A molybdenum cation and phosphorus anion co-doped VS2 catalytic material, its preparation method and application in hydrogen evolution reaction

Abstract

The present invention discloses a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions, its preparation method, and its application in hydrogen evolution reactions, belonging to the technical field of electrocatalytic materials. The catalytic material is composed of micron-flowers uniformly grown on a carbon-based material; the micron-flowers are assembled from VS2 nanosheets co-doped with molybdenum cations and phosphorus anions. The preparation method involves first oxidizing the surface of the carbon-based material, then hydrothermally growing a molybdenum-doped vanadium disulfide material on the surface in situ, and then doping it with phosphorus through a heat treatment method. This yields a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions with excellent HER catalytic activity and cyclic stability. The preparation method is simple, low-cost, high-yield, mild, requires simple equipment, is environmentally friendly, and is conducive to industrial production.

Description

Technical Field

[0001] The present invention relates to a modified VS2 catalytic material, in particular to a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions, and also to a preparation method thereof and application in an electrocatalytic hydrogen evolution reaction, belonging to the technical field of electrocatalytic materials. Background Art

[0002] Commercial Pt-based HER catalysts are recognized as the most efficient catalysts for hydrogen production by water electrolysis due to their excellent catalytic activity and stability. However, Pt is a precious metal, and its high cost and low earth reserves severely limit the development of the water electrolysis hydrogen production industry. Therefore, the development of catalytic materials based on non-precious metal elements has become a hot topic in the field of water electrolysis catalytic materials.

[0003] At present, transition metal sulfides (TMDs) have attracted the interest of researchers due to their large specific surface area and high catalytic activity edge. As a representative of transition metal sulfides, vanadium disulfide (VS2) is considered to be a promising HER catalyst that can replace the precious metal Pt because of its metallic properties, catalytic activity at both the edge and in-plane, and low cost. The literature (Chemical Engineering Journal, 2020, 396: 125227) discloses that Mo cation doping can significantly enhance the in-plane hydrogen evolution activity of VS2, and in addition to Mo doping, metal cation doping with low hydrogen adsorption free energy such as Ni and Co has also been shown to enhance the HER activity of VS2, such as literature: (Small 2024, 2311217), (International Journal of Hydrogen Energy, 2022, 47 (19): 10646-10653.), (Journal of Materials Chemistry A, 2022, 10 (16): 9067-9079.) and so on. Currently, most vanadium disulfide or transition metal-doped vanadium disulfide materials are synthesized by hydrothermal methods. However, vanadium disulfide materials synthesized by hydrothermal methods generally have the technical problem of poor cyclic stability, for example, as reported in the literature (ACS applied materials & interfaces, 2017, 9(48): 42139-42148). Prior art reports show that doping vanadium disulfide materials with transition metal ions can improve their HER activity, but this does not solve the technical problem of poor stability. Summary of the Invention

[0004] In view of the defects of the prior art, the first object of the present invention is to provide a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions, which has not only good stability but also high HER catalytic activity.

[0005] The second object of the present invention is to provide a method for preparing a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions. The preparation method is simple, low-cost, and has a low synthesis temperature. It does not require large equipment and harsh reaction conditions and can achieve large-scale production.

[0006] The third object of the present invention is to provide an application of a VS2 catalyst material co-doped with molybdenum cations and phosphorus anions, which is used as an electrocatalytic active material in the electrocatalytic hydrogen evolution reaction, showing excellent hydrogen evolution performance and stability, for example, at 50 mA cm -2 The overpotential is as low as -0.2303 V (relative to standard hydrogen electrode) at the current density, and the Tafel slope is as low as 49.5 mV / dec. After 10,000 CV scans, the polarization curve is at 50 mA cm -2 The current density of the -2 After 120 hours of constant current polarization at the same current density, the overpotential only decayed by 40mV.

[0007] In order to achieve the above technical objectives, the present invention provides a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions, which is composed of micron flowers uniformly grown on a carbon-based material; the micron flowers are assembled from VS2 nanosheets co-doped with molybdenum cations and phosphorus anions.

[0008] The VS2 catalytic material co-doped with molybdenum cations and phosphorus anions exhibits a unique flower-like structure. The micron-sized flower-like structure is self-assembled from nanosheets of molybdenum cations and phosphorus anions co-doped with VS2 and uniformly grown on a carbon-based material. Using the carbon-based material as a carrier, the catalytic material achieves highly dispersed and stable loading of the catalytically active components, increasing their specific surface area and exposing more catalytically active sites, resulting in better catalytic activity and enhanced stability and conductivity. Nanosheet-like molybdenum cations and phosphorus anions co-doped VS2 self-assemble to form microflowers, which serve as the catalytic active component. The microflower structure has a large specific surface area and numerous exposed active sites, resulting in enhanced catalytic activity. Mo cation doping reduces the diameter of the microflowers, increases their specific surface area, modulates the electronic structure of vanadium disulfide, expands the interlayer spacing of the vanadium disulfide microflower structure, and increases the number of active sites, significantly improving their electrocatalytic hydrogen evolution activity and cyclic stability. In particular, simultaneous doping with phosphorus anions enhances hydrogen adsorption at S sites on the basal plane. However, it also inevitably strengthens hydrogen adsorption at S sites on the V edge, leading to over-binding of H* and hindering the HER at the V edge sites after Mo cation doping. Introducing phosphorus anions into Mo cation-doped VS2 compensates for the overly strong H* adsorption at the Mo cation-doped in-plane and edge sites, thereby moderately weakening their H* adsorption activity. Furthermore, it was unexpectedly found that phosphorus doping significantly improves the stability of Mo-doped vanadium disulfide.

[0009] As a preferred solution, the microflowers grow into a layered structure. The growth of microflowers into a layered structure can increase the number of catalytic active sites.

[0010] As a preferred solution, the carbon-based material is carbon cloth. The preferred carbon-based material is carbon cloth, which is flexible and has a porous structure, and is more suitable as a carrier material for the VS2 catalytic active component.

[0011] As a preferred embodiment, in the VS2 co-doped with molybdenum cations and phosphorus anions, the doping amount of molybdenum cations is measured at an atomic ratio of Mo to V of (0.05-0.15):(0.95-0.85), and the doping amount of phosphorus anions is measured at an atomic ratio of P to S of (0.01-0.15):(0.99-0.85). The hydrogen evolution performance of molybdenum-doped vanadium disulfide first increases and then decreases with the molybdenum doping amount, and the hydrogen evolution performance is close to the best when the molybdenum doping amount is 10%. On the other hand, when phosphorus anion doping is further performed on the basis of molybdenum doping, the hydrogen evolution performance of VS2 co-doped with molybdenum cations and phosphorus anions improves with increasing phosphorus doping amount. When the phosphorus anion content increases to a certain level, the hydrogen evolution performance shows a downward trend.

[0012] The molybdenum-doped vanadium disulfide micro-flower material of the present invention contains four elements: Mo, V, S, and P. Its physical phase is a single vanadium disulfide phase. Molybdenum cations are doped in the VS2 lattice to replace vanadium cations, and phosphorus anions are doped in the VS2 lattice to replace sulfur anions.

[0013] The present invention also provides a method for preparing a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions, the method comprising the following steps:

[0014] 1) performing oxidation pretreatment on the surface of the carbon-based material to obtain a pretreated carbon-based material;

[0015] 2) adding a molybdenum source, a vanadium source, and aqueous ammonia to water, stirring until transparent, and then adding a sulfur source and stirring to obtain a mixed solution; transferring the mixed solution into a reactor containing a pretreated carbon-based material, performing a hydrothermal reaction, and obtaining a molybdenum-doped vanadium disulfide material;

[0016] 3) Using sodium hypophosphite as a phosphorus source, phosphorus-doping the molybdenum-doped vanadium disulfide material is performed through a heat treatment method to obtain the obtained product.

[0017] The preparation method of the VS2 catalytic material co-doped with molybdenum cations and phosphorus anions of the present invention selects a carbon-based material as a carrier and performs surface oxidation pretreatment on the carbon-based material, which is conducive to achieving in-situ growth and highly dispersed loading of the VS2 catalytic active components on its surface. Then, a molybdenum-doped vanadium disulfide material is in-situ deposited on the surface of the carbon-based material by a hydrothermal method. The hydrothermal method can control the morphology of the VS2 crystal and the doping effect of the molybdenum cations, so that it forms a flower-like structure assembled by nanosheets, and the molybdenum cations can be uniformly doped in the VS2 lattice. Finally, the molybdenum-doped vanadium disulfide material is doped with phosphorus by a heat treatment method. The heat treatment method can achieve uniform and controllable doping of phosphorus.

[0018] As a preferred embodiment, the oxidation pretreatment process involves soaking the carbon-based material in a mixture of nitric acid and sulfuric acid. This preoxidation treatment generates oxygen-containing polar groups on the surface of the carbon-based material, thereby increasing its wettability with the solution and facilitating in-situ deposition. Furthermore, the polar groups can coordinate and bind to vanadium ions in the solution, promoting the in-situ growth of VS2 and preventing agglomeration. The nitric acid and sulfuric acid mixture is composed of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 2.5 to 3.5:1. The soaking time is preferably at least 12 hours.

[0019] As a preferred solution, the molybdenum source includes at least one of ammonium molybdate, sodium molybdate and potassium molybdate.

[0020] As a preferred solution, the vanadium source includes ammonium metavanadate and / or sodium vanadate.

[0021] As a preferred embodiment, the sulfur source includes thiourea and / or thioacetamide.

[0022] The molybdenum source, vanadium source, sulfur source and phosphorus source involved in the present invention are all conventional commercial reagents in the prior art.

[0023] As a preferred solution, the molybdenum source, vanadium source and sulfur source are measured according to the atomic ratio of molybdenum, vanadium and sulfur of (0.05-0.15): (0.95-0.85): (5-10).

[0024] As a preferred solution, the mass ratio of the phosphorus source to the molybdenum-doped vanadium disulfide material is 1.2 to 1.7:1.

[0025] As a preferred embodiment, the hydrothermal reaction conditions are: temperature of 140-220°C, time of 12-26 hours, most preferably temperature of 160-180°C, and time of 23-25 ​​hours.

[0026] As a preferred solution, the process of phosphorus-doping the molybdenum-doped vanadium disulfide material by heat treatment is as follows: sodium hypophosphite is placed in the upstream heating zone of the tube furnace, and the molybdenum-doped vanadium disulfide material is placed in the downstream heating zone of the tube furnace. An inert atmosphere is filled in the tube furnace, and the temperature of the upstream heating zone is controlled to be 300-350°C, and the temperature of the downstream heating zone is controlled to be 300-500°C. After keeping warm for 2-4 hours, the mixture is cooled to room temperature.

[0027] The preparation method of the VS2 catalytic material co-doped with molybdenum cations and phosphorus anions of the present invention is described below by way of example:

[0028] 1) First step: Carbon cloth (CC) treatment: Cut the carbon cloth into rectangular pieces of 1 cm × 1.5 cm in size, soak the carbon cloth in a mixture of nitric acid and sulfuric acid, ultrasonically wash it with deionized water and anhydrous ethanol for more than three times, and then dry it in a vacuum drying oven;

[0029] 2) The second step is to synthesize Mo-doped VS2: a molybdenum source, a vanadium source, and ammonia are added to water and stirred until transparent. A sulfur source is then added and stirred to obtain a mixed solution. A carbon cloth is then added as a growth substrate, and the mixture is subjected to a one-step hydrothermal reaction. The reaction product is washed and dried to obtain a molybdenum-doped vanadium disulfide precursor material.

[0030] 3) The third step is to perform P doping by heat treatment: sodium hypophosphite is used as the P doping source, and the sodium hypophosphite is placed in a magnetic boat at the center of the upstream heating zone of the tubular furnace. The above-mentioned molybdenum-doped vanadium disulfide precursor material is placed in the magnetic boat and placed in the center of the downstream heating zone; in an argon atmosphere, heating is carried out, and the temperatures of the upper temperature zone and the lower temperature zone are respectively 300°C and 300-500°C. After keeping warm for a period of time and cooling to room temperature, a VS2 electrocatalytic electrode material co-doped with molybdenum cations and phosphorus anions is obtained.

[0031] The drying involved in the present invention adopts vacuum freeze drying or vacuum drying at 50-80°C.

[0032] The present invention also provides an application of a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions, which is applied to an electrocatalytic hydrogen evolution reaction.

[0033] The VS2 catalyst material co-doped with molybdenum cations and phosphorus anions provided by the present invention is applied to the electrocatalytic hydrogen evolution reaction and exhibits excellent hydrogen evolution performance at 50 mA cm -2 The overpotential is as low as -0.2303 V (relative to standard hydrogen electrode) at the current density, and the Tafel slope is as low as 49.5 mV / dec. After 10,000 CV scans, the polarization curve is at 50 mA cm -2 The current density of the -2 After 120 hours of constant current polarization at the same current density, the overpotential only decayed by 40mV.

[0034] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:

[0035] 1) The molybdenum cation and phosphorus anion co-doped VS2 catalytic material provided by the present invention is composed of nano-sheet molybdenum cations and phosphorus anions co-doped VS2 self-assembled into a micron-sized flower-like structure uniformly grown on a carbon-based material, which exhibits high electrocatalytic hydrogen evolution activity and stability; at 50 mA cm -2 The overpotential is as low as -0.2303 V (relative to standard hydrogen electrode) at the current density, and the Tafel slope is as low as 49.5 mV / dec. After 10,000 CV scans, the polarization curve is at 50 mA cm -2 The current density of the -2 After 120 hours of constant current polarization at the same current density, the overpotential only decayed by 40mV.

[0036] 2) The preparation method of the molybdenum cation and phosphorus anion co-doped VS2 catalytic material provided by the present invention is simple, low-cost, and the reaction conditions are easy to control, which can meet the advantages of industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 These are the XRD patterns of the VS2 catalyst material co-doped with molybdenum cations and phosphorus anions in Examples 1 to 3 of the present invention, the Mo-doped VS2 catalyst material in Comparative Example 1, the P-doped VS2 catalyst material in Comparative Example 2, and the undoped vanadium disulfide catalyst material in Comparative Example 3.

[0038] Figure 2This is the SEM spectrum of the VS2 catalyst material co-doped with molybdenum cations and phosphorus anions in Example 1 of the present invention. Figure 3 This is the EDS surface scan analysis of the VS2 catalyst material co-doped with molybdenum cations and phosphorus anions in Example 1 of the present invention.

[0039] Figure 4 Polarization curves (after iR compensation) of the VS2 catalyst material co-doped with molybdenum cations and phosphorus anions in Examples 1 to 3 of the present invention, the Mo-doped VS2 catalyst material in Comparative Example 1, the P-doped VS2 catalyst material in Comparative Example 2, and the undoped vanadium disulfide catalyst material in Comparative Example 3 in 0.5 mol / L sulfuric acid solution.

[0040] Figure 5 These are the Tafel plots of the VS2 catalyst material co-doped with molybdenum cations and phosphorus anions in Examples 1 to 3 of the present invention, the Mo-doped VS2 catalyst material in Comparative Example 1, the P-doped VS2 catalyst material in Comparative Example 2, and the undoped vanadium disulfide catalyst material in Comparative Example 3 in 0.5 mol / L sulfuric acid solution.

[0041] Figure 6 This is the cyclic voltammetry curve of the VS2 hydrogen evolution electrocatalyst co-doped with molybdenum cations and phosphorus anions in Example 1 of the present invention in 0.5 mol / L sulfuric acid solution.

[0042] Figure 7 This is the cyclic voltammetry curve of the VS2 hydrogen evolution electrocatalyst co-doped with molybdenum cations and phosphorus anions in Example 2 of the present invention in 0.5 mol / L sulfuric acid solution.

[0043] Figure 8 This is the cyclic voltammetry curve of the VS2 hydrogen evolution electrocatalyst co-doped with molybdenum cations and phosphorus anions in Example 3 of the present invention in 0.5 mol / L sulfuric acid solution.

[0044] Figure 9 This is the cyclic voltammetry curve of the Mo-doped VS2 hydrogen evolution electrocatalyst in 0.5 mol / L sulfuric acid solution in Comparative Example 1 of the present invention.

[0045] Figure 10 This is the cyclic voltammetry curve of the P-doped VS2 hydrogen evolution electrocatalyst in 0.5 mol / L sulfuric acid solution in Comparative Example 2 of the present invention.

[0046] Figure 11 This is the cyclic voltammetry curve of pure VS2 hydrogen evolution electrocatalyst in 0.5 mol / L sulfuric acid solution in comparative embodiment 3 of the present invention.

[0047] Figure 12The capacitance current density-scan rate changes at a potential of 0.2 V are shown in the CV curves of the VS2 catalyst material co-doped with molybdenum cations and phosphorus anions in Examples 1 to 3 of the present invention, the Mo-doped VS2 catalyst material in Comparative Example 1, the P-doped VS2 catalyst material in Comparative Example 2, and the undoped vanadium disulfide catalyst material in Comparative Example 3 in 0.5 mol / L sulfuric acid solution. The straight line is the fitting result.

[0048] Figure 13 Polarization curves of the VS2 hydrogen evolution electrocatalyst co-doped with molybdenum cations and phosphorus anions in Example 1 of the present invention before and after CV stability in 0.5 mol / L sulfuric acid solution.

[0049] Figure 14 This is the voltage-time curve of the constant current polarization of the VS2 hydrogen evolution electrocatalyst co-doped with molybdenum cations and phosphorus anions in Example 1 of the present invention in a 0.5 mol / L sulfuric acid solution.

[0050] Figure 15 This is the SEM morphology of the undoped vanadium disulfide micro-flower material in Comparative Example 3 of the present invention.

[0051] Figure 16 This is the EDS surface scanning analysis of the undoped vanadium disulfide micro-flower material in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0052] In order to facilitate the understanding of the present invention, the present invention will be described in more comprehensive and detailed manner below in conjunction with the accompanying drawings and preferred embodiments.

[0053] Example 1:

[0054] 1) First step: Carbon cloth (CC) treatment: Cut the carbon cloth into rectangular pieces of 1 cm × 1.5 cm in size, soak the carbon cloth in a mixed acid of nitric acid and sulfuric acid (3:1) for more than 12 hours, then ultrasonically wash it with deionized water and anhydrous ethanol for more than three times, and then dry it in a vacuum drying oven at 60°C;

[0055] 2) The second step is to synthesize the Mo-doped VS2 precursor. The preparation method is to weigh 0.2106g of ammonium metavanadate, 0.0353g of ammonium molybdate and 2ml of ammonia water, add them to water, stir and dissolve into a transparent solution, then weigh 1.5026g of thioacetamide and add it to the above transparent solution, stir to obtain a mixed solution; then add carbon cloth as a growth substrate, pour the liquid into a polytetrafluoroethylene liner and seal it, then put the polytetrafluoroethylene liner into a stainless steel reactor and tighten it, and then place it in a 160°C oven for 24 hours. After naturally cooling to room temperature, the product is washed with anhydrous ethanol and deoxygenated deionized water in turn; then put it into a refrigerator and freeze it for 12 hours, and then place it in a freeze dryer at -50°C and vacuum dry for 30 hours to obtain a molybdenum-doped vanadium disulfide precursor material;

[0056] 3) The third step is to perform P doping by heat treatment. The preparation method is to use sodium hypophosphite as the P doping source, place 0.4g of sodium hypophosphite in a magnetic boat at the center of the upstream heating zone of a tubular furnace, and place a whole piece of the above-mentioned molybdenum-doped vanadium disulfide precursor material in the magnetic boat and place it in the center of the downstream heating zone; in an argon atmosphere, heat and raise the temperature, control the temperature of the upstream heating zone to 300°C, and the temperature of the downstream heating zone to 400°C, keep warm for 3 hours, and cool to room temperature to obtain a VS2 electrocatalytic electrode material co-doped with molybdenum cations and phosphorus anions.

[0057] X-ray diffractometer (XRD) was used to characterize the structure of the molybdenum cation and phosphorus anion co-doped VS2 electrocatalytic electrode material obtained above. Figure 1 As shown, the results show that the molybdenum cation and phosphorus anion co-doped VS2 electrocatalytic electrode material is a single vanadium disulfide phase without other impurity phases, and its 011 plane left shift is caused by P doping; the morphology of the molybdenum cation and phosphorus anion co-doped VS2 electrocatalytic electrode material was characterized by scanning electron microscopy (SEM), as shown in Figure 2 As shown in the figure, it can be seen that the molybdenum cation and phosphorus anion co-doped VS2 electrocatalytic electrode material is formed by self-assembly of nano-sheet molybdenum cation and phosphorus anion co-doped VS2 catalyst materials to form a micron-sized flower-like structure uniformly grown on a carbon cloth substrate. The above molybdenum cation and phosphorus anion co-doped VS2 catalyst material is subjected to surface scanning analysis using an energy dispersive spectrometer (EDS), as shown in FIG. Figure 3 As shown, the results show that the material contains four elements: Mo, P, V, and S, and they are evenly distributed.

[0058] The electrochemical hydrogen evolution performance of the VS2 catalyst material co-doped with molybdenum cations and phosphorus anions was tested using a three-electrode system, with a carbon rod as the counter electrode, a Hg|Hg2SO4 electrode as the reference electrode, a molybdenum cation and phosphorus anion co-doped VS2 catalyst material as the working electrode, and a 0.5 mol / L sulfuric acid solution as the electrolyte. The test instrument was a Shanghai Chenhua CHI660E electrochemical workstation. The linear sweep voltammetry curve had a linear sweep range of -1.0 to 0 V (relative to the standard hydrogen electrode), a sweep rate of 3 mV / s, and all tests were performed in a constant temperature 25°C water bath environment. The test results are shown in Figure 2. Figure 5 and Figure 6 As shown, after data processing and calculation, at 50mAcm -2 The overpotential is as low as -0.2303V (relative to standard hydrogen electrode) and the Tafel slope is as low as 49.5mV / dec at the current density. The linear scanning range of the linear cyclic voltammetry curve is between 0.15 and 0.25V (relative to standard hydrogen electrode). Figure 6As shown, it can be seen that the CV curves of all materials are rectangular in shape, indicating that no redox reaction occurs. Figure 12 The capacitance current density (Δj=j a -j b , where j a and j b The relationship between the current density and scan rate in the CV curve at 0.20 V (relative to standard hydrogen electrode) and its linear fitting function are shown. Sample C dl The value is equal to half of the slope of the straight line in the figure, and its C dl The value is 107mF cm -2 . Figure 13 The polarization curves of the sample before and after 5000 CV cycles are shown in Figure 2. Compared with the initial polarization curve, the polarization curve of the sample after 5000 CV cycles is significantly improved at 30 mA cm -2 When , its overpotential increases by only 22mV, indicating that the VS2 catalyst material co-doped with molybdenum cations and phosphorus anions has excellent hydrogen evolution stability. Figure 14 For samples at 10 mA cm -2 From the potential-time curve of the constant current polarization test for 120 h at a current density of 1.5 GHz, it can be seen that the overpotential of the sample only dropped by 4 mV after a long period of constant current polarization test, indicating that the VS2 catalyst material co-doped with molybdenum cations and phosphorus anions has excellent hydrogen evolution stability.

[0059] Example 2:

[0060] 1) First step: Carbon cloth (CC) treatment: Cut the carbon cloth into rectangular pieces of 1 cm × 1.5 cm in size, soak the carbon cloth in a mixed acid of nitric acid and sulfuric acid (3:1) for more than 12 hours, then ultrasonically wash it with deionized water and anhydrous ethanol for more than three times, and then dry it in a vacuum drying oven at 60°C;

[0061] 2) The second step is to synthesize the Mo-doped VS2 precursor. The preparation method is to weigh 0.2106g of ammonium metavanadate, 0.0353g of ammonium molybdate and 2ml of ammonia water, add them to water, stir and dissolve into a transparent solution, then weigh 1.5026g of thioacetamide and add it to the above transparent solution, stir to obtain a mixed solution; then add carbon cloth as a growth substrate, pour the liquid into a polytetrafluoroethylene liner and seal it, then put the polytetrafluoroethylene liner into a stainless steel reactor and tighten it, and then place it in a 160°C oven for 24 hours. After naturally cooling to room temperature, the product is washed with anhydrous ethanol and deoxygenated deionized water in turn; then put it into a refrigerator and freeze it for 12 hours, and then place it in a freeze dryer at -50°C and vacuum dry for 30 hours to obtain a molybdenum-doped vanadium disulfide precursor material;

[0062] 3) The third step is to perform P doping by heat treatment. The preparation method is to use sodium hypophosphite as the P doping source, place 0.4g of sodium hypophosphite in a magnetic boat at the center of the upstream heating zone of a tubular furnace, and place a whole piece of the above-mentioned molybdenum-doped vanadium disulfide precursor material in the magnetic boat and place it in the center of the downstream heating zone; in an argon atmosphere, heat and raise the temperature, control the temperature of the upstream heating zone to 300°C, the temperature of the downstream heating zone to 300°C, keep warm for 3 hours, and after cooling to room temperature, obtain a VS2 electrocatalytic electrode material co-doped with molybdenum cations and phosphorus anions.

[0063] X-ray diffractometer (XRD) was used to characterize the structure of the molybdenum cation and phosphorus anion co-doped VS2 electrocatalytic electrode material obtained above. Figure 1 As shown, the results show that the molybdenum cation and phosphorus anion co-doped VS2 electrocatalytic electrode material is a single vanadium disulfide phase without other impurity phases, and its 011 plane left shift is caused by P doping; the morphology of the above-mentioned molybdenum cation and phosphorus anion co-doped VS2 electrocatalytic electrode material was characterized by SEM. The molybdenum cation and phosphorus anion co-doped VS2 electrocatalytic electrode material is composed of nano-sheet molybdenum cation and phosphorus anion co-doped VS2 catalyst material self-assembled to form a micron-sized flower-like structure uniformly grown on a carbon cloth substrate. The above-mentioned molybdenum cation and phosphorus anion co-doped VS2 catalyst material was subjected to surface scanning analysis by EDS. The results showed that the material contains four elements: Mo, P, V, and S, and they are uniformly distributed.

[0064] The electrochemical hydrogen evolution performance of the VS2 catalyst material co-doped with molybdenum cations and phosphorus anions was tested using a three-electrode system, with a carbon rod as the counter electrode, a Hg|Hg2SO4 electrode as the reference electrode, a molybdenum cation and phosphorus anion co-doped VS2 catalyst material as the working electrode, and a 0.5 mol / L sulfuric acid solution as the electrolyte. The test instrument was a Shanghai Chenhua CHI660E electrochemical workstation. The linear sweep voltammetry curve had a linear sweep range of -1.0 to 0 V (relative to the standard hydrogen electrode), a sweep rate of 3 mV / s, and all tests were performed in a constant temperature 25°C water bath environment. The test results are shown in Figure 2. Figure 5 and Figure 6 As shown, after data processing and calculation, at 50mA cm -2 The overpotential is as low as -0.2415V (relative to standard hydrogen electrode) and the Tafel slope is as low as 54.1mV / dec at the current density. The linear scanning range of the linear cyclic voltammetry curve is between 0.15 and 0.25V (relative to standard hydrogen electrode). Figure 7 As shown, it can be seen that the CV curves of all materials are rectangular in shape, indicating that no redox reaction occurs. Figure 12 The capacitance current density (Δj=j a -j b , where j aand j b The relationship between the current density and scan rate in the CV curve at 0.20 V (relative to standard hydrogen electrode) and its linear fitting function are shown. Sample C dl The value is equal to half of the slope of the straight line in the figure, and its C dl The value is 93.6mF cm -2 .

[0065] Example 3:

[0066] 1) First step: Carbon cloth (CC) treatment: Cut the carbon cloth into rectangular pieces of 1 cm × 1.5 cm in size, soak the carbon cloth in a mixed acid of nitric acid and sulfuric acid (3:1) for more than 12 hours, then ultrasonically wash it with deionized water and anhydrous ethanol for more than three times, and then dry it in a vacuum drying oven at 60°C;

[0067] 2) The second step is to synthesize the Mo-doped VS2 precursor. The preparation method is to weigh 0.2106g of ammonium metavanadate, 0.0353g of ammonium molybdate and 2ml of ammonia water, add them to water, stir and dissolve into a transparent solution, then weigh 1.5026g of thioacetamide and add it to the above transparent solution, stir to obtain a mixed solution; then add carbon cloth as a growth substrate, pour the liquid into a polytetrafluoroethylene liner and seal it, then put the polytetrafluoroethylene liner into a stainless steel reactor and tighten it, and then place it in a 160°C oven for 24 hours. After naturally cooling to room temperature, the product is washed with anhydrous ethanol and deoxygenated deionized water in turn; then put it into a refrigerator and freeze it for 12 hours, and then place it in a freeze dryer at -50°C and vacuum dry for 30 hours to obtain a molybdenum-doped vanadium disulfide precursor material;

[0068] 3) The third step is to perform P doping by heat treatment. The preparation method is to use sodium hypophosphite as the P doping source, place 0.4g of sodium hypophosphite in a magnetic boat at the center of the upstream heating zone of a tubular furnace, and place a whole piece of the above-mentioned molybdenum-doped vanadium disulfide precursor material in the magnetic boat and place it in the center of the downstream heating zone; in an argon atmosphere, heat and raise the temperature, control the temperature of the upstream heating zone to 300°C, and the temperature of the downstream heating zone to 500°C, keep warm for 3 hours, and after cooling to room temperature, obtain a VS2 electrocatalytic electrode material co-doped with molybdenum cations and phosphorus anions.

[0069] X-ray diffractometer (XRD) was used to characterize the structure of the molybdenum cation and phosphorus anion co-doped VS2 electrocatalytic electrode material obtained above. Figure 1As shown, the results show that the molybdenum cation and phosphorus anion co-doped VS2 electrocatalytic electrode material is a single vanadium disulfide phase without other impurity phases, and its 011 plane left shift is caused by P doping; the morphology of the above-mentioned molybdenum cation and phosphorus anion co-doped VS2 electrocatalytic electrode material was characterized by SEM. The molybdenum cation and phosphorus anion co-doped VS2 electrocatalytic electrode material is composed of nano-sheet molybdenum cation and phosphorus anion co-doped VS2 catalyst material self-assembled to form a micron-sized flower-like structure uniformly grown on a carbon cloth substrate. The above-mentioned molybdenum cation and phosphorus anion co-doped VS2 catalyst material was subjected to surface scanning analysis by EDS. The results showed that the material contains four elements: Mo, P, V, and S, and they are uniformly distributed.

[0070] The electrochemical hydrogen evolution performance of the VS2 catalyst material co-doped with molybdenum cations and phosphorus anions was tested using a three-electrode system, with a carbon rod as the counter electrode, a Hg|Hg2SO4 electrode as the reference electrode, a molybdenum cation and phosphorus anion co-doped VS2 catalyst material as the working electrode, and a 0.5 mol / L sulfuric acid solution as the electrolyte. The test instrument was a Shanghai Chenhua CHI660E electrochemical workstation. The linear sweep voltammetry curve had a linear sweep range of -1.0 to 0 V (relative to the standard hydrogen electrode), a sweep rate of 3 mV / s, and all tests were performed in a constant temperature 25°C water bath environment. The test results are shown in Figure 2. Figure 5 and Figure 6 As shown, after data processing and calculation, at 50mAcm -2 The overpotential is as low as -0.2517V (relative to standard hydrogen electrode) and the Tafel slope is as low as 54.7mV / dec at the current density. The linear scanning range of the linear cyclic voltammetry curve is between 0.15 and 0.25V (relative to standard hydrogen electrode). The results are as follows Figure 8 As shown, it can be seen that the CV curves of all materials are rectangular in shape, indicating that no redox reaction occurs. Figure 12 The capacitance current density (Δj=j a -j b , where j a and j b The relationship between the current density and scan rate in the CV curve at 0.20 V (relative to standard hydrogen electrode) and its linear fitting function are shown. Sample C dl The value is equal to half of the slope of the straight line in the figure, and its C dl The value is 75.9mF cm -2 .

[0071] Comparative Example 1:

[0072] 1) First step: Carbon cloth (CC) treatment: Cut the carbon cloth into rectangular pieces of 1 cm × 1.5 cm in size, soak the carbon cloth in a mixed acid of nitric acid and sulfuric acid (3:1) for more than 12 hours, then ultrasonically wash it with deionized water and anhydrous ethanol for more than three times, and then dry it in a vacuum drying oven at 60°C;

[0073] 2) The second step is to synthesize Mo-doped VS2 material. The preparation method is to weigh 0.2106g of ammonium metavanadate, 0.0353g of ammonium molybdate and 2ml of ammonia water, add them to water, stir and dissolve into a transparent solution, then weigh 1.5026g of thioacetamide and add it to the above transparent solution, stir to obtain a mixed solution; then add carbon cloth as a growth substrate, pour the liquid into a polytetrafluoroethylene liner and seal it, then put the polytetrafluoroethylene liner into a stainless steel reactor and tighten it, and then place it in a 160°C oven for 24 hours. After naturally cooling to room temperature, the product is washed with anhydrous ethanol and deoxygenated deionized water in sequence; then it is placed in a refrigerator and frozen for 12 hours, and then placed in a freeze dryer at -50°C and vacuum dried for 30 hours to obtain molybdenum-doped vanadium disulfide material;

[0074] X-ray diffractometer (XRD) was used to characterize the structure of the Mo-doped VS2 electrocatalytic electrode material obtained above. Figure 1 As shown, the results show that the Mo-doped VS2 electrocatalytic electrode material is a single vanadium disulfide phase without the presence of other impurity phases.

[0075] The electrochemical hydrogen evolution performance of Mo-doped VS2 catalyst material was tested using a three-electrode system, with a carbon rod as the counter electrode, a Hg|Hg2SO4 electrode as the reference electrode, a molybdenum-doped vanadium disulfide material as the working electrode, and a 0.5 mol / L sulfuric acid solution as the electrolyte. The test instrument was a Shanghai Chenhua CHI660E electrochemical workstation. The linear sweep voltammetry curve had a linear sweep range of -1.0 to 0 V (relative to the standard hydrogen electrode) with a sweep rate of 3 mV / s. All tests were conducted in a constant temperature water bath at 25°C. The test results are shown in Figure 2. Figure 5 and Figure 6 As shown, after data processing and calculation, at 50mA cm -2 The overpotential is as low as -0.2694V (relative to standard hydrogen electrode) and the Tafel slope is as low as 63.3mV / dec at the current density. The linear scanning range of the linear cyclic voltammetry curve is between 0.15 and 0.25V (relative to standard hydrogen electrode). The results are as follows: Figure 9 As shown, it can be seen that the CV curves of all materials are rectangular in shape, indicating that no redox reaction occurs. Figure 12 The capacitance current density (Δj=j a -j b , where j a and j bThe relationship between the current density and scan rate in the CV curve at 0.20 V (relative to standard hydrogen electrode) and its linear fitting function are shown. Sample C dl The value is equal to half of the slope of the straight line in the figure, and its C dl The value is 62.5mF cm -2 .

[0076] Comparative Example 2:

[0077] 1) First step: Carbon cloth (CC) treatment: Cut the carbon cloth into rectangular pieces of 1 cm × 1.5 cm in size, soak the carbon cloth in a mixed acid of nitric acid and sulfuric acid (3:1) for more than 12 hours, then ultrasonically wash it with deionized water and anhydrous ethanol for more than three times, and then dry it in a vacuum drying oven at 60°C;

[0078] 2) The second step is to synthesize a pure VS2 precursor. The preparation method is to add a vanadium source and ammonia water to water, stir until transparent, then add a sulfur source and stir to obtain a mixed solution; then add carbon cloth as a growth substrate, and then perform a one-step hydrothermal reaction on the mixed solution. The reaction product is washed and dried to obtain a pure vanadium disulfide precursor material;

[0079] The preparation method is to weigh 0.2106g of ammonium metavanadate, add 2ml of ammonia water to water, stir and dissolve into a transparent solution, then weigh 1.5026g of thioacetamide and add it to the above transparent solution, stir to obtain a mixed solution; then add carbon cloth as a growth substrate, pour the liquid into a polytetrafluoroethylene liner and seal it, then put the polytetrafluoroethylene liner into a stainless steel reactor and tighten it, and then place it in a 160°C oven for 24 hours. After naturally cooling to room temperature, the product is washed with anhydrous ethanol and deoxygenated deionized water in sequence; then placed in a refrigerator and frozen for 12 hours, and then placed in a freeze dryer at -50°C and vacuum dried for 30 hours to obtain pure vanadium disulfide precursor material;

[0080] 3) The third step is to perform P doping by heat treatment. The preparation method is to use sodium hypophosphite as the P doping source, place 0.4g of sodium hypophosphite in a magnetic boat at the center of the upstream heating zone of a tubular furnace, and place the above-mentioned whole piece of pure vanadium disulfide precursor material in the magnetic boat and place it in the center of the downstream heating zone; in an argon atmosphere, heat and raise the temperature, control the temperature of the upstream heating zone to 300°C, and the temperature of the downstream heating zone to 400°C, keep warm for 3 hours, and cool to room temperature to obtain a P-doped VS2 electrocatalytic electrode material.

[0081] X-ray diffractometer (XRD) was used to characterize the structure of the P-doped VS2 electrocatalytic electrode material obtained above. Figure 1 As shown, the results show that the VS2 electrocatalytic electrode material co-doped with molybdenum cations and phosphorus anions is a single vanadium disulfide phase without other impurity phases, and its 011 plane left shift is caused by P doping.

[0082] The electrochemical hydrogen evolution performance of the P-doped VS2 electrocatalytic electrode material was tested using a three-electrode system, with a carbon rod as the counter electrode, a Hg|Hg2SO4 electrode as the reference electrode, a P-doped VS2 electrocatalytic electrode material as the working electrode, and a 0.5 mol / L sulfuric acid solution as the electrolyte. The test instrument was a Shanghai Chenhua CHI660E electrochemical workstation. The linear sweep voltammetry curve had a linear sweep range of -1.0 to 0 V (relative to the standard hydrogen electrode) with a sweep rate of 3 mV / s. All tests were performed in a constant temperature water bath at 25°C. The test results are shown in Figure 2. Figure 5 and Figure 6 As shown, after data processing and calculation, at 50mAcm -2 The overpotential is as low as -0.2743V (relative to standard hydrogen electrode) and the Tafel slope is as low as 64.6mV / dec at the current density. The linear scanning range of the linear cyclic voltammetry curve is between 0.15 and 0.25V (relative to standard hydrogen electrode). Figure 10 As shown, it can be seen that the CV curves of all materials are rectangular in shape, indicating that no redox reaction occurs. Figure 12 The capacitance current density (Δj=j a -j b , where j a and j b The relationship between the current density and scan rate in the CV curve at 0.20 V (relative to standard hydrogen electrode) and its linear fitting function are shown. Sample C dl The value is equal to half of the slope of the straight line in the figure, and its C dl The value is 60.3mFcm -2 .

[0083] Comparative Example 3:

[0084] 1) First step: Carbon cloth (CC) treatment: Cut the carbon cloth into rectangular pieces of 1 cm × 1.5 cm in size, soak the carbon cloth in a mixed acid of nitric acid and sulfuric acid (3:1) for more than 12 hours, then ultrasonically wash it with deionized water and anhydrous ethanol for more than three times, and then dry it in a vacuum drying oven at 60°C;

[0085] 2) The second step is to synthesize pure vanadium disulfide material. The preparation method is to add a vanadium source and ammonia water to water, stir until transparent, then add a sulfur source and stir to obtain a mixed solution; then add carbon cloth as a growth substrate, and then perform a one-step hydrothermal reaction on the mixed solution. The reaction product is washed and dried to obtain pure vanadium disulfide material;

[0086] X-ray diffractometer (XRD) was used to characterize the structure of the pure vanadium disulfide material obtained above. Figure 1As shown, the results show that the pure vanadium disulfide material is a single vanadium disulfide phase without the presence of other impurity phases; the morphology of the above pure vanadium disulfide material was characterized by SEM, as shown Figure 15 As shown in the figure, it can be seen that the pure vanadium disulfide material is self-assembled by nano-sheet pure vanadium disulfide material to form a micron-sized flower-like structure uniformly grown on the carbon cloth substrate. The above pure vanadium disulfide material is subjected to surface scanning analysis using EDS, as shown in FIG. Figure 16 As shown, the results show that the material contains three elements, V and S, and they are evenly distributed.

[0087] The electrochemical hydrogen evolution performance of pure vanadium disulfide material was tested using a three-electrode system, with a carbon rod as the counter electrode, a Hg|Hg2SO4 electrode as the reference electrode, pure vanadium disulfide material as the working electrode, and a 0.5 mol / L sulfuric acid solution as the electrolyte. The test instrument was a Shanghai Chenhua CHI660E electrochemical workstation. The linear sweep voltammetry curve had a linear sweep range of -1.0 to 0 V (relative to the standard hydrogen electrode) with a sweep rate of 3 mV / s. All tests were conducted in a constant temperature water bath at 25°C. The test results are shown in Figure 2. Figure 5 and Figure 6 As shown, after data processing and calculation, at 50mA cm -2 The overpotential is as low as -0.5514V (relative to standard hydrogen electrode) at this current density, and the Tafel slope is 209.7mV / dec. The linear cyclic voltammetry curve has a linear sweep range of 0.15 to 0.25V (relative to standard hydrogen electrode), and the results are as follows: Figure 11 As shown, it can be seen that the CV curves of all materials are rectangular in shape, indicating that no redox reaction occurs. Figure 12 The capacitance current density (Δj=j a -j b , where j a and j b The relationship between the current density and scan rate in the CV curve at 0.20 V (relative to standard hydrogen electrode) and its linear fitting function are shown. Sample C dl The value is equal to half of the slope of the straight line in the figure, and its C dl The value is 3.0mF cm -2 .

[0088] The above description is only a partial embodiment of the present invention and does not limit the present invention in any form. Any simple modification, change and modification made to the above embodiment based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A VS2 catalytic material co-doped with molybdenum cations and phosphorus anions, characterized by: The micron flowers are uniformly grown on a carbon-based material; the micron flowers are assembled from VS2 nanosheets co-doped with molybdenum cations and phosphorus anions.

2. The VS2 catalytic material co-doped with molybdenum cations and phosphorus anions according to claim 1, characterized in that: In the co-doped VS2 of molybdenum cations and phosphorus anions, the doping amount of molybdenum cations is measured by the atomic ratio of Mo to V of (0.05~0.15): (0.95~0.85), and the doping amount of phosphorus anions is measured by the atomic ratio of P to S of (0.01~0.15): (0.99~0.85).

3. A VS2 catalytic material co-doped with molybdenum cations and phosphorus anions according to claim 1 or 2, characterized in that: The microflowers grow into a layered structure.

4. The VS2 catalytic material co-doped with molybdenum cations and phosphorus anions according to claim 1, characterized in that: The carbon-based material is carbon cloth.

5. The method for preparing a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) performing oxidation pretreatment on the surface of the carbon-based material to obtain a pretreated carbon-based material; 2) adding a molybdenum source, a vanadium source, and aqueous ammonia to water, stirring until transparent, and then adding a sulfur source and stirring to obtain a mixed solution; The mixed solution is transferred into a reactor containing a pretreated carbon-based material to undergo a hydrothermal reaction to obtain a molybdenum-doped vanadium disulfide material; 3) Using sodium hypophosphite as a phosphorus source, phosphorus-doping the molybdenum-doped vanadium disulfide material is performed through a heat treatment method to obtain the obtained product.

6. The method for preparing a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions according to claim 5, characterized in that: The oxidation pretreatment process is as follows: the carbon-based material is soaked in a mixed acid of nitric acid and sulfuric acid.

7. The method for preparing a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions according to claim 5, characterized in that: The molybdenum source includes at least one of ammonium molybdate, sodium molybdate and potassium molybdate; The vanadium source includes ammonium metavanadate and / or sodium vanadate; The sulfur source includes thiourea and / or thioacetamide; The molybdenum source, vanadium source and sulfur source are measured according to the atomic ratio of molybdenum, vanadium and sulfur of (0.05-0.15): (0.95-0.85): (5-10); the mass ratio of the phosphorus source to the molybdenum-doped vanadium disulfide material is 1.2-1.7:

1.

8. The method for preparing a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions according to claim 5, characterized in that: The conditions of the hydrothermal reaction are: temperature of 140-220° C. and time of 12-26 hours.

9. The method for preparing a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions according to claim 5, characterized in that: The process of phosphorus doping of molybdenum-doped vanadium disulfide material by heat treatment is as follows: sodium hypophosphite is placed in the upstream heating zone of a tubular furnace, and the molybdenum-doped vanadium disulfide material is placed in the downstream heating zone of the tubular furnace. An inert atmosphere is filled into the tubular furnace, and the temperature of the upstream heating zone is controlled at 300-350°C, and the temperature of the downstream heating zone is controlled at 300-500°C. After keeping warm for 2-4 hours, the mixture is cooled to room temperature.

10. Use of a VS2 catalytic material co-doped with molybdenum cations and phosphorus anions according to any one of claims 1 to 3, characterized in that: Applied to electrocatalytic hydrogen evolution reaction.

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