Tungstate / phosphide heterostructure nano-catalyst as well as preparation method and application thereof
Through the design of tungstate/phosphide heterostructure nanocatalysts, the problems of high cost and insufficient activity of traditional electrocatalysts are solved, and efficient and stable hydrogen production process of water electrolysis is achieved, and there are broad electrocatalytic application prospects.
Patent Information
- Application Number
- CN202411430626.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-14
- Publication Date
- 2025-01-17
AI Technical Summary
Traditional precious metal electrocatalysts are costly and have few reserves in the process of electrolyzing hydrogen production. The number and stability of non-precious metal electrocatalysts are insufficient in the hydrogen evolution and oxygen evolution reaction, which limits the efficiency of electrolyzing water reaction.
By designing tungstate/phosphide heterostructure nanocatalysts, using transition metal salts, tungsten salts and control agents for hydrothermal reaction, heat treatment and phosphating treatment, forming tungstate/phosphide heterojunction nanocatalysts, optimized their Electronic structure and active sites.
It significantly improves electrocatalytic activity and stability, reduces reaction overpotential, enhances the durability of the catalyst, reduces the preparation cost, and broadens the application range of electrocatalytic materials.
Smart Images
Figure CN119320962A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of nanomaterials, and in particular to a tungstate / phosphide heterostructure nanocatalyst and a method and application thereof. Background Art
[0002] Hydrogen energy has attracted much attention as a clean and efficient energy carrier. Hydrogen production by water electrolysis is considered to be one of the most promising ways to produce hydrogen. It can convert electrical energy into chemical energy and realize the storage and utilization of clean energy. However, the reaction kinetics of water electrolysis are slow, and efficient electrocatalysts are required to reduce the reaction overpotential and increase the reaction rate. Traditional precious metal electrocatalysts (such as platinum and iridium) have excellent electrocatalytic activity, but their scarce reserves and high costs limit their large-scale application. Therefore, the development of efficient and low-cost non-precious metal electrocatalysts has become a hot topic in current research. Transition metal compounds, such as phosphides, sulfides, nitrides, oxides, etc., are considered to be ideal electrocatalysts to replace precious metals due to their rich electronic structures and tunability. However, these single materials have weak adsorption energies for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) intermediates, and their stability, conductivity and number of active sites need to be improved.
[0003] Heterogeneous engineering is an advanced strategy to deal with these problems. Heterojunction refers to the close combination of two or more different materials at the atomic scale. Through the electronic interaction at the interface, a synergistic effect can be generated, thereby improving the electrocatalytic performance of the material. Because different components in the heterostructure usually have different electronegativity, this will drive electron transfer, optimize the interface charge distribution / electron transfer and the adsorption / desorption behavior of reaction intermediates. At the same time, different components have different lattice constants, and their hybridization will produce interface atoms with unsaturated coordination and higher energy; these interface atoms can serve as active centers to increase the number of electrocatalytic active sites. In particular, compared with traditional single-component catalysts, heterojunction catalysts have the advantages of higher electron transfer efficiency, synergy, reduced reaction overpotential, enhanced catalytic stability, increased active sites, and optimized electronic structure in the process of electrocatalytic water splitting. These characteristics significantly improve the catalytic performance, making it excellent in improving reaction efficiency and stability, thereby more efficiently promoting the process of hydrogen and oxygen production by water electrolysis.
[0004] In recent years, researchers have turned their attention to the construction of various heterojunctions. By building different types of materials into heterojunctions, the electronic structure of the material can be adjusted, the active sites can be optimized, and the intrinsic activity of the catalyst can be improved. However, the design and synthesis of tungstate / phosphide heterojunction nanocatalysts with excellent electrocatalytic performance are still rarely reported. Summary of the invention
[0005] In view of this, the purpose of the present application is to provide a tungstate / phosphide heterostructure nanocatalyst and its method and application.
[0006] In a first aspect, the present application provides a method for preparing a tungstate / phosphide heterostructure nanocatalyst, the preparation method comprising the following steps:
[0007] S1. dissolving a transition metal salt, a tungsten salt and a control agent in a solvent to form a solution;
[0008] S2, transferring the solution obtained in step S1 to a reactor for hydrothermal reaction to obtain reactant 1;
[0009] S3, heat-treating the reactant 1 to obtain a reactant 2;
[0010] S4, dissolving the reactant 2, the transition metal salt and the control agent in a solvent, and reacting them under magnetic stirring under oil bath conditions to obtain a reactant 3;
[0011] S5. In a protective atmosphere, the reactant 3 is subjected to phosphating treatment to obtain a tungstate / phosphide heterojunction nanocatalyst.
[0012] Preferably, the transition metal salt is selected from one or more of ferric chloride, ferric sulfate, ferric nitrate, ferric acetate, cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt acetate, nickel chloride, nickel sulfate, nickel nitrate, and nickel acetate.
[0013] Preferably, the tungsten salt is selected from one or more of sodium tungstate, potassium tungstate and ammonium tungstate;
[0014] The control agent is selected from one or more of urea, ammonium fluoride, sodium citrate, and polyvinyl pyrrolidone;
[0015] The solvent is selected from one or more of deionized water, ethanol, ethylene glycol, acetone, and N-methylpyrrolidone.
[0016] Preferably, in step S2, the reaction temperature of the hydrothermal reaction is 150-200° C., and the reaction time is 2-10 h.
[0017] Preferably, in step S3, the temperature of the heat treatment is 400-550°C.
[0018] Preferably, in step S4, the reaction temperature of the oil bath condition is 80-120° C., and the reaction time is 2-10 h.
[0019] Preferably, in step S5, the phosphating treatment comprises the following steps:
[0020] In a protective atmosphere, the reactant 3 and the phosphorus-containing compound are placed separately in a reactor for heating treatment, wherein the phosphorus-containing compound is located above the airflow, so that the phosphorus-containing compound is heated to produce phosphine to react with the reactant 3 to obtain a tungstate / phosphide heterojunction nanocatalyst;
[0021] Wherein, the protective atmosphere is selected from one of nitrogen, oxygen, argon or a hydrogen / argon mixture;
[0022] Wherein, the phosphorus-containing compound is phosphorus iodide and / or sodium hypophosphite.
[0023] Preferably, in step S5, the phosphating temperature of the phosphating treatment is 300-400°C, the heating rate is 2-8°C / min, and the phosphating time is 1-6h.
[0024] In a second aspect, the present application provides a tungstate / phosphide heterostructure nanocatalyst, wherein the tungstate / phosphide heterostructure nanocatalyst is prepared by any of the preparation methods described above.
[0025] In a third aspect, the present application provides an application of a tungstate / phosphide heterostructure nanocatalyst in catalytic hydrolysis to produce hydrogen, wherein the tungstate / phosphide heterostructure nanocatalyst is prepared by any of the preparation methods described above.
[0026] Compared with the prior art, the beneficial effects of this application are:
[0027] (1) Significantly improve electrocatalytic activity: The heterojunction structure formed by the two materials of tungstate and phosphide produces abundant defects and electronic states at the interface, which effectively promotes charge separation and transfer, reduces the overpotential of HER and OER, and significantly improves the catalytic activity;
[0028] (2) Enhanced catalyst stability: Traditional single-component catalysts are prone to structural degradation and deactivation during long-term water electrolysis. The heterojunction structure enhances the structural stability of the material and improves the durability of the catalyst during long-term electrochemical reactions. At the same time, the nanostructured structural design increases the specific surface area of the material, providing more active sites for the electrocatalytic reaction, thereby improving the stability of the catalyst;
[0029] (3) Reduce preparation cost: The tungstate / phosphide heterojunction structure used in the present invention uses cheap and abundant non-precious metal materials. In addition, the preparation method provided by the present invention is simple in process, low in cost, easy to prepare on a large scale, and has good industrial prospects;
[0030] (4) Broadened the application scope of electrocatalytic materials: Tungstate / phosphide heterojunction nanocatalysts have shown excellent performance in the field of hydrogen production by water electrolysis, providing new ideas for the development of new and efficient electrocatalytic materials, and also providing potential application prospects for other electrochemical reactions (such as oxygen reduction reaction, carbon dioxide reduction reaction, nitrogen reduction reaction, etc.).
[0031] In summary, the catalyst proposed in this application forms a tightly bound heterojunction structure at the nanoscale by precisely regulating the interface structure of tungstate and phosphide, thereby significantly improving the electrochemical activity and stability of the catalyst. The preparation method is simple, controllable, and has good repeatability. The prepared catalyst exhibits excellent performance in electrocatalytic water decomposition and has broad application prospects. The present invention provides a new idea for the development of efficient and stable new catalytic materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.
[0033] Figure 1 The NiWO prepared in Example 1 of the present application 4 -Ni 2 SEM image of P heterojunction nanocatalyst;
[0034] Figure 2 The NiWO prepared in Example 1 of the present application 4 -Ni 2 Transmission electron microscopy image of P heterojunction nanocatalyst;
[0035] Figure 3 The NiWO prepared in Example 1 of the present application 4 -Ni 2 XRD spectrum of P heterojunction nanocatalyst;
[0036] Figure 4 The NiWO prepared in Example 1 of the present application 4 -Ni 2 XPS full spectrum of P heterojunction nanocatalyst;
[0037] Figure 5 The NiWO prepared in Example 1 of the present application 4 -Ni 2 P heterojunction nanocatalyst and single component NiWO 4 And Ni 2Comparison of linear sweep voltammetry curves of P in 1M KOH;
[0038] Figure 6 The CoWO prepared in Example 2 of the present application 4 -SEM image of CoP heterojunction nanocatalyst;
[0039] Figure 7 The CoWO prepared in Example 2 of the present application 4 -XRD spectrum of CoP heterojunction nanocatalyst. DETAILED DESCRIPTION
[0040] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with embodiments. Several embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive:
[0041] The present application provides a method for preparing a tungstate / phosphide heterostructure nanocatalyst, the preparation method comprising the following steps:
[0042] S1. dissolving a transition metal salt, a tungsten salt and a control agent in a solvent to form a solution;
[0043] S2, transferring the solution obtained in step S1 to a reactor for hydrothermal reaction to obtain reactant 1;
[0044] S3, heat treating reactant 1 to obtain reactant 2;
[0045] S4, dissolving reactant 2, transition metal salt and control agent in a solvent, and reacting under magnetic stirring under oil bath conditions to obtain reactant 3;
[0046] S5. In a protective atmosphere, the reactant 3 is subjected to phosphating treatment to obtain a tungstate / phosphide heterojunction nanocatalyst.
[0047] In one embodiment, the transition metal salt is selected from one or more of ferric chloride, ferric sulfate, ferric nitrate, ferric acetate, cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt acetate, nickel chloride, nickel sulfate, nickel nitrate, and nickel acetate.
[0048] The inventors have found that among the many transition metal salts, not all transition metal salts can form the final tungstate / phosphide heterojunction nanocatalyst. Therefore, the selection of transition metal salts has an impact on the formation of the final tungstate / phosphide heterojunction nanocatalyst.
[0049] Specifically, in one embodiment, the tungsten salt is selected from one or more of sodium tungstate, potassium tungstate, and ammonium tungstate.
[0050] Specifically, in one embodiment, the control agent is selected from one or more of urea, ammonium fluoride, sodium citrate, and polyvinyl pyrrolidone.
[0051] Specifically, in one embodiment, the solvent is selected from one or more of deionized water, ethanol, ethylene glycol, acetone, and N-methylpyrrolidone.
[0052] Specifically, in one embodiment, in step S2, the reaction temperature of the hydrothermal reaction is 150-200°C, and the reaction time is 2-10h; wherein, when the temperature of the hydrothermal reaction is set too low, the reaction in step S2 is incomplete, resulting in incomplete formation of reactant 1, affecting the final yield and formation quality; when the temperature of the hydrothermal reaction is set too high, the inventors found that the by-products increase during the reaction, affecting the final catalyst yield and purity.
[0053] Specifically, in one embodiment, in step S3, the heat treatment temperature is 400-550°C; when the heat treatment temperature is too low, the inventors found that some nickel salt and tungstate remain in the product, thereby affecting the purity of the final product; and when the temperature is too high, NiWO 4 Phase changes may occur, affecting its physical and chemical properties.
[0054] Specifically, in one embodiment, in step S4, the reaction temperature of the oil bath condition is 80-120° C., and the reaction time is 2-10 h.
[0055] Specifically, in one embodiment, in step S5, the phosphating treatment includes the following steps:
[0056] In a protective atmosphere, the reactant 3 and the phosphorus-containing compound are placed separately in a reactor for heating treatment, wherein the phosphorus-containing compound is located above the gas flow, so that the phosphorus-containing compound is heated to produce phosphine to react with the reactant 3 to obtain a tungstate / phosphide heterojunction nanocatalyst;
[0057] Further, the protective atmosphere is selected from one of nitrogen, oxygen, argon or a hydrogen / argon mixture;
[0058] Furthermore, the phosphorus-containing compound is phosphorus iodide and / or sodium hypophosphite.
[0059] Specifically, in one embodiment, in step S5, the phosphating temperature of the phosphating treatment is 300-400°C, the heating rate is 2-8°C / min, and the phosphating time is 1-6h; wherein, the temperature of the phosphating treatment is set to 300-400°C. When the temperature is lower than this range, phosphide is not easily formed, resulting in low phosphating efficiency, prolonged reaction process and affecting the quality of the final product; and when the temperature is greater than this range, the inventors found that the loss of phosphorus increases rapidly, affecting the stoichiometric ratio of the product and increasing the production cost.
[0060] The present application also provides a tungstate / phosphide heterostructure nanocatalyst, which is prepared by any of the preparation methods described above.
[0061] The present application also provides an application of a tungstate / phosphide heterostructure nanocatalyst in catalytic hydrolysis to produce hydrogen. The tungstate / phosphide heterostructure nanocatalyst is prepared by any of the preparation methods described above.
[0062] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.
[0063] In the following embodiments, unless otherwise specified, all of them are conventional methods.
[0064] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.
[0065] Example 1
[0066] This embodiment provides a first tungstate / phosphide heterojunction nanocatalyst, and the preparation method thereof is as follows:
[0067] S1. Dissolve 3.0 mmol of nickel nitrate, 3.0 mmol of sodium tungstate and 20.0 mmol of urea in 80 mL of deionized water to form a solution;
[0068] S2, transferring the solution obtained in step S1 to a reaction kettle, reacting at 170° C. for 6 h, and then washing, filtering and drying in sequence to obtain reactant 1;
[0069] S3, placing the reactant 1 obtained in the above step S2 in a muffle furnace, heating the temperature from room temperature to 500°C at a heating rate of 5°C / min, and keeping the temperature at this temperature for 2.5h to obtain reactant 2, i.e. NiWO 4 ;
[0070] S4, the NiWO obtained in the above step S3 4, 3.0mmol nickel nitrate and 0.2mol urea were dissolved in 20mL deionized water and 30mL N-methylpyrrolidone, and reacted with magnetic stirring at 100℃ in an oil bath for 5h, and then washed, filtered and dried in sequence to obtain reactant 3;
[0071] S5, the reactant 3 obtained in step S4 and NaH 2 PO 2 ·H 2 O is placed on both sides of the quartz boat, where NaH 2 PO 2 ·H 2 O on the gas inlet side, place the quartz boat in a tube furnace, and heat the temperature from room temperature to 350°C at a rate of 3°C / min under nitrogen protection, and keep it at this temperature for 2h. 2 PO 2 ·H 2 PH generated by high temperature decomposition of O 3 The gas flows along the gas flow to the reactant 3 side and undergoes phosphating to obtain NiWO 4 -Ni 2 P heterojunction nanocatalyst.
[0072] The NiWO prepared above 4 -Ni 2 P heterojunction nanocatalyst was characterized and tested. The results are shown in Figures 1 to 5 shown.
[0073] Figure 1 The NiWO prepared in this example 4 -Ni 2 Scanning electron microscope image of P heterojunction nanocatalyst.
[0074] Figure 2 The NiWO prepared in this example 4 -Ni 2 Transmission electron microscopy image of P heterojunction nanocatalyst.
[0075] Figure 3 The NiWO prepared in this example 4 -Ni 2 XRD spectrum of P heterojunction nanocatalyst. From the XRD spectrum, it can be seen that the obtained sample contains NiWO 4 and Ni 2 The peak of P indicates that NiWO was successfully synthesized from XRD. 4 -Ni 2 P heterojunction catalyst.
[0076] Figure 4 The NiWO prepared in this example 4 -Ni2 XPS full spectrum of P heterojunction nanocatalyst. From the XPS full spectrum, it can be seen that Ni, W, O, and P elements are all present in the sample, which proves that NiWO was successfully synthesized. 4 -Ni 2 P heterojunction catalyst.
[0077] Figure 5 The NiWO prepared in Example 1 4 -Ni 2 P heterojunction nanocatalyst and single component NiWO 4 And Ni 2 Comparison of linear sweep voltammetric curves of P in 1M KOH. It can be seen from the figure that NiWO 4 -Ni 2 P heterojunction nanocatalyst is better than single-component NiWO 4 And Ni 2 P has better hydrogen evolution reaction performance.
[0078] Example 2
[0079] This embodiment provides a tungstate / phosphide heterojunction nanocatalyst, and the preparation method thereof is as follows:
[0080] S1. Dissolve 3.0 mmol of cobalt nitrate, 3.0 mmol of sodium tungstate and 20.0 mmol of urea in 80 mL of deionized water to form a solution;
[0081] S2, transferring the solution obtained in step S1 to a reaction kettle, reacting at 170° C. for 6 h, and then washing, filtering and drying in sequence to obtain reactant 1;
[0082] S3, placing the reactant 1 obtained in the above step S2 in a muffle furnace, heating the temperature from room temperature to 500°C at a heating rate of 5°C / min, and keeping the temperature at this temperature for 2.5h to obtain reactant 2, i.e., CoWO 4 ;
[0083] S4, the CoWO obtained in the above step S3 4 3.0mmol cobalt nitrate and 0.2mol urea were dissolved in 20mL ionized water and 30mL N-methylpyrrolidone, and reacted with magnetic stirring at 100℃ in an oil bath for 5h, and then washed, filtered and dried in sequence to obtain reactant 3;
[0084] S5, the reactant 3 obtained in step S4 and NaH 2 PO 2 ·H 2 O is placed on both sides of the quartz boat, where NaH 2 PO 2 ·H2 O on the gas inlet side, place the quartz boat in a tube furnace, and heat the temperature from room temperature to 350°C at a rate of 3°C / min under nitrogen protection, and keep it at this temperature for 2h. 2 PO 2 ·H 2 PH generated by high temperature decomposition of O 3 The gas flows along the gas flow to the reactant 3 side and undergoes phosphation to obtain CoWO 4 -CoP heterojunction nanocatalyst;
[0085] in, Figure 6 CoWO prepared in this example 4 -Scanning electron microscope image of CoP heterojunction nanocatalyst.
[0086] Figure 7 CoWO prepared in this example 4 -XRD spectrum of CoP heterojunction nanocatalyst. From the XRD spectrum, it can be seen that the obtained sample contains CoWO 4 The peaks of CoP and CoWO were confirmed by XRD. 4 -CoP heterojunction catalyst.
[0087] Example 3
[0088] This embodiment provides a tungstate / phosphide heterojunction nanocatalyst, and the preparation method thereof is as follows:
[0089] S1. Dissolve 3.0 mmol of nickel nitrate, 3.0 mmol of sodium tungstate and 20.0 mmol of urea in 80 mL of deionized water to form a solution;
[0090] S2, transferring the solution obtained in step S1 to a reaction kettle, reacting at 170° C. for 6 h, and then washing, filtering and drying in sequence to obtain reactant 1;
[0091] S3, placing the reactant 1 obtained in the above step S2 in a muffle furnace, heating the temperature from room temperature to 500°C at a heating rate of 5°C / min, and keeping the temperature at this temperature for 2.5h to obtain reactant 2, i.e. NiWO 4 ;
[0092] S4, the NiWO obtained in the above step S3 4 3.0mmol cobalt nitrate and 0.2mol urea were dissolved in 20mL ionized water and 30mL N-methylpyrrolidone, and reacted with magnetic stirring at 100℃ in an oil bath for 5h, and then washed, filtered and dried in sequence to obtain reactant 3;
[0093] S5, the reactant 3 obtained in step S4 and NaH2 PO 2 ·H 2 O is placed on both sides of the quartz boat, where NaH 2 PO 2 ·H 2 O on the gas inlet side, place the quartz boat in a tube furnace, and heat the temperature from room temperature to 350°C at a rate of 3°C / min under nitrogen protection, and keep it at this temperature for 2h. 2 PO 2 ·H 2 PH generated by high temperature decomposition of O 3 The gas flows along the gas flow to the reactant 3 side and undergoes phosphating to obtain NiWO 4 -CoP heterojunction nanocatalyst.
[0094] Example 4
[0095] This embodiment provides a tungstate / phosphide heterojunction nanocatalyst, and the preparation method thereof is as follows:
[0096] S1. Dissolve 3.0 mmol of cobalt nitrate, 3.0 mmol of sodium tungstate and 20.0 mmol of urea in 80 mL of deionized water to form a solution;
[0097] S2, transferring the solution obtained in step S1 to a reaction kettle, reacting at 170° C. for 6 h, and then washing, filtering and drying in sequence to obtain reactant 1;
[0098] S3, placing the reactant 1 obtained in the above step S2 in a muffle furnace, heating the temperature from room temperature to 500°C at a heating rate of 5°C / min, and keeping the temperature at this temperature for 2.5h to obtain reactant 2, namely CoWO 4 ;
[0099] S4, the CoWO obtained in the above step S3 4 , 3.0mmol nickel nitrate and 0.2mol urea were dissolved in 20mL ionized water and 30mL N-methylpyrrolidone, and reacted with magnetic stirring at 100℃ in an oil bath for 5h, and then washed, filtered and dried in sequence to obtain reactant 2;
[0100] S5, the reactant 3 obtained in step S4 and NaH 2 PO 2 ·H 2 O is placed on both sides of the quartz boat, where NaH 2 PO 2 ·H 2 O on the gas inlet side, place the quartz boat in a tube furnace, and heat the temperature from room temperature to 350°C at a rate of 3°C / min under nitrogen protection, and keep it at this temperature for 2h.2 PO 2 ·H 2 PH generated by high temperature decomposition of O 3 The gas flows along the gas flow to the reactant 3 side and undergoes phosphation to obtain CoWO 4 -Ni 2 P heterojunction nanocatalyst.
[0101] Comparative Example 1
[0102] This comparative example is based on Example 1, and different transition metal salts are selected for reaction. The specific preparation method is as follows:
[0103] S1. Dissolve 3.0 mmol of nickel nitrate, 3.0 mmol of sodium tungstate and 20.0 mmol of urea in 80 mL of deionized water to form a solution;
[0104] S2, transferring the solution obtained in step S1 to a reaction kettle, reacting at 170° C. for 6 h, and then washing, filtering and drying in sequence to obtain reactant 1;
[0105] S3, placing the reactant 1 obtained in the above step S2 in a muffle furnace, heating the temperature from room temperature to 500°C at a heating rate of 5°C / min, and keeping the temperature at this temperature for 2.5h to obtain reactant 2, i.e. NiWO 4 ;
[0106] S4, the NiWO obtained in the above step S3 4 3.0mmol zinc nitrate and 0.2mol urea were dissolved in 20mL deionized water and 30mL N-methylpyrrolidone, and reacted with magnetic stirring at 100℃ in an oil bath for 5h, and then washed, filtered and dried in sequence to obtain reactant 3;
[0107] S5, the reactant 3 obtained in step S4 and NaH 2 PO 2 ·H 2 O is placed on both sides of the quartz boat, where NaH 2 PO 2 ·H 2 O on the gas inlet side, place the quartz boat in a tube furnace, and heat the temperature from room temperature to 350°C at a rate of 3°C / min under nitrogen protection, and keep it at this temperature for 2h. 2 PO 2 ·H 2 PH generated by high temperature decomposition of O 3 The gas flows along the gas stream to the reactant 3 side and is phosphated.
[0108] The method of Comparative Example 1 cannot obtain NiWO 4 -Zn3 P 2 Heterojunction nanocatalysts.
[0109] Comparative Example 2
[0110] This comparative example is based on Example 1, and the temperature of the heat treatment in step S3 is adjusted. The specific preparation method is as follows:
[0111] S1. Dissolve 3.0 mmol of nickel nitrate, 3.0 mmol of sodium tungstate and 20.0 mmol of urea in 80 mL of deionized water to form a solution;
[0112] S2, transferring the solution obtained in step S1 to a reaction kettle, reacting at 170° C. for 6 h, and then washing, filtering and drying in sequence to obtain reactant 1;
[0113] S3, placing the reactant 1 obtained in the above step S2 in a muffle furnace, heating the temperature from room temperature to 300°C at a heating rate of 5°C / min, and keeping the temperature at this temperature for 2.5h to obtain a reactant 2;
[0114] S4, dissolving the reactant 2 obtained in the above step S3, 3.0 mmol nickel nitrate and 0.2 mol urea in 20 mL deionized water and 30 mL N-methylpyrrolidone, reacting with magnetic stirring at 100° C. in an oil bath for 5 h, and then washing, filtering and drying in sequence to obtain a reactant 3;
[0115] S5, the reactant 3 obtained in step S4 and NaH 2 PO 2 ·H 2 O is placed on both sides of the quartz boat, where NaH 2 PO 2 ·H 2 O on the gas inlet side, place the quartz boat in a tube furnace, and heat the temperature from room temperature to 350°C at a rate of 3°C / min under nitrogen protection, and keep it at this temperature for 2h. 2 PO 2 ·H 2 PH generated by high temperature decomposition of O 3 The gas flows along the gas stream to the reactant 3 side and is phosphated.
[0116] The comparative method cannot obtain NiWO 4 -Ni 2 P heterojunction nanocatalyst.
[0117] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.
[0118] The above description is only a preferred embodiment of the present application and does not constitute any form of limitation to the present application. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application are within the scope of the technical solution of the present application.
Claims
1. A method for preparing a tungstate / phosphide heterostructure nanocatalyst, characterized in that: The preparation method comprises the following steps: S1. dissolving a transition metal salt, a tungsten salt and a control agent in a solvent to form a solution; S2, transferring the solution obtained in step S1 to a reactor for hydrothermal reaction to obtain reactant 1; S3, heat-treating the reactant 1 to obtain a reactant 2; S4, dissolving the reactant 2, the transition metal salt and the control agent in a solvent, and reacting them under magnetic stirring under oil bath conditions to obtain a reactant 3; S5. In a protective atmosphere, the reactant 3 is subjected to phosphating treatment to obtain a tungstate / phosphide heterojunction nanocatalyst.
2. The preparation method according to claim 1, characterized in that: The transition metal salt is selected from one or more of ferric chloride, ferric sulfate, ferric nitrate, ferric acetate, cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt acetate, nickel chloride, nickel sulfate, nickel nitrate and nickel acetate.
3. The preparation method according to claim 1, characterized in that: The tungsten salt is selected from one or more of sodium tungstate, potassium tungstate and ammonium tungstate; The control agent is selected from one or more of urea, ammonium fluoride, sodium citrate, and polyvinyl pyrrolidone; The solvent is selected from one or more of deionized water, ethanol, ethylene glycol, acetone, and N-methylpyrrolidone.
4. The preparation method according to claim 1, characterized in that: In step S2, the reaction temperature of the hydrothermal reaction is 150-200°C, and the reaction time is 2-10h.
5. The preparation method according to claim 1, characterized in that: In step S3, the temperature of the heat treatment is 400-550°C.
6. The preparation method according to claim 1, characterized in that: In step S4, the reaction temperature of the oil bath condition is 80-120° C., and the reaction time is 2-10 h.
7. The preparation method according to claim 1, characterized in that: In step S5, the phosphating treatment comprises the following steps: In a protective atmosphere, the reactant 3 and the phosphorus-containing compound are placed separately in a reactor for heating treatment, wherein the phosphorus-containing compound is located above the airflow, so that the phosphorus-containing compound is heated to produce phosphine to react with the reactant 3 to obtain a tungstate / phosphide heterojunction nanocatalyst; Wherein, the protective atmosphere is selected from one of nitrogen, oxygen, argon or a hydrogen / argon mixture; Wherein, the phosphorus-containing compound is phosphorus iodide and / or sodium hypophosphite.
8. The preparation method according to claim 7, characterized in that: In step S5, the phosphating temperature of the phosphating treatment is 300-400°C, the heating rate is 2-8°C / min, and the phosphating time is 1-6h.
9. A tungstate / phosphide heterostructure nanocatalyst, characterized in that: The tungstate / phosphide heterostructure nanocatalyst is prepared by the preparation method according to any one of claims 1 to 8.
10. An application of a tungstate / phosphide heterostructure nanocatalyst in catalytic hydrolysis to produce hydrogen, characterized in that: The tungstate / phosphide heterostructure nanocatalyst is prepared by the preparation method according to any one of claims 1 to 7.