Bismuth tungstate / ruthenium modified tungsten carbide / carbon-carbon self-supporting photoelectric catalytic material and preparation method thereof

Abstract

The invention relates to a bismuth tungstate / ruthenium modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalysis material and a preparation method, and belongs to the field of self-supporting photoelectrocatalysis composites.The preparation method comprises the steps that zinc nitrate, 2-methylimidazole, ruthenium trichloride and sodium tungstate are dissolved in methyl alcohol to obtain a mixed system, the mixed system is subjected to heat preservation treatment at the temperature of 100-180 DEG C, and reaction liquid is obtained; grinding a product in the reaction liquid, and calcining at 800-1000 DEG C in an oxygen-free environment to obtain ruthenium-modified tungsten carbide; the preparation method comprises the following steps: by taking a carbon-carbon substrate as a negative electrode, sequentially and uniformly adhering ruthenium-modified tungsten carbide and bismuth tungstate to the surface of the carbon-carbon substrate by utilizing bismuth tungstate dispersion liquid and ruthenium-modified tungsten carbide dispersion liquid which both contain iodine, so as to obtain the bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectric catalytic material. Good photoelectric oxidation catalytic performance is shown in an alkaline electrolyte.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of self-supporting photoelectrocatalytic composite materials, and particularly relates to a bismuth tungstate / ruthenium modified tungsten carbide / carbon self-supporting photoelectrocatalytic material and a preparation method thereof. BACKGROUND

[0002] Photoelectrocatalysis (PEC) technology is a fast, low-cost and environmentally friendly energy conversion and wastewater treatment technology, and a semiconductor material with light response is usually used as the core catalyst of the technology. In fact, this advanced catalytic technology not only shows certain advancement in the decomposition of water to produce hydrogen, but also shows certain advancement in the decomposition of organic compounds and microorganisms in water. In order to expand the source of hydrogen and improve the hydrogen production rate, researchers use a semiconductor as an electrode to decompose water to produce hydrogen under ultraviolet light irradiation, and propose that using a semiconductor to decompose H2O to produce H2 under the assistance of sunlight is an effective method. The photoelectrocatalytic water decomposition reaction includes three important physical processes: light absorption of a semiconductor photoelectrode to an added light source, separation and migration of photo-generated charges, and redox reaction of water decomposition on the surface of the semiconductor photoelectrode. Among them, the water oxidation reaction on the surface of the semiconductor photoanode is the core of the photoelectrocatalytic water decomposition technology.

[0003] Bismuth tungstate (Bi2WO6) is the simplest Aurivillius-type layered compound, and its crystal structure is composed of (Bi2O2) 2+ and (WO4) 2- two units alternately.(WO4) 2- is a corner-sharing octahedron, which helps to promote the migration of photo-generated electron-hole pairs along the layered structure to the surface of the catalyst, so that the catalyst has strong oxidation ability and fast charge transfer ability, which is of great significance to improve the activity of the catalyst. The band gap of Bi2WO6 is about 2.8 eV, and the response range of sunlight can reach about 450 nm. The 5d orbit of W is its conduction band, and the hybrid orbit of Bi6s and O2p constitutes its valence band. Experiments have proved that the material can be excited by visible light.

[0004] In recent years, researchers have found that an electrocatalyst with water oxidation activity as a cocatalyst can effectively extract the photo-generated holes on the surface of the semiconductor material to the surface of the cocatalyst to promote the separation of photo-generated charges, and the unsaturated chemical microenvironment on the surface provides efficient water oxidation active sites for the water oxidation reaction, thereby improving the water oxidation reaction rate on the surface of the photoanode.

[0005] Tungsten carbide (WC) is considered a promising water splitting catalyst, exhibiting electrocatalytic performance similar to platinum. The photoelectrocatalytic material obtained by compounding WC with Bi2WO6 forms a Schottky junction structure, which helps to promote the separation of photo-generated electron-hole pairs and reduce their recombination opportunities, thereby significantly improving the photocatalytic efficiency. The formation of the Schottky junction also broadens the light absorption range of the material, enabling it to more effectively utilize sunlight and further improving the photoelectro-oxidation catalytic performance. However, during the compounding of WC and Bi2WO6, there is a certain lattice mismatch and charge transfer barrier at the Schottky junction interface, affecting the transport and separation efficiency of photo-generated carriers, and the improvement of photoelectro-oxidation catalytic performance is limited, making it difficult to significantly improve the further application of photoelectrocatalytic water splitting. SUMMARY

[0006] In view of the problems in the prior art, the present application provides a bismuth tungstate / ruthenium modified tungsten carbide / carbon carbon self-supporting photoelectrocatalytic material and a preparation method to solve the problem of limited improvement of photoelectro-oxidation catalytic performance after compounding WC and Bi2WO6. A multi-step method is used to synthesize high-efficiency photoelectrocatalytic material, and the structure of BWO and Ru-WC in the prepared BWO / Ru-WC / CC photoelectrocatalytic material is controllable, which exhibits good photoelectro-oxidation catalytic performance in alkaline electrolyte.

[0007] The present application is realized by the following technical solutions:

[0008] A preparation method of a bismuth tungstate / ruthenium modified tungsten carbide / carbon carbon self-supporting photoelectrocatalytic material, comprising the following steps:

[0009] S1, dissolving zinc nitrate, 2-methyl imidazole, ruthenium trichloride and sodium tungstate in methanol in a molar ratio of (1-10):(1-10):(1-10):(1-10) to obtain a mixed system, and performing heat preservation treatment on the mixed system at 100-180℃ to obtain a reaction liquid;

[0010] S2, grinding the product in the reaction liquid and calcining at 800-1000℃ in an oxygen-free environment to obtain ruthenium modified tungsten carbide;

[0011] S3, using a carbon carbon substrate as a negative electrode, using bismuth tungstate dispersion liquid and ruthenium modified tungsten carbide dispersion liquid both containing iodine, and sequentially attaching the ruthenium modified tungsten carbide and the bismuth tungstate to the surface of the carbon carbon substrate to obtain a bismuth tungstate / ruthenium modified tungsten carbide / carbon carbon self-supporting photoelectrocatalytic material.

[0012] Further improvement of the present application is:

[0013] The concentration of zinc nitrate, 2-methyl imidazole, ruthenium trichloride and sodium tungstate in S1 is 1-10 mol / L.

[0014] The mixed system in S1 is treated at 100-180 DEG C for 4-8h to obtain a reaction solution.

[0015] In S2, the reaction solution is centrifugally washed with anhydrous ethanol and deionized water respectively, and then the obtained solid is dried at 40-70 DEG C for 5-8h to obtain the product.

[0016] The calcination treatment in S2 is performed for 1.5-2.5h.

[0017] The calcination treatment in S2 is performed from room temperature, and the heating rate is 2-10 DEG C / min.

[0018] The bismuth tungstate in S3 is obtained as follows:

[0019] The bismuth nitrate pentahydrate solution and the sodium tungstate solution, both having a concentration of 0.05-1mol / L, are mixed uniformly at a volume ratio of 1:1, and then hydrothermally reacted at 150-200 DEG C for 12-24h, and finally the obtained product is separated, dried and ground in sequence to obtain the bismuth tungstate.

[0020] In the bismuth tungstate dispersion liquid and the ruthenium-modified tungsten carbide dispersion liquid in S3, the concentrations of iodine, bismuth tungstate and ruthenium-modified tungsten carbide are all 3.3-13.33mg / mL.

[0021] In S3, the carbon-carbon matrix is first immersed in the ruthenium-modified tungsten carbide dispersion liquid containing iodine for 10-15min, and then the obtained composite A is taken out, and then immersed in the bismuth tungstate dispersion liquid containing iodine for 10-15min, and then the obtained composite B is taken out and dried to obtain the bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material.

[0022] A bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material obtained by the preparation method of the bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material according to any one of the above.

[0023] Compared with the prior art, the present application has the following beneficial technical effects:

[0024] The application discloses a preparation method of a bismuth tungstate / ruthenium modified tungsten carbide / carbon carbon self-supporting photoelectrocatalytic material, and the ruthenium is grown on the ZIF-8 structure after a solvent thermal reaction of a mixed system, and the sodium tungstate is dissolved and coated around the ZIF-8, and then the Zn in the ZIF-8 is volatilized under high-temperature conditions to form a regular dodecahedron structure, and the Ru replaces part of the Zn, and since the volatilization temperature of the Ru is higher than that of the Zn, the Ru is retained on the carbon skeleton WC after carbonization to prepare the Ru-WC material with better crystallinity, the metallic ruthenium exists in the form of nanoparticles as an active center or an active site on the tungsten carbide surface, the catalytic activity is highlighted, and the stability is ensured, the Bi2WO6 with a light response is sequentially grown on the carbon carbon matrix, the heterojunction is regulated by adjusting the band structure and the surface work function of the material, the bismuth tungstate / ruthenium doped modified tungsten carbide / carbon carbon self-supporting composite material is obtained, the photo-generated electron-hole can be quickly and effectively separated, and the photoelectrocatalytic performance is improved. The application has mild reaction conditions, is easy to realize, and is easy to control. The d electrons of the Ru as a transition metal are hybridized with the d orbits of the WC, the electron concentration is increased, the conductivity is improved, free electrons are released, the carrier concentration is increased, and the prepared BWO / Ru-WC / CC photoelectrocatalytic material exhibits good photoelectrooxidation catalytic performance in an alkaline electrolyte. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The XRD pattern of the BWO prepared in example 1 of the application.

[0026] Figure 2 The XRD pattern of the Ru-WC prepared in example 1 of the application.

[0027] Figure 3 The SEM photo of the BWO prepared in example 1 of the application.

[0028] Figure 4 The SEM photo of the Ru-WC prepared in example 1 of the application.

[0029] Figure 5 The photoelectrocatalytic performance graph of the BWO / Ru-WC / CC prepared in example 1 of the application under the condition that pH is 9.5.

[0030] Figure 6 The SEM photo of the BWO / Ru-WC / CC prepared in example 1 of the application.

[0031] Figure 7 The TEM and corresponding element mapping photo of the Ru-WC prepared in example 1 of the application. PREFERRED EMBODIMENT

[0032] The application will be further described in detail below with specific examples, which are intended to explain but not limit the application.

[0033] The application discloses a preparation method of a bismuth tungstate / ruthenium modified tungsten carbide / carbon carbon self-supporting photoelectrocatalytic material.

[0034] Step 1, weigh bismuth nitrate pentahydrate [Bi (NO3) 3·5H2O], add to 60 mL of deionized water, and stir for 5-10 h to uniformly mix to form a solution A with a concentration of 0.05-1 mol / L.

[0035] Step 2, weigh sodium tungstate (Na2WO4), add to 60 mL of deionized water, and stir for 5-10 h to uniformly mix to form a solution B with a concentration of 0.05-1 mol / L.

[0036] Step 3, after uniformly mixing the solutions A and B, the mixture is loaded into a polytetrafluoroethylene-lined high-pressure reaction kettle, the volume filling ratio is kept between 30% and 60%, the sealed reaction kettle is placed into a homogeneous hydrothermal reaction instrument, the temperature parameter is set to 150-200 ℃, and the reaction time is 12-24 h.

[0037] Step 4, after the reaction is completed, the final reaction product is cooled to room temperature, centrifuged and washed with anhydrous ethanol and deionized water for 3-5 times. The centrifuged substance is placed into a 40-70 ℃ vacuum oven or a freeze-drying box and dried for 5-8 h to obtain powder C. The powder C is ground in a mortar to obtain bismuth tungstate (BWO).

[0038] Step 5, weigh zinc nitrate [Zn (NO3) 2], 2-methylimidazole (2-MIM), ruthenium trichloride (RuCl3) and sodium tungstate (Na2WO4) in sequence, and dissolve in 50-100 mL of methanol, the concentration is 1-10 mol / L, and the mixture is loaded into a polytetrafluoroethylene-lined high-pressure reaction kettle, the sealed reaction kettle is placed into a homogeneous hydrothermal reaction instrument, the temperature parameter is set to 100-180 ℃, and the reaction time is 4-8 h.

[0039] Step 6, after the reaction is completed, the final reaction product is cooled to room temperature, centrifuged and washed with anhydrous ethanol and deionized water for 3-5 times. The centrifuged substance is placed into a 40-70 ℃ vacuum oven or a freeze-drying box and dried for 5-8 h to obtain powder D. The powder D is ground in a mortar to obtain a precursor WO4-Ru@ZIF-8, WO4 refers to the state of Na2WO4 dissolved in methanol, Ru is grown on the ZIF-8 structure through a hydrothermal reaction, and WO4 is coated around the ZIF-8.

[0040] Step 7, the precursor WO4-Ru@ZIF-8 is put into a porcelain boat and calcined under a nitrogen atmosphere, the calcination temperature is 800-1000℃, the holding time is 1.5-2.5h, the heating rate is 2-10℃ / min (from room temperature), and Ru-WC is obtained.

[0041] WO4-Ru@ZIF-8 is calcined at high temperature, and Zn in ZIF-8 is volatilized to form a regular dodecahedron structure (as shown in Figure 4 ), and Ru replaces part of Zn. Since the volatilization temperature of Ru is higher than that of Zn, Ru remains on the carbon skeleton WC after carbonization, and the successful doping of Ru is shown in the mapping diagram of Figure 7 .

[0042] Step 8, take two 250mL beakers, and disperse 0.5-2g BWO and 0.5-2g Ru-WC powder in 150mL isopropyl alcohol respectively, and stir for 12-24h to form uniform mixed dispersions E and F. Then, respectively take 0.5-2g iodine and add to the E dispersion and the F dispersion and stir for 2 days, and the iodine is uniformly dispersed therein. Take a carbon carbon matrix (CC) with an area of 1cm 2 as the negative electrode, and graphite carbon as the positive electrode, and use the hydrothermal electrophoretic deposition device to uniformly attach Ru-WC and BWO on the surface of the CC by using the E dispersion and the F dispersion in sequence (dip in each time for 10-15min, and do not dry after the first time, and dry in a vacuum oven or a freeze-drying oven at 40-70℃ for 5-8h after the second time), wherein the voltage is 4.5-5.5V, the current is 0.5-1.5A, and the running time is 45-75s, and a BWO / Ru-WC / CC photoelectrocatalyst is obtained.

[0043] Example 1:

[0044] Step 1, take bismuth nitrate pentahydrate [Bi(NO3)3·5H2O] and add to 60mL of deionized water, and stir for 10h to form a uniform mixed solution A with a concentration of 0.2mol / L.

[0045] Step 2, take sodium tungstate (Na2WO4) and add to 60mL of deionized water, and stir for 10h to form a uniform mixed solution B with a concentration of 0.2mol / L.

[0046] Step 3, mix solutions A and B uniformly and put into a polytetrafluoroethylene-lined high-pressure reaction kettle, and keep the volume filling ratio at 50%, and put the sealed reaction kettle into a homogeneous hydrothermal reaction instrument, and set the temperature parameter at 180℃, and the reaction time is 24h.

[0047] Step 4, after the reaction is completed, the final reaction is cooled to room temperature, and the reaction is washed with anhydrous ethanol and deionized water for 5 times. The centrifuged material is placed in a 50℃ vacuum oven for 8h to obtain powder C. The powder C is ground in a mortar to obtain bismuth tungstate BWO.

[0048] Figure 1 The diffraction peak of BWO is highly consistent with the characteristic peak position of the Bi2WO6 standard card of PDF #73-2020, indicating that the sample is pure Bi2WO6 phase without obvious impurity phase and has good crystallinity.

[0049] Figure 3 The SEM of BWO shows that BWO is a petal-like agglomerate assembled by sheets, and the sheets are stacked and assembled into a multi-level structure. The single sheet has a thin thickness (combined with the scale 2.00μm, the sheet size is in the sub-micron-micron level), and the large specific surface area is beneficial to charge separation.

[0050] Step 5, weigh zinc nitrate [Zn(NO3)2], 2-methylimidazole (2-MIM), ruthenium trichloride (RuCl3) and sodium tungstate (Na2WO4) and dissolve them in 80mL of methanol. The concentration of zinc nitrate is 5mol / L, the concentration of 2-methylimidazole is 5mol / L, the concentration of ruthenium trichloride is 10mmol / L, and the concentration of sodium tungstate is 5mol / L. Put it into a polytetrafluoroethylene lined high-pressure reaction kettle, and put the sealed reaction kettle into a homogeneous hydrothermal reaction instrument. Set the temperature parameter to 160℃, and the reaction time is 5h.

[0051] Step 6, after the reaction is completed, the final reaction is cooled to room temperature, and the reaction is washed with anhydrous ethanol and deionized water for 5 times. The centrifuged material is placed in a 50℃ vacuum oven for 8h to obtain powder D. The powder D is ground in a mortar to obtain the precursor WO4-Ru@ZIF-8.

[0052] Step 7, the precursor WO4-Ru@ZIF-8 is placed in a porcelain boat and calcined under a nitrogen atmosphere. The calcination temperature is 900℃, the holding time is 2h, and the heating rate is 5℃ / min to obtain Ru-WC.

[0053] Figure 2 The XRD pattern of confirms that the sample contains pure WC and Na2WO4, and the Ru phase does not show a peak in XRD due to low content.

[0054] Figure 4 The SEM image of presents a nanoscale WC agglomerate structure, and the polyhedral morphology is beneficial to the exposure of active sites for catalytic reaction.

[0055] Step 8: Take two 250mL beakers and disperse 1.5g of BWO and 1.5g of Ru-WC powder in 150mL of isopropanol respectively, and stir for 24 hours to form uniformly mixed dispersions E and F. Then weigh 1g of iodine and add it to dispersions E and F respectively, and stir thoroughly for 2 days. [The text abruptly ends here, likely due to an incomplete sentence or missing information.] 2 A carbon-carbon matrix (CC) was used as the negative electrode and graphite carbon as the positive electrode. Ru-WC and BWO were uniformly attached to the CC surface sequentially using a hydrothermal electrophoretic deposition device (immersed in it sequentially for 10 min each time; the first time no drying was required, and the second time drying was carried out in a vacuum oven at 40℃ for 8 h). The voltage was 5V, the current was 1A, and the running time was 1 min, thus obtaining a BWO / Ru-WC / CC photoelectrochemical catalyst.

[0056] Figure 6 In the middle, the bulk material close to the carbon fiber is Ru-WC, and the outer contact material is BWO.

[0057] Figure 5 In this study, a buffer solution prepared with sodium tetraborate (pH = 9.5) was used as the electrolyte, and the photocurrent density-voltage (JV) curves were measured using a photoelectrochemical testing system (PEC 2000, Pofilai). In the 0.6–1.2 V range, the current density gradually increased from near zero, reaching a photocurrent density of 1.05 mA cm⁻¹ at 1.23 V. -2 This indicates that the material has photoelectrocatalytic activity over a wide potential range, has relatively good adaptability, and can initiate and maintain the catalytic reaction without the need for extreme potentials. It also exhibits good photoelectrochemical oxidation catalytic performance in alkaline electrolytes, which is beneficial for its application in practical photoelectrocatalytic systems.

[0058] Example 2

[0059] Step 1: Weigh out bismuth nitrate pentahydrate [Bi(NO3)3·5H2O], add it to 60 mL of deionized water, and stir for 5 h to form a homogeneous solution A with a concentration of 0.05 mol / L.

[0060] Step 2: Weigh sodium tungstate (Na2WO4), add it to 60 mL of deionized water, and stir for 5 h to form a homogeneous solution B with a concentration of 0.05 mol / L.

[0061] Step 3: Mix solutions A and B evenly and load them into a polytetrafluoroethylene-lined high-pressure reactor, maintaining a volume filling ratio of 60%. Place the sealed reactor into a homogeneous hydrothermal reactor, set the temperature parameter to 150℃, and the reaction time to 24h.

[0062] Step 4, after the reaction is completed and cooled to room temperature, the final reaction is centrifuged and washed with anhydrous ethanol and deionized water for 3 times. The centrifuged material is placed in a freeze-drying oven for 8h to obtain powder C. The powder C is ground in a mortar to obtain bismuth tungstate BWO.

[0063] Step 5, weigh zinc nitrate [Zn(NO3)2], 2-methylimidazole (2-MIM), ruthenium trichloride (RuCl3) and sodium tungstate (Na2WO4) and dissolve them in 60mL of methanol. The concentration of zinc nitrate is 1mol / L, the concentration of 2-methylimidazole is 1mol / L, the concentration of ruthenium trichloride is 4mmol / L, and the concentration of sodium tungstate is 1mol / L. Put it into a polytetrafluoroethylene lined high-pressure reaction kettle, put the sealed reaction kettle into a homogeneous hydrothermal reaction instrument, set the temperature parameter to 120℃, and the reaction time is 8h.

[0064] Step 6, after the reaction is completed and cooled to room temperature, the final reaction is centrifuged and washed with anhydrous ethanol and deionized water for 3 times. The centrifuged material is placed in a 70℃ vacuum oven for 5h to obtain powder D. The powder D is ground in a mortar to obtain the precursor WO4-Ru@ZIF-8.

[0065] Step 7, the precursor WO4-Ru@ZIF-8 is placed in a porcelain boat and calcined under a nitrogen atmosphere. The calcination temperature is 800℃, the holding time is 2h, and the heating rate is 2℃ / min to obtain Ru-WC.

[0066] Step 8, take two 250mL beakers, disperse 0.5g of BWO and 0.5g of Ru-WC powder in 150mL of isopropanol solution respectively, and stir for 18h to form a uniform mixed dispersion E and F. Then take 0.8g of iodine and add it to the E dispersion and the F dispersion respectively and stir for 2 days. Take a carbon-carbon matrix (CC) with an area of 1cm 2 as the negative electrode and graphite carbon as the positive electrode. Use the hydrothermal electrophoretic deposition device to uniformly attach Ru-WC and BWO on the surface of CC (immerse in it for 12min each time, the first time without drying, and the second time in a 50℃ vacuum oven for 6h), with a voltage of 5V, a current of 1A, and a running time of 1min. Obtain the BWO / Ru-WC / CC photoelectrocatalyst.

[0067] Example 3:

[0068] Step 1, weigh bismuth nitrate pentahydrate [Bi(NO3)3·5H2O] and add it to 60mL of deionized water, and stir for 9h to form a uniform mixed solution A with a concentration of 1mol / L.

[0069] Step 2: Weigh sodium tungstate (Na2WO4), add it to 60 mL of deionized water, and stir for 9 h to form a homogeneous solution B with a concentration of 1 mol / L.

[0070] Step 3: Mix solutions A and B evenly and load them into a polytetrafluoroethylene-lined high-pressure reactor, maintaining a volume filling ratio of 40%. Place the sealed reactor into a homogeneous hydrothermal reactor, set the temperature parameters to 190℃, and the reaction time to 12h.

[0071] Step 4: After the reaction is complete, cool to room temperature and wash the final reactants four times each with anhydrous ethanol and deionized water by centrifugation. Dry the centrifuged material in a vacuum oven at 60°C for 6 hours to obtain powder C. Grind powder C in a mortar to obtain bismuth tungstate (BWO).

[0072] Step 5: Weigh out zinc nitrate [Zn(NO3)2], 2-methylimidazole (2-MIM), ruthenium trichloride (RuCl3), and sodium tungstate (Na2WO4) and dissolve them in 70 mL of methanol. The concentrations of zinc nitrate, 2-methylimidazole, ruthenium trichloride, and sodium tungstate are 4 mol / L. The solution is then placed in a polytetrafluoroethylene-lined high-pressure reactor. The sealed reactor is then placed in a homogeneous hydrothermal reactor. The temperature parameters are set to 170℃ and the reaction time is 5 h.

[0073] Step 6: After the reaction is complete, cool to room temperature and centrifuge and wash the final reactants five times each with anhydrous ethanol and deionized water. Place the centrifuged material in a freeze-drying oven and dry for 7 hours to obtain powder D. Grind powder D in a mortar to obtain the precursor WO4-Ru@ZIF-8.

[0074] Step 7: Place the precursor WO4-Ru@ZIF-8 into a ceramic boat and calcine it under a nitrogen atmosphere at a temperature of 800℃ for 2 hours. The heating rate is 5℃ / min to obtain Ru-WC.

[0075] Step 8: Take two 250mL beakers and disperse 2g of BWO and 2g of Ru-WC powder in 150mL of isopropanol respectively, and stir for 20 hours to form uniformly mixed dispersions E and F. Then weigh 1g of iodine and add it to dispersions E and F respectively, and stir thoroughly for 2 days. [The text abruptly ends here, likely due to an incomplete sentence or missing information.] 2 A carbon-carbon matrix (CC) was used as the negative electrode and graphite carbon as the positive electrode. Ru-WC and BWO were uniformly attached to the CC surface sequentially using a hydrothermal electrophoretic deposition device (immersed in it sequentially for 14 min each time; the first time was not dried, and the second time was dried in a vacuum oven at 60℃ for 7 h). The voltage was 5V, the current was 1A, and the running time was 1 min, thus obtaining a BWO / Ru-WC / CC photoelectrochemical catalyst.

[0076] Example 4:

[0077] Step 1: Weigh out bismuth nitrate pentahydrate [Bi(NO3)3·5H2O], add it to 60 mL of deionized water, and stir for 7 h to form a homogeneous solution A with a concentration of 0.5 mol / L.

[0078] Step 2: Weigh sodium tungstate (Na2WO4), add it to 60 mL of deionized water, and stir for 7 h to form a homogeneous solution B with a concentration of 0.5 mol / L.

[0079] Step 3: Mix solutions A and B evenly and load them into a polytetrafluoroethylene-lined high-pressure reactor, maintaining a volume filling ratio of 30%. Place the sealed reactor into a homogeneous hydrothermal reactor, set the temperature parameter to 200℃, and the reaction time to 12h.

[0080] Step 4: After the reaction is complete, cool to room temperature and wash the final reactants four times each with anhydrous ethanol and deionized water by centrifugation. Dry the centrifuged material in a vacuum oven at 60°C for 7 hours to obtain powder C. Grind powder C in a mortar to obtain bismuth tungstate (BWO).

[0081] Step 5: Weigh out zinc nitrate [Zn(NO3)2], 2-methylimidazole (2-MIM), ruthenium trichloride (RuCl3), and sodium tungstate (Na2WO4) and dissolve them in 100 mL of methanol. The concentrations of zinc nitrate, 2-methylimidazole, ruthenium trichloride, and sodium tungstate are 8 mol / L, 4 mmol / L, and 8 mol / L, respectively. The solution is then placed in a polytetrafluoroethylene-lined high-pressure reactor. The sealed reactor is then placed in a homogeneous hydrothermal reactor, and the temperature is set to 170℃ for a reaction time of 7 h.

[0082] Step 6: After the reaction is complete, cool to room temperature and centrifuge and wash the final reactants four times each with anhydrous ethanol and deionized water. Dry the centrifuged material in a 60℃ vacuum oven or freeze-drying oven for 8 hours to obtain powder D. Grind powder D in a mortar to obtain the precursor WO4-Ru@ZIF-8.

[0083] Step 7: Place the precursor WO4-Ru@ZIF-8 into a ceramic boat and calcine it under a nitrogen atmosphere at a temperature of 850℃ for 2 hours. The heating rate is 10℃ / min to obtain Ru-WC.

[0084] Step 8: Take two 250mL beakers and disperse 1g of BWO and 1g of Ru-WC powder in 150mL of isopropanol respectively, and stir for 12 hours to form uniformly mixed dispersions E and F. Then weigh 1.5g of iodine and add it to dispersions E and F respectively, and stir thoroughly for 2 days. [The text abruptly ends here, likely due to an incomplete sentence or missing information.] 2The carbon-carbon matrix (CC) as the negative electrode, graphite carbon as the positive electrode, Ru-WC and BWO are uniformly attached to the surface of CC in turn using a hydrothermal electrophoretic deposition device (dipping in each time for 15 min, the first time without drying, and the second time drying in a 70°C freeze-drying oven for 6 h), wherein the voltage is 5 V, the current is 1 A, and the running time is 1 min, to obtain a BWO / Ru-WC / CC photoelectrocatalyst.

Claims

1. A method for preparing a bismuth tungstate / ruthenium modified tungsten carbide / carbon carbon self-supporting photoelectrocatalytic material, characterized in that, The method comprises the following steps: S1, dissolving zinc nitrate, 2-methyl imidazole, ruthenium trichloride and sodium tungstate in methanol in a molar ratio of (1-10):(1-10):(1-10):(1-10) to obtain a mixed system, and performing heat preservation treatment on the mixed system at 100-180°C to obtain a reaction liquid; S2, grinding the product in the reaction liquid and performing calcination treatment at 800-1000°C in an oxygen-free environment to obtain ruthenium-modified tungsten carbide; S3, using a carbon-carbon matrix as a negative electrode, and using a bismuth tungstate dispersion liquid and a ruthenium-modified tungsten carbide dispersion liquid both containing iodine, sequentially attaching the ruthenium-modified tungsten carbide and the bismuth tungstate to the surface of the carbon-carbon matrix to obtain a bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material.

2. The preparation method of the bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material according to claim 1, characterized in that, The concentration of the zinc nitrate, 2-methyl imidazole, ruthenium trichloride and sodium tungstate in S1 is 1-10 mol / L.

3. The preparation method of the bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material according to claim 1, characterized in that, The mixed system in S1 is subjected to heat preservation treatment at 100-180°C for 4-8 h to obtain the reaction liquid.

4. The method of claim 1, wherein the Bi2WO6 / Ru-modified WC / C carbon-carbon self-supporting photoelectrocatalytic material is prepared by the following steps of: (1) preparing a WC / C carbon-carbon self-supporting material; (2) preparing a Bi2WO6 / Ru-modified WC / C carbon-carbon self-supporting material by mixing the WC / C carbon-carbon self-supporting material with Bi2WO6 and Ru. The reaction liquid in S2 is centrifugally washed with anhydrous ethanol and deionized water, and then the obtained solid is dried at 40-70°C for 5-8 h to obtain the product.

5. The preparation method of the bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material according to claim 1, characterized in that, The calcination treatment in S2 is performed for 1.5-2.5 h.

6. The preparation method of the bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material according to claim 1, characterized in that, The calcination treatment in S2 is performed at a temperature rising rate of 2-10°C / min.

7. The preparation method of the bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material according to claim 1, characterized in that, The bismuth tungstate in S3 is obtained by the following process: A bismuth nitrate pentahydrate solution and a sodium tungstate solution, both having a concentration of 0.05-1 mol / L, are mixed in a volume ratio of 1:1, and then subjected to hydrothermal reaction at 150-200°C for 12-24 h, and finally the obtained product is sequentially separated and dried and then ground to obtain the bismuth tungstate.

8. The preparation method of the bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material according to claim 1, characterized in that, The concentration of iodine, bismuth tungstate and ruthenium-modified tungsten carbide in the bismuth tungstate dispersion liquid and the ruthenium-modified tungsten carbide dispersion liquid in S3 is 3.3-13.33 mg / mL.

9. The preparation method of the bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material according to claim 1, characterized in that, In S3, the carbon-carbon matrix is first immersed in the ruthenium-modified tungsten carbide dispersion liquid containing iodine for 10-15 min, then the obtained composite A is taken out, and then the composite B is obtained by immersing the composite A in the bismuth tungstate dispersion liquid containing iodine for 10-15 min, and then drying the composite B to obtain the bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material.

10. A bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material obtained by the preparation method of the bismuth tungstate / ruthenium-modified tungsten carbide / carbon-carbon self-supporting photoelectrocatalytic material in any one of claims 1-9.

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