Amorphous / crystalline RuO2 / WO X -SO4 2- Composite materials, PEM electrolyzer devices, and their preparation and use in the electrolysis of water to produce hydrogen

Abstract

The application belongs to the field of water electrolysis, and particularly relates to amorphous / crystal RuO2 / WO x -SO4 2‑ The application relates to a composite material, a PEM water electrolysis device, preparation of the device and application of the device in hydrogen production by water electrolysis, wherein the amorphous / crystal RuO2 / WO x -SO4 2‑ The composite material comprises multivalent WO x and amorphous / crystal RuO2; and SO4 2‑ modified and anchored on the amorphous / crystal RuO2; the multivalent WO x is an oxide of tungsten with positive tetravalence, positive pentavalence and positive hexavalence; and the amorphous / crystal RuO2 comprises a core of rutile-phase RuO2 and amorphous RuO2 coated on the surface of the core. The application provides a material with a special physicochemical structure, which can unexpectedly meet the requirements of acidic OER catalysis based on the joint control of composition and physicochemical structure, and can obtain excellent catalytic activity and stability and optimize the utilization rate of noble metal Ru.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrocatalytic materials, in particular to the field of OER catalytic materials. BACKGROUND

[0002] With the promotion of the global "double carbon" target, green hydrogen as a zero-carbon energy carrier has attracted much attention. Proton exchange membrane (PEM) water electrolysis technology has become a core technology path for the large-scale production of "green hydrogen" due to its advantages such as fast start-up speed, high gas purity, and adaptability to fluctuating renewable energy sources. The anode reaction of PEM water electrolysis is the oxygen evolution reaction (OER) under acidic conditions. This reaction involves a four-electron transfer process, which is kinetically slow and requires a highly efficient catalyst to reduce the overpotential. At the same time, the acidic environment and high oxidation potential can cause corrosion phenomena such as dissolution and oxidation of the catalyst, severely affecting the life of the electrolytic cell, thus imposing stricter requirements on OER catalysts. Currently, acid-resistant OER catalysts mainly rely on noble metal-based materials, among which ruthenium (Ru)-based catalysts are considered the most promising candidate due to their suitable electronic structure and high resistance to corrosion and oxidation. However, traditional Ru-based catalysts (such as RuO2) have the following problems, for example:

[0003] 1. Poor stability: Ru is easily oxidized to volatile RuO4 under acidic high potential, leading to continuous dissolution of the catalyst, with a typical life of <500 hours;

[0004] 2. Insufficient activity: Commercial RuO2 has an overpotential of >250 mV at a current density of 10 mA / cm 2 , which is much higher than the industrial application requirement (<200 mV).

[0005] 3. Complex process: Existing bimetallic catalyst preparation relies on vacuum equipment (such as ALD), making it difficult to mass-produce.

[0006] To solve the above problems, researchers have developed various improvement strategies, for example:

[0007] 1. Element doping: Introducing transition metals such as W and Mo to adjust the Ru-O bond strength through electronic effects. For example, the Chinese patent document with publication number CN118026300A discloses a preparation method for a rhodium-ruthenium binary metal oxide used in the anode of a PEM electrolytic cell. Specifically, rhodium-ruthenium binary metal oxide nanoparticles are constructed from the bottom up by an impregnation reduction method. The introduction of a structural aid, carbon black, allows the element precursors to maintain uniform particle size during the high-temperature reduction step. By introducing an electronic aid, Rh, and the main element, Ru, to form a binary metal oxide, the electronic structure of the Ru species is optimized, and the crystal lattice of the nanoparticles is stabilized.

[0008] 2. Structure regulation: Designing nanowires, porous structures to increase specific surface area. For example, the Chinese patent document with publication number CN118127561A discloses a rare earth element doped RuO2 material and its preparation method and application. The rare earth element doped RuO2 material has a rutile crystal structure, wherein rare earth atoms occupy Ru atom sites of rutile RuO2 and are distributed in the crystal structure of the material.

[0009] 3. Interface engineering: Building heterojunctions. For example, the Chinese patent document with publication number CN116356361A discloses a preparation method of amorphous IrO x / Ru catalyst for PEM electrolytic water hydrogen production, which comprises: ultrasonic treatment of metal ruthenium powder, iridium salt, isopropyl alcohol, stirring to form a solid suspension, adding sodium nitrate powder and mixing uniformly; constant temperature heating in a water bath, stirring until the liquid is evaporated, to obtain a brown yellow powder; calcining at 350-450℃, adding perchloric acid solution after natural cooling and ultrasonic treatment, centrifugal separation to obtain black solid; after centrifugal washing and drying treatment, amorphous IrO x / Ru catalyst is obtained.

[0010] In summary, although the existing technology provides some Ru-based OER materials, and these materials can also obtain good OER performance under acidic conditions, the existing preparation process has problems such as complex operation, high cost, and difficult to mass production, which restricts the industrial application of Ru-based catalysts. Therefore, developing a Ru-based catalyst with high activity, high stability and mass production has become the key to the breakthrough of PEM electrolytic water technology. SUMMARY

[0011] In view of the problems of unsatisfactory OER catalytic activity and stability of existing Ru-based catalysts under acidic conditions, the first object of the present application is to provide an amorphous / crystal RuO2 / WO x -SO4 2- composite material, aiming to provide an electrocatalytic material with high activity and high stability suitable for acidic OER catalysis.

[0012] The second object of the present application is to provide a preparation method of the amorphous / crystal RuO2 / WO x -SO4 2- composite material.

[0013] The third object of the present application is to provide an application of the amorphous / crystal RuO2 / WO x -SO4 2- composite material in PEM electrolytic water hydrogen production.

[0014] The fourth object of the present application is to provide a PEM electrolytic water hydrogen production system comprising the amorphous / crystal RuO2 / WOx -SO4 2- PEM electrolyzer device of composite material.

[0015] The existing Ru-based catalyst has poor stability at an acidic high potential, Ru is oxidized into volatile RuO4, which causes continuous loss of the catalyst due to dissolution, in addition, the content of noble metal of the existing catalyst material is still high and the preparation process is complex. In view of the problem, the present application provides the following technical scheme after in-depth research:

[0016] Amorphous / crystalline RuO2 / WO x -SO4 2- Composite material, comprising multivalent WO x (also referred to as multivalent tungsten oxide) and amorphous / crystalline RuO2; and SO4 2- ;

[0017] The multivalent WO x is an oxide of tungsten with a valence of +4, +5 or +6; the amorphous / crystalline RuO2 comprises a core of rutile phase RuO2, and an amorphous RuO2 coating on the surface of the core.

[0018] The present application innovatively provides a material with a special physicochemical structure, which can unexpectedly meet the requirements of acidic OER catalysis based on the joint control of composition and physicochemical structure, and can improve the catalytic activity, stability and Ru utilization rate.

[0019] The multivalent WO x and the amorphous / crystalline RuO2 have a molar ratio of Ru / W of 0.8-2.5:1.

[0020] The mass percentage of SO4 2- is 5-12%.

[0021] The amorphous / crystalline RuO2 has a "core-shell" structure: the core is rutile phase RuO2, which accounts for 60-80% of the total mass of the amorphous / crystalline RuO2; the overall particle size is 3-8 nm.

[0022] Amorphous / crystalline RuO2 / WO x -SO4 2- The composite material is a three-dimensional porous network material with a pore size distribution of 20-50 nm, a specific surface area of ≥100 m 2 / g, and an average particle size of 8-15 nm.

[0023] The present application also provides a preparation method of the amorphous / crystalline RuO2 / WO x -SO4 2- composite material, comprising the following steps:

[0024] Step 1:

[0025] Solution A containing a compound of formula 1, a W source, an auxiliary agent, an acid, and a solvent a is subjected to a first-stage solvothermal reaction to obtain WS2 nanosheets;

[0026] Formula 1

[0027] In formula 1, R1 is a C1-C6 alkyl group;

[0028] The pH of solution A is 1.0-3.5;

[0029] The auxiliary agent is at least one of sodium hypophosphite, potassium hypophosphite, ammonium hypophosphite, and sodium phosphite;

[0030] Step 2:

[0031] Solution B containing the WS2 nanosheets prepared in step 1, a base, a Ru source, and a solvent b is subjected to a second-stage solvothermal reaction to coat the WS2 surface with a Ru hydroxide colloid;

[0032] Step 3:

[0033] The product of step 2 is calcined at 350-450 DEG C to obtain the amorphous / crystal RuO2 / WO x -SO4 2- composite material.

[0034] The present application innovatively shows that the use of a compound of formula 1 with a special structure and an auxiliary agent at the pH in the first-stage solvothermal reaction can prepare WS2 nanosheets with a special physicochemical structure. The WS2 nanosheets are further used as a precursor in the second-stage solvothermal reaction with the assistance of a base to composite a Ru hydroxide colloid on the surface, and the product is further calcined at a subsequent temperature, so that a multi-valence WO x is constructed in situ, and the amorphous / crystal RuO2 is in-situ targeted modified with SO4 2- The present application shows that the preparation method can in-situ and synchronously construct the material with the physicochemical structure, and the material unexpectedly has excellent acid resistance, excellent OER catalytic activity, and long cycle stability.

[0035] In the present application, solution A containing a compound of formula 1, a W source, an auxiliary agent, an acid, and a solvent a is mixed to obtain, and subjected to a first-stage solvothermal reaction under certain conditions. After cooling to room temperature, the product is washed, dried, and the like to obtain WS2 nanosheets.

[0036] In the present application, the special control of the sulfur source can construct WS2 nanosheets with special physicochemical structures, the material prepared by the preparation method can unexpectedly adapt to the subsequent Ru conversion, and the variable valence WO x , and SO4 2- modified amorphous / crystal RuO2 material, thereby improving the acidic OER activity and stability of the prepared material.

[0037] In the present application, the W source is a water-soluble salt containing WO4 2- ion; preferably at least one of sodium tungstate and ammonium tungstate.

[0038] In the present application, the solvent a in solution A is an aqueous solvent, preferably water or a mixed solvent of water and a water-soluble organic solvent.

[0039] The capacity of solvent a can be reasonably adjusted as needed, for example, the concentration of formula 1 in solution A is controlled to be 0.01-0.03 g / mL.

[0040] In the present application, the molar ratio of formula 1 compound, W source, and auxiliary agent can be reasonably adjusted as needed, for example, it can be 5:0.5-2:0.5-3; preferably 5:1-1.5:1-2.5.

[0041] In the present application, the acid can be a mineral acid, for example, hydrochloric acid.

[0042] In the present application, the pH of the first stage of the solvothermal reaction can be 1-3, for example, it can be 1, 1.5, 2, 2.5 or 3.

[0043] In the present application, the temperature of the first stage of the solvothermal reaction is 150-220℃, and further can be 180-200℃.

[0044] Preferably, the first stage of the solvothermal reaction time is 15-30 h, preferably 18-24 h.

[0045] In the present application, the washing process uses deionized water and ethanol each for two times to remove unreacted sodium salt and organic impurities.

[0046] In the present application, the drying process is carried out in an inert atmosphere. The drying temperature is, for example, 70-90℃; the drying time is, for example, 10-14 h.

[0047] The WS2 nanosheets obtained in step 1, a base, a Ru source, and a solvent b are mixed to obtain solution B, and a second stage of the solvothermal reaction is carried out under certain conditions, and the product is centrifuged, washed, and dried to obtain a black powder (WS2 nanosheets coated with Ru hydroxide colloid).

[0048] In the present application, the Ru source is Ru 3+Water-soluble salts of ions; preferably at least one of ruthenium trichloride, ruthenium nitrate.

[0049] In the present application, the molar ratio of Ru / W is 0.8-2.5:1; further can be 1-2:1; more further can be 1.4-1.6:1.

[0050] The solvent b can be an aqueous solvent; it can be water, or a mixed solvent of water and a water-soluble organic solvent. The organic solvent is, for example, an organic solvent miscible with water, such as alcohol, acetone, tetrahydrofuran, etc.

[0051] In solution B, the concentration of Ru is not particularly required, and can be reasonably controlled according to conventional principles, for example, can be 0.1-0.5 mM.

[0052] In the present application, the base can be an alkali metal hydroxide; preferably at least one of sodium hydroxide, potassium hydroxide, is used to provide an alkaline environment, adjust the pH of solution B to 9-10, and promote the Ru 3+ hydrolysis to Ru(OH)3colloid, which is adsorbed on the surface of the negatively charged WS2nanosheet by electrostatic interaction.

[0053] In the present application, the temperature of the second-stage solvothermal reaction is 100-200℃; further can be 110-140℃.

[0054] Preferably, the second-stage solvothermal reaction time is 4-8 h.

[0055] The black powder obtained in step 2 is subjected to calcination treatment under certain conditions to obtain amorphous / crystal RuO2 / WO x -SO4 2- composite material.

[0056] In the present application, the calcination treatment is carried out in an oxygen-containing atmosphere; the oxygen-containing atmosphere can be any atmosphere containing oxygen, and considering the convenience of treatment, it further can be air.

[0057] Preferably, the calcination temperature is 390-410℃.

[0058] Preferably, the calcination time is 1-5 h; further can be 1-4 h, more further can be 1.5-2.5 h.

[0059] Preferably, the calcination process is carried out under microwave assistance. The present application research shows that the calcination treatment is carried out under microwave assistance, which is helpful to further induce the preparation of the special material of amorphous / crystal RuO2 x , anchoring SO4 2- , and the material has better acidic OER activity and stability.

[0060] In the present application, the microwave-assisted power is not particularly required, for example, it can be 200-1000W, further it can be 500-800W.

[0061] Preferably, the pressure of the calcination process is 0.2-0.4MPa. The pressurization mode is pressurization by using the oxygen-containing atmosphere.

[0062] The present application research also shows that, under the preferred positive pressure, calcination helps to further induce the preparation of the multi-valent WO x , anchoring SO4 2- amorphous / crystalline RuO2 material with special physicochemical structure, and the material has more excellent acidic OER activity and stability.

[0063] The present application also provides a kind of amorphous / crystalline RuO2 / WO x -SO4 2- Composite material, which is used as OER catalytic material.

[0064] For example, the application of the present application can use amorphous / crystalline RuO2 / WO x -SO4 2- Composite material as OER catalytic material in acidic system.

[0065] The application of the present application can use amorphous / crystalline RuO2 / WO x -SO4 2- Composite material for the preparation of proton exchange membrane water electrolysis hydrogen production.

[0066] The application of the present application can use amorphous / crystalline RuO2 / WO x -SO4 2- Composite material as OER catalytic material for the preparation of water electrolysis hydrogen production of PEM water electrolysis device.

[0067] The present application also provides a PEM water electrolysis hydrogen production device, which comprises the amorphous / crystalline RuO2 / WO x -SO4 2- Composite material of the present application, or is prepared by the amorphous / crystalline RuO2 / WO x -SO4 2- Composite material.

[0068] In the present application, based on conventional ideas and means, the amorphous / crystalline RuO2 / WO x -SO4 2- Composite material of the present application can be prepared into the required OER catalytic device.

[0069] Advantages

[0070] This invention provides a novel amorphous / crystalline RuO2 / WO x -SO4 2- Composite materials, based on the synergistic combination of components and structure, can improve acid resistance and enhance their catalytic activity and stability in acidic systems.

[0071] The present invention also provides the aforementioned amorphous / crystalline RuO2 / WO x -SO4 2- The method for preparing composite materials, based on a unique two-stage solvothermal process combined with calcination, facilitates the construction of materials with special physicochemical structures and excellent acid resistance, OER catalytic activity, and stability. Furthermore, this preparation method is simple, easy to implement, and conducive to industrial-scale production.

[0072] This invention also demonstrates that the innovative use of microwave-assisted calcination and / or positive pressure calcination helps to further induce the preparation of the multivalent WO3. x Anchoring SO4 2- This material has a special physicochemical structure of amorphous / crystalline RuO2, and it has better acidic OER activity and stability. Attached Figure Description

[0073] Figure 1 The amorphous / crystalline RuO2 / WO prepared in Example 1 x -SO4 2- TEM image of the composite material.

[0074] Figure 2 The amorphous / crystalline RuO2 / WO prepared in Example 1 x -SO4 2- HRTEM image of the composite material.

[0075] Figure 3 The amorphous / crystalline RuO2 / WO prepared in Example 1 x -SO4 2- Comparison of LSV polarization curves of composite material (labeled RWS) and commercial RuO2 in OER electrochemical tests.

[0076] Figure 4 The amorphous / crystalline RuO2 / WO prepared in Example 1 x -SO4 2- The composite material was tested at 0.2 A / cm in the PEM water electrolysis device. 2 Stability test curves under current density.

[0077] Figure 5 The amorphous / crystalline RuO2 / WO prepared in Example 1 x -SO4 2-Polarization curve of the composite on a PEM device.

[0078] Figure 6 Amorphous / crystalline RuO2 / WO4 composite prepared for Example 1 x -SO4 2- XRD diffraction pattern of the composite.

[0079] Figure 7 Amorphous / crystalline RuO2 / WO4 composite prepared for Example 1 x -SO4 2- Comparison of Raman spectra of the composite and commercial RuO2. DETAILED DESCRIPTION

[0080] The following specific examples are intended to further illustrate the present content, but not further limit the scope of protection of the present application.

[0081] The reagents involved in the following examples are commercially available products directly from the market, if not otherwise specified.

[0082] Example 1

[0083] Step 1, preparation of WS2 nanosheets:

[0084] Take 0.467 g of formula 1A (formula 1 with R1 being methyl), sodium tungstate, and auxiliary agent (sodium hypophosphite), wherein the molar ratio of formula 1A, sodium tungstate, and sodium hypophosphite is 5:1:1, and sequentially add the three reagents into a beaker, pour into 30 mL of deionized water, and place on a magnetic stirrer for stirring for 30 minutes until the solid is completely dissolved to obtain a uniform transparent solution; then accurately take hydrochloric acid with a pipette, slowly drop it into the above solution, adjust the pH to 1.5-2.0, and continue to stir for 15 minutes with a magnetic stirrer to fully mix the solution; transfer the mixed solution to a 50 mL polytetrafluoroethylene-lined first-stage solvent thermal reaction kettle, seal it, and place it in an oven, set the temperature to 200±5℃, and heat for 24 hours. After the reaction is completed, take out the reaction kettle and cool it to room temperature naturally, pour out the product, wash it with deionized water twice, and then wash it with anhydrous ethanol twice to remove residual impurities, and finally place the product in a nitrogen-protected vacuum drying box and dry it at 80℃ for 12 hours to obtain WS2 nanosheets.

[0085] Step 2, ruthenium loading reaction:

[0086] Take 25 mg of the WS2 nanosheets prepared above, add it and NaOH into a beaker containing 0.2 mmol / L RuCl3 solution, control the molar ratio of Ru to W to be 1.5:1, and pH to be 9-10, first place it in an ultrasonic cleaner for ultrasonic dispersion for 20 minutes, so that the solid particles are fully dispersed, then transfer it to a magnetic stirrer for stirring for 10 minutes to obtain a uniform suspension; transfer the suspension into a 50 mL second-stage solvothermal reactor, seal it and place it in an oven, set the temperature to be 120±5℃, and keep it for 6 hours of reaction. After the reaction is completed, cool it to room temperature, centrifuge the product at 8000 rpm for 5 minutes, wash it repeatedly with deionized water until the filtrate is neutral, then wash it once with anhydrous ethanol, and then place it in a blast drying oven for drying at 80℃ for 8 hours to obtain a ruthenium-loaded composite black powder.

[0087] Step 3, calcination treatment:

[0088] Place the ruthenium-loaded composite black powder prepared in step 2 in a ceramic boat and place it in a tube furnace, introduce air as the reaction atmosphere, and adjust the gas flow to be 20 mL / min; set the tube furnace program: increase the temperature from room temperature to 400℃ at a rate of 5℃ / min, keep the target temperature for 2 hours for calcination treatment; after the calcination is completed, turn off the heating device, keep the air flowing, and let the sample cool to room temperature naturally with the furnace to finally obtain amorphous / crystalline RuO2 / WO x -SO4 2- composite material (also referred to as a catalyst or marked as RuO2 / WO x -SO4 2- or RWS).

[0089] Electrochemical test:

[0090] Take 2 mg of the prepared catalyst, disperse it in a mixture of 280 μL of ethanol, 200 μL of distilled water, and 5 wt% Nafion solution (the weight ratio of catalyst to Nafion is 2:1), and ultrasonically oscillate for 30 minutes to form a uniform suspension; then take 50 μL of the suspension, drop it on the surface of carbon paper, and naturally dry it, and then test its performance using an electrochemical workstation. The test system uses a saturated calomel electrode as the reference electrode, a platinum sheet as the counter electrode, and 0.5 M H2SO4 as the electrolyte, measures the acid catalytic activity in the range of 1.30-1.60 V vs. RHE at a scan rate of 5 mV / s; the stability test is continuously monitored at a current density of 100 mA / cm 2 .

[0091] PEM polarization test: 20 mg of prepared catalyst was weighed and dispersed in 3 mL of deionized water for 30 minutes of ultrasonic dispersion. After 25 minutes of ball milling, 5 wt% Nafion solution (catalyst, Nafion weight ratio of 4:1) and 1 mL of isopropyl alcohol were added, and the slurry was prepared again for 30 minutes of ultrasonic dispersion. The slurry was sprayed on the opposite side of the commercial Pt / C electrolytic electrode (purchased from Shengernuo, as the cathode) by means of a spray gun to prepare a RuO2 / WO x -SO4 2- (anode) || Pt / C (cathode) membrane electrode. The membrane electrode was assembled into a PEM water electrolyzer (also marked as RWS || Pt / C, active area 1 cm 2 ), the test temperature was set to 60°C, and the performance evaluation was carried out: the cell voltage curve (polarization test) in the range of 0~2.0 A / cm 2 current density was tested by linear scanning; the stability test was continuously monitored for 100 hours at 0.2 A / cm 2 current density by chronopotentiometry.

[0092] Example 2

[0093] Compared with Example 1, the only difference is that in step 2, the amount of Ru is changed, and the molar ratio of Ru to W is controlled to be 2:1, and other operations and parameters are the same as in Example 1.

[0094] Example 3

[0095] Compared with Example 1, the only difference is that in step 2, the amount of Ru is changed, and the molar ratio of Ru to W is controlled to be 1:1, and other operations and parameters are the same as in Example 1.

[0096] Example 4

[0097] Compared with Example 1, the only difference is that the preparation parameters of WS2 nanosheets in step 1 are changed, and the experimental groups are as follows:

[0098] Example 4A: Formula 1A is replaced by an equal amount of Formula 1B (Formula 1 with R1 being ethyl);

[0099] Example 4B: In step 1, the molar ratio of Formula 1A, sodium tungstate, and sodium hypophosphite is 5:1.5:2.5, the solution pH is adjusted to 2.5~3.0, the hydrothermal temperature is adjusted to 180°C, and the hydrothermal time is shortened to 18 h;

[0100] Other operations and parameters are the same as in Example 1.

[0101] Example 5

[0102] Compared with Example 1, the only difference is that the calcination process in step 3 is changed, and the specific groups are as follows:

[0103] Example 5A: the calcination temperature is lowered to 350°C, and the holding time is 2 h;

[0104] Example 5B: the calcination temperature is raised to 450°C, and the holding time is extended to 4 h;

[0105] Other operations and parameters are the same as in Example 1.

[0106] Example 6

[0107] Compared with Example 1, the only difference is that in Step 3, the calcination process is carried out under microwave assistance, wherein the power of the microwave is 600±50 W; other operations and parameters are the same as in Example 1.

[0108] Example 7

[0109] Compared with Example 1, the only difference is that in Step 3, air is used to pressurize the reaction furnace so as to calcine under positive pressure, wherein the positive pressure is 0.2~0.3 MPa (pressure fluctuation ±0.02 MPa), and other operations and parameters are the same as in Example 1.

[0110] Comparative Example 1

[0111] Compared with Example 1, the only difference is that in Step 2, no WS2 nanosheet is added, and the molar amount of RuCl3 is increased so that the molar amount of Ru is equal to the total molar amount of Ru+W in Example 1, and other operations and parameters are the same as in Example 1, and the material prepared is marked as RuO2.

[0112] Comparative Example 2

[0113] Compared with Example 1, the only difference is that in Step 1, no Formula 1A is added, and other operations and parameters are the same as in Example 1.

[0114] Comparative Example 3

[0115] Compared with Example 1, the only difference is that in Step 1, the pH adjustment of the raw material solution is 4.0, and other operations and parameters are the same as in Example 1.

[0116] Comparative Example 4

[0117] Compared with Example 1, the only difference is that in Step 1, an equimolar amount of sodium sulfite is used to replace sodium hypophosphite, and other operations and parameters are the same as in Example 1.

[0118] Comparative Example 5

[0119] Compared with Example 1, the only difference is that step 2 is not performed, but the raw materials of step 2 are directly involved in the treatment of step 3, and the difference in step 3 is that WS2 nanosheets, RuCl3 solution and NaOH are directly mixed and then calcined, and other operations and parameters are the same as in Example 1.

[0120] Comparative Example 6

[0121] Compared with Example 1, the only difference is that in step 1, thiourea is used instead of formula 1A, and other operations and parameters are the same as in Example 1.

[0122] Comparative Example 7

[0123] Compared with Example 1, the only difference is that in step 2, NaOH is not added, and other operations and parameters are the same as in Example 1.

[0124] Comparative Example 8

[0125] Compared with Example 1, the only difference is that in step 2, equimolar WO3 is used instead of WS2 nanosheets, and other operations and parameters are the same as in Example 1.

[0126] Comparative Example 9

[0127] Compared with Example 1, the only difference is that in step 3, the calcination temperature is controlled at 500°C, and the holding time is 2 h, and other operations and parameters are the same as in Example 1.

[0128] The electrochemical test results and subsequent calculation results of the catalysts prepared in each example and each comparative example and the commercial RuO2 are listed in Table 1.

[0129]

[0130] Examples 1, 2 and 3 investigated the RuO2 / WO x -SO4 2- catalysts prepared by using different Ru and W molar ratios and corresponding Ru loadings and their acidic OER performance. The Ru loading of Example 1 is 35.2%, and the overpotential is 192 mV at 10 mA / cm 2 , 295 mV at 100 mA / cm 2 , and the 100-hour decay rate is 7.2%, and the comprehensive performance is excellent. The mass activity (calculated by overpotential and loading) is 2.1 times that of commercial RuO2 (75.8 wt% Ru). It can be seen that although the Ru loading of Example 1 is only 35.2% (much lower than pure RuO2), but through the synergistic effect of Ru-W-S and SO4 2-The activity of the unit Ru is significantly improved, which shows that the application realizes high activity while reducing the amount of Ru by optimizing the loading amount and component ratio. In addition, the 100-hour attenuation rate is only 7.2%, which is much better than that of the commercial RuO2, and the high stability benefits from the appropriate loading amount of 35.2% WO x The protection of Ru is fully exerted, and the synergistic effect of Ru-O-W bond and SO4 2- Inhibits the dissolution of Ru.

[0131] As can be seen from Example 1, Example 4 and Example 5, the process described in the application can construct the material with the special physicochemical characteristics, and good acidic OER activity and stability can be obtained.

[0132] As can be seen from Example 1, Example 6 and Example 7, the microwave-assisted calcination and / or positive pressure calcination are innovatively used, which helps to further induce the preparation of the material with the special physicochemical structure of the multi-valence WO x , and the material has better acidic OER activity and stability. 2-

[0133] By comparing Example 1 with Comparative Example 1, the Ru loading amount of Comparative Example 1 is as high as 45.2% (much higher than 35.2% of Example 1), and because sodium tungstate is not added (no W phase), the 100 mA / cm 2 overpotential is increased to 390 mV, and the 100-hour attenuation rate is 45.3%. Characterization shows that under high loading, Ru lacks the protection of the W phase, and is quickly dissolved under acidic high potential, which proves that simply increasing the Ru loading amount cannot make up for the defects of the component loss, and the stabilizing effect of the W phase is indispensable. x

[0134] By comparing Example 1 with Comparative Example 2, the Ru loading amount of Comparative Example 2 is 34.8% (close to Example 1), but because formula 1A is not added, it cannot mediate the generation of WS2 nanosheets, and the final product is mainly a mixture of RuO2 and WO3, which cannot construct the variable valence tungsten oxide and the amorphous-crystal Ru oxide structure anchored by sulfate, and its 100 mA / cm 2 overpotential is 410 mV, and the attenuation rate is 38.6%.

[0135] By comparing Example 1 with Comparative Example 3, the Ru loading amount of Comparative Example 3 is 34.1% (slightly lower than Example 1), but because the pH of the raw material solution is adjusted to 4.0, the WS2 nanosheet synthesis structure is not complete and loose, and its 100 mA / cm 2 ​​The overpotential rose to 400 mV, and the decay rate was 32.1%. This indicates that the hydrothermal pH deviates from the optimal range (1.5-3.5) and destroys the nano-sheet structure, greatly reducing the utilization rate of active sites.

[0136] By comparing Example 1 with Comparative Example 4, the Ru loading of Comparative Example 4 is 33.3% (lower than Example 1), and sodium sulfite is used instead of sodium hypophosphite as an additive, which is not conducive to the construction of the variable-valence tungsten oxide and the amorphous crystalline Ru oxide structure anchored by sulfate, and the overpotential is 430 mV, and the decay rate is 42.8% at 100 mA / cm 2 The overpotential reached 430 mV, and the decay rate was 42.8%. This shows that the additive directly affects the effective doping of sulfate on the surface, and then weakens the synergistic effect of W and Ru, which significantly reduces the performance.

[0137] By comparing Example 1 with Comparative Example 5, the Ru loading of Comparative Example 5 is 34.9% (close to Example 1), but the Ru addition step is changed to mixing before calcination, and the Ru-O-W fusion interface and SO4 2- anchoring structure are not formed, and the Ru nanophase is aggregated (particle size > 50 nm), and the overpotential is 430 mV, and the decay rate is 42.8% at 100 mA / cm 2 The overpotential reached 450 mV, and the decay rate was 50.2%.

[0138] By comparing Example 1 with Comparative Example 6, the Ru loading of Comparative Example 6 is 35.1% (close to Example 1), but step 1 uses thiourea instead of formula 1A, which easily leads to blocky aggregation of WS2 nanosheets, and the overpotential is 285 mV at 10 mA / cm 2 The overpotential is 285 mV, and the decay rate is 39.5% at 100 mA / cm 2 The overpotential is 420 mV, and the decay rate is 39.5% at 100 h.

[0139] By comparing Example 1 with Comparative Example 7, the Ru loading of Comparative Example 7 is 32.7% (lower than Example 1), and no NaOH is added in step 2, resulting in Ru 3+ cannot be hydrolyzed into Ru(OH)3 colloid, which is not conducive to the construction of the physical and chemical structure of the application, and the overpotential is 300 mV at 10 mA / cm 2 The overpotential is 300 mV, and the decay rate is 48.7% at 100 mA / cm 2 The overpotential is 445 mV, and the decay rate is 48.7% at 100 h.

[0140] By comparing Example 1 with Comparative Example 8, the Ru loading of Comparative Example 8 is 33.2% (lower than Example 1), but step 2 uses an equimolar amount of WO3 instead of WS2 nanosheets, resulting in a weak Ru-W interface, and the overpotential is 295 mV at 10 mA / cm x The overpotential is 295 mV, and the decay rate is 48.7% at 100 mA / cm 2 The overpotential is 295 mV, and the decay rate is 48.7% at 100 mA / cm 2Overpotential 415 mV, 100 h decay rate 36.2%. Characterization shows that WS2 as a S-containing precursor can induce WO3 to multi-valence WO x (WO 4+ / W 5+ / W 6+ , etc.) conversion, and can also provide a stable support substrate for Ru; while WO3 directly participates in the lack of this induction effect, multi-valence WO x The absence of Ru and W between the electronic synergistic effect highlights the importance of WS2 precursor to the control of the loading amount, multi-valence WO x The construction of the importance of the alternative after the synergistic effect is broken down.

[0141] By comparing Example 1 with Comparative Example 9, the Ru loading amount of Comparative Example 9 is 34.7% (close to Example 1), but the step 3 calcination temperature is increased to 500°C, and the results are that the RuO2 crystal grains grow to 15-20 nm, the specific surface area is reduced to 65 m 2 / g, 10 mA / cm 2 Overpotential 260 mV, 100 mA / cm 2 Overpotential 385 mV, 100 h decay rate 29.8%. Studies have found that 350-450°C is the optimal interval for Ru(OH)3 to RuO2 conversion and maintain fine-grained crystal, and when the temperature is out of control to 500°C, RuO2 undergoes significant Ostwald ripening (grain growth), the active site density and specific surface area drop sharply, and the interface bonding is weakened due to grain coarsening, proving that the calcination temperature needs to be strictly controlled at 350-450°C, and exceeding the range will destroy the structural advantages of the catalyst.

[0142] In summary, the compound of formula 1 with a special structure, the auxiliary agent is used to carry out the first stage of the solvothermal reaction at the pH, and the second stage of the solvothermal reaction and the calcination treatment under the assistance of the alkali are combined, so that the multi-valence WO x , the amorphous / crystal RuO2 is constructed in situ; and the material of SO4 2- is modified in situ on the amorphous / crystal RuO2. The present application shows that by the preparation method, the material with the physical and chemical structure characteristics can be constructed in situ, and the material unexpectedly has excellent acid resistance, excellent OER catalytic activity and long cycle stability.

[0143] The above describes the specific embodiments of the present application. However, the present application is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An amorphous / crystalline RuO2 / WO x -SO4 2- Composite material, characterized in that, including multivalent WO x and amorphous / crystalline Ru02; and SO4 2- modified anchored on amorphous / crystalline Ru02; and The multivalent WO x The oxide of tungsten which is tetravalent, pentavalent, hexavalent; the amorphous / crystal RuO2 includes the core of rutile phase RuO2, and the amorphous RuO2 coated on the surface thereof; The amorphous / crystalline RuO2 / WO x -SO4 2- The preparation steps of the composite material include: Step 1: a solution A containing a compound of formula 1, a W source, an auxiliary agent, an acid, and a solvent a is subjected to a first-stage solvothermal reaction to obtain WS2 nanosheets; Formula 1 in formula 1, R1 is an alkyl group with 1-6 carbon atoms; the pH of the solution A is 1.0-3.5; the auxiliary agent is at least one of sodium hypophosphite, potassium hypophosphite, ammonium hypophosphite, and sodium phosphite; in the solution A, the molar ratio of the compound of formula 1, the W source, and the auxiliary agent is 5:0.5-2:0.5-3; the first-stage solvothermal reaction is performed at a temperature of 150-220℃; the first-stage solvothermal reaction is performed for a time of 15-30 h; Step 2: a solution B containing the WS2 nanosheets obtained in Step 1, a base, a Ru source, and a solvent b is subjected to a second-stage solvothermal reaction to coat the WS2 surface with a Ru hydroxide colloid; in the solution B, the molar ratio of Ru / W is 0.8-2.5:1; the second-stage solvothermal reaction is performed at a temperature of 100-200℃; the second-stage solvothermal reaction is performed for a time of 4-8 h; Step 3: The product of Step 2 is calcined at 350-450°C to produce the amorphous / crystalline RuO2 / WO3 composite material of the present application. x -SO4 2- Composite material.

2. The amorphous / crystalline RuO2 / WO x -SO4 2- Composite material, characterized in that, Multivalent state WO x and a molar ratio of Ru / W in amorphous / crystalline RuO2 is 0.8-2.5:1; The mass percentage of SO4 2- 5-12%; the amorphous / crystalline RuO2 has a particle size of 3-8 nm; The amorphous / crystal RuO2 / WO x -SO4 2- The composite material is a three-dimensional porous network structure, the pore size distribution is 20-50 nm, the specific surface area is greater than or equal to 100 m 2 / g, and the average particle size of the particles is 8-15 nm.

3. An amorphous / crystalline RuO2 / WO x -SO4 2- Method for the production of a composite material, characterized in that the steps comprises: Step 1: a solution A containing a compound of formula 1, a W source, an auxiliary agent, an acid, and a solvent a is subjected to a first-stage solvothermal reaction to obtain WS2 nanosheets; Formula 1 in formula 1, R1 is an alkyl group with 1-6 carbon atoms; the pH of the solution A is 1.0-3.5; the auxiliary agent is at least one of sodium hypophosphite, potassium hypophosphite, ammonium hypophosphite, and sodium phosphite; in the solution A, the molar ratio of the compound of formula 1, the W source, and the auxiliary agent is 5:0.5-2:0.5-3; the first-stage solvothermal reaction is performed at a temperature of 150-220℃; the first-stage solvothermal reaction is performed for a time of 15-30 h; Step 2: a solution B containing the WS2 nanosheets obtained in Step 1, a base, a Ru source, and a solvent b is subjected to a second-stage solvothermal reaction to coat the WS2 surface with a Ru hydroxide colloid; in the solution B, the molar ratio of Ru / W is 0.8-2.5:1; the second-stage solvothermal reaction is performed at a temperature of 100-200℃; the second-stage solvothermal reaction is performed for a time of 4-8 h; Step 3: The product of Step 2 is calcined at 350-450°C to produce the amorphous / crystalline RuO2 / WO3 composite material of the present application. x -SO4 2- Composite material.

4. The amorphous / crystalline RuO2 / WO x -SO4 2- Process for the preparation of a composite material, characterized in that, the W source is at least one of sodium tungstate and ammonium tungstate; the solvent a is an aqueous solvent; the acid is an inorganic acid; the base is at least one of sodium hydroxide and potassium hydroxide; the Ru source is at least one of ruthenium trichloride and ruthenium nitrate; the solvent b is an aqueous solvent; the pH of the solution B is 9-10; the calcination process is performed in an oxygen-containing atmosphere; the holding time at the calcination temperature is 1-5 h.

5. The amorphous / crystalline RuO2 / WO x -SO4 2- Process for the preparation of a composite material, characterized in that, The calcination process is performed with microwave assistance.

6. The amorphous / crystalline RuO2 / WO x -SO4 2- Process for the preparation of a composite material, characterized in that, The pressure during the calcination process is 0.2-0.4 MPa.

7. An amorphous / crystalline Ru02 / WO x -SO4 2- The application of the composite material as an OER catalytic material is characterized in that, The amorphous / crystalline RuO2 / WO x -SO4 2- The composite material is the amorphous / crystalline RuO2 / WO x -SO4 2- The composite material, and / or the amorphous / crystalline RuO2 / WO x -SO4 2- The composite material.

8. The amorphous / crystalline RuO2 / WO x -SO4 2- Use of a composite material, characterized in that It is used as an OER catalytic material for electrolytic water hydrogen production in an acidic aqueous solution.

9. The amorphous / crystalline RuO2 / WO x -SO4 2- Use of a composite material, characterized in that It is used as an OER catalytic material for preparing a PEM electrolytic water device for electrolytic water hydrogen production.

10. A PEM electrolyzer water device, characterized in that, comprising amorphous / crystalline RuO2 / WO x -SO4 2- composites or produced thereby, wherein said amorphous / crystalline RuO2 / WO x -SO4 2- composites are amorphous / crystalline RuO2 / WO x -SO4 2- composites and / or produced by the production process according to any one of claims 3 to 6 are amorphous / crystalline RuO2 / WO x -SO4 2- composites.

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