this application.

[0182] In addition, those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not others, the combination of features of different embodiments is meant to be within the scope of this application and forms different embodiments. For example, in the claims above, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is only for the purpose of enhancing the understanding of the overall background art of this application and should not be regarded as an admission or any form of suggestion that this information constitutes prior art already known to those skilled in the art.

Claims

1. A hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst, characterized in that, It includes: a porous substrate, and a main catalytic structure located on the substrate, the main catalytic structure including a topologically insulating layer and a Bi2S3 layer arranged in a stacked manner; the porous substrate includes foam molybdenum nickel.

2. The hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst according to claim 1, wherein The topologically insulating layer is located between the porous substrate and the Bi2S3 layer, or the Bi2S3 layer is located between the porous substrate and the topologically insulating layer.

3. The hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst according to claim 1 or 2, wherein The material forming the topologically insulating layer includes any one of Bi2Te3, Bi2Se3, and Bi2Se2Te.

4. A method for preparing a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst according to any one of claims 1-3, characterized in that, It includes: Using a solvothermal method to form a main catalytic structure on a porous substrate to obtain a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst; wherein, the main catalytic structure includes a topologically insulating layer and a Bi2S3 layer arranged in a stacked manner.

5. The preparation method of the hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst according to claim 4, wherein, The forming of the main catalytic structure on the porous substrate by the solvothermal method includes: Mixing the porous substrate, a bismuth source, a sulfur source, and ethylene glycol, and performing a first solvothermal reaction in a reaction kettle to obtain a composite structure of the porous substrate and Bi2S3; Mixing a topologically insulating material precursor, the composite structure of the porous substrate and Bi2S3, and sodium hydroxide, and performing a second solvothermal reaction in a reaction kettle to obtain a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst.

6. The preparation method of the hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst according to claim 5, characterized in that, The bismuth source includes Bi(NO3)3 or a hydrate of Bi(NO3)3; and / or, the sulfur source includes at least one of thioacetamide, sodium sulfide nonahydrate, thiourea, and sodium sulfite; and / or, the molar ratio of the bismuth source to the sulfur source is 1:(11 - 13); and / or, the temperature of the first solvothermal reaction is 170 - 190 °C, and the time of the first solvothermal reaction is 11 - 13 h; and / or, the topologically insulating material precursor includes Bi2O3 and TeO2, and the molar ratio of Bi2O3 to TeO2 is 1:(2 - 4); and / or, the molar ratio of the bismuth source to Bi2O3 is 2:(0.9 - 1.1); and / or, the molar ratio of Bi2O3 to sodium hydroxide is 1:(18 - 22); and / or, when performing the second solvothermal reaction, the method further includes adding PVP to the reaction system, and the mass ratio of Bi2O3 to PVP is 0.233:(0.4 - 0.6); and / or, the temperature of the second solvothermal reaction is 170 - 190 °C, and the time of the second solvothermal reaction is 23 - 25 h.

7. The preparation method of the hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst according to claim 4, wherein, The forming of the main catalytic structure on the porous substrate by the solvothermal method includes: Mixing the porous substrate, a topologically insulating material precursor, ethylene glycol, and sodium hydroxide, and performing a third solvothermal reaction in a reaction kettle to obtain a composite structure of the porous substrate and the topologically insulating material; Mixing a bismuth source, a sulfur source, the composite structure of the porous substrate and the topologically insulating material, and ethylene glycol, and performing a fourth solvothermal reaction in a reaction kettle to obtain a hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst.

8. The preparation method of the hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst according to claim 7, characterized in that, The topologically insulating material precursor includes Bi2O3 and TeO2, and the molar ratio of Bi2O3 to TeO2 is 1:(2 - 4); and / or, the molar ratio of Bi2O3 to sodium hydroxide is 1:(18 - 22); And / or, when performing the third solvothermal reaction, the method further includes adding PVP to the reaction system, and the mass ratio of Bi2O3 to PVP is 0.233:(0.4 - 0.6); And / or, the temperature of the third solvothermal reaction is 170 - 190 °C, and the time of the third solvothermal reaction is 23 - 25 h; And / or, the bismuth source includes Bi(NO3)3 or a hydrate of Bi(NO3)3; And / or, the sulfur source includes at least one of thioacetamide, sodium sulfide nonahydrate, thiourea, and sodium sulfite; And / or, the molar ratio of the bismuth source to the sulfur source is 1:(11 - 13); And / or, the molar ratio of the bismuth source to Bi2O3 is 2:(0.9 - 1.1); And / or, the temperature of the fourth solvothermal reaction is 170 - 190 °C, and the time of the fourth solvothermal reaction is 11 - 13 h.

9. An electrolyzed water device, characterized in that, The electrolytic water device includes the hydrogen evolution and oxygen evolution bifunctional electrolytic water catalyst according to any one of claims 1 - 3.

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