Bismuth tungstate / tungsten carbide / foamy copper self-supporting photoelectric catalytic material prepared by liquid-phase hot dipping method and method

Abstract

The invention discloses a bismuth tungstate / tungsten carbide / foamy copper self-supporting photoelectric catalytic material prepared through a liquid-phase hot dipping method and a method, and belongs to the technical field of self-supporting photoelectric catalytic materials.The method comprises the steps that foamy copper is dipped into acetone dispersion liquid of tungsten carbide and then dried, and a compound is obtained; the compound is immersed into iron-doped bismuth tungstate acetone dispersion liquid, the mass ratio of bismuth tungstate in the bismuth tungstate acetone dispersion liquid to tungsten carbide in the tungsten carbide acetone dispersion liquid is (1-5): (1-5), then drying is conducted, and the bismuth tungstate / tungsten carbide / foamy copper self-supporting photoelectric catalytic material is obtained. The Fe-BWO / WxC / CF photoelectrocatalysis material prepared by adopting a multi-step method shows relatively good photoelectrocatalysis performance in a weakly alkaline electrolyte, and is beneficial to the proceeding of an anode oxygen evolution reaction.

Description

Technical Field

[0001] The present invention belongs to the technical field of self-supporting photoelectrocatalytic materials, and particularly relates to a bismuth tungstate / tungsten carbide / copper foam self-supporting photoelectrocatalytic material prepared by a liquid-phase thermal impregnation method and a method therefor. Background Art

[0002] The excessive consumption of fossil fuels has brought about many dilemmas such as energy crisis, global warming, and air pollution. Among many renewable energy sources, solar energy is considered to be the ultimate renewable energy due to its abundance and inexhaustibility. Photoelectrocatalysis is considered to be a promising solar energy conversion approach and is stored in the form of chemical energy.

[0003] Compared with the photocatalytic system, the photoelectrocatalytic system has a higher photoexcited hole-electron separation efficiency due to the support of the bias voltage, and at the same time, the products are easier to separate and collect. On the other hand, due to the increase in power consumption, electrocatalysis often faces higher costs than photoelectrocatalysis. However, the anodic oxygen evolution reaction in photoelectrocatalytic water splitting is a four-electron process, but the slow kinetics leads to poor system efficiency. In addition, the economic value of O2 generated by the oxygen evolution reaction is relatively low, which is not conducive to reducing the overall cost of electrolyzing water. Therefore, designing an efficient photoanode combined with a suitable oxygen evolution alternative reaction is the key issue for the practical application of photoelectrocatalytic technology.

[0004] Bismuth tungstate (Bi2WO6) is a ternary metal oxide. In recent years, it has been one of the most widely used visible-light-driven catalysts due to its wide spectral light response and no secondary pollution after use. Bi2WO6 has an orthorhombic symmetry, and its structure is composed of alternating Bi2O2 lamellae and WO6 octahedron layers connected by vertices. The stacking of these alternating positively and negatively charged lamellae generates an electric field parallel to the lamella (001) plane, thereby promoting the mobility of photogenerated charges in the material. The interaction between the Bi 6s and O 2p orbitals at the top of the valence band of Bi2WO6 accelerates the mobility of photoexcited holes and enhances the oxidation ability, and it has a response to visible light. The smaller particle size and the higher exposure degree of the electron-dominated crystal plane result in a shorter electron transport path to the bulk surface, thus ensuring a lower charge transfer resistance and therefore minimizing energy loss. However, the band gap of pure Bi2WO6 is about 2.8 eV, which is greater than the band gap required for the maximum efficiency of light-initiated water splitting. Therefore, it is difficult for Bi2WO6 to be directly used for photoelectrocatalytic water splitting.

[0005] Due to the limitations of the intrinsic structure of Bi2WO6, currently, the modification of bismuth tungstate mainly adopts a composite method. Among them, a representative one is to composite highly conductive reduced graphene oxide (RGO) with Bi2WO6 to improve its light response. However, as long as RGO is used as an electron acceptor, it can promote the photogenerated electron migration of Bi2WO6 and inhibit recombination, but it does not improve the intrinsic structure of Bi2WO6. Therefore, the improvement effect of the photoelectrocatalytic performance is not significant, and it cannot be applied and popularized in the anodic oxygen evolution reaction. Summary of the Invention

[0006] Aiming at the problems existing in the prior art, the present invention provides a method for preparing a bismuth tungstate / carbide tungsten / copper foam self-supporting photoelectrocatalytic material by a liquid-phase thermal impregnation method, so as to solve the problem that the improvement of the photoelectrocatalytic performance is not obvious when reduced graphene oxide is combined with Bi2WO6. The Fe-BWO / W x C / CF photoelectrocatalytic material prepared by the multi-step method shows good photoelectrocatalytic performance in a weakly alkaline electrolyte, which is beneficial to the anodic oxygen evolution reaction.

[0007] The present invention is realized through the following technical solutions:

[0008] A method for preparing a bismuth tungstate / carbide tungsten / copper foam self-supporting photoelectrocatalytic material by a liquid-phase thermal impregnation method, comprising the following steps:

[0009] S1. Immerse copper foam into the acetone dispersion of tungsten carbide, and then dry it to obtain a composite;

[0010] S2. Immerse the composite into the acetone dispersion of bismuth tungstate doped with iron. The mass ratio of bismuth tungstate in the acetone dispersion of bismuth tungstate to tungsten carbide in the acetone dispersion of tungsten carbide is (1-5):(1-5), and then dry it to obtain the bismuth tungstate / carbide tungsten / copper foam self-supporting photoelectrocatalytic material.

[0011] A further improvement of the present invention lies in:

[0012] The tungsten carbide described in S1 is obtained according to the following process:

[0013] Adjust the pH value of the aqueous solution of dopamine hydrochloride to 1-2, and then add tungsten hexachloride. The molar ratio of tungsten hexachloride to dopamine hydrochloride is 1:(0.5-3), and continuously stir to obtain a precipitate;

[0014] Dry the precipitate and then calcine it at 300-700 °C for 4-6 h in an argon-hydrogen mixed atmosphere to obtain the tungsten carbide.

[0015] The ratio of dopamine hydrochloride to deionized water in the aqueous solution of dopamine hydrochloride is (1 to 250) mol:(10 to 50) mL, and the pH value of the aqueous solution of dopamine hydrochloride is adjusted with 0.5 to 2 mol / L hydrochloric acid.

[0016] S1 Disperse 1 to 5 g of tungsten carbide in 150 mL of acetone and ultrasonicate for 20 to 40 min to obtain a tungsten carbide acetone dispersion.

[0017] S2 Disperse 1 to 5 g of bismuth tungstate doped with iron in 150 mL of acetone and ultrasonicate for 20 to 40 min to obtain a bismuth tungstate doped with iron acetone dispersion.

[0018] S1 First immerse the copper foam into the tungsten carbide acetone dispersion for 45 to 75 s, then take it out and immerse it into the tungsten carbide acetone dispersion for 45 to 75 s again, then take it out, immerse it a total of 8 to 12 times, and then dry it to obtain a composite.

[0019] S2 First immerse the composite into the bismuth tungstate doped with iron acetone dispersion for 45 to 75 s, then take it out and immerse it into the bismuth tungstate doped with iron acetone dispersion for 45 to 75 s again, then take it out, immerse it a total of 8 to 12 times, and then dry it to obtain a bismuth tungstate / tungsten carbide / copper foam self-supporting photocatalytic material.

[0020] The temperatures of the tungsten carbide acetone dispersion in S1 and the bismuth tungstate doped with iron acetone dispersion in S2 are both 150 to 200 °C.

[0021] The bismuth tungstate doped with iron in S2 is obtained as follows:

[0022] Dissolve bismuth nitrate pentahydrate, iron nitrate, and sodium tungstate in deionized water according to a molar ratio of (1000 to 3000):(1000 to 3000):1, then perform hydrothermal treatment at 120 to 200 °C for 6 to 24 h, and then wash the product and dry and grind it in sequence to obtain bismuth tungstate doped with iron.

[0023] The product is alternately filtered and washed 3 to 5 times with deionized water and absolute ethanol respectively, and then vacuum dried or freeze dried at 40 to 70 °C for 12 to 24 h.

[0024] The drying in S1 and S2 is both vacuum drying or freeze drying at 40 to 70 °C for 12 to 24 h.

[0025] A bismuth tungstate / tungsten carbide / copper foam self-supporting photocatalytic material obtained by the method for preparing a bismuth tungstate / tungsten carbide / copper foam self-supporting photocatalytic material by the liquid phase thermal impregnation method described in any one of the above.

[0026] Compared with the prior art, the present invention has the following beneficial technical effects:

[0027] The present invention relates to a method for preparing bismuth tungstate / tungsten carbide / copper foam self-supporting photo-electrocatalytic materials by a liquid-phase thermal impregnation method. Acetone can make tungsten carbide and iron-doped bismuth tungstate fully and evenly dispersed. At the same time, the boiling point of acetone is relatively low, which is beneficial to the subsequent removal; Fe 3+ Doping of Bi2WO6 can change the electronic structure, reduce the energy difference between the conduction band and the valence band, and promote the photo-electrocatalytic performance of Bi2WO6; immersing copper foam into the acetone dispersion of tungsten carbide, W x C is almost coated on the surface of copper foam, and then immersed into the acetone dispersion of iron-doped bismuth tungstate, and Fe-BWO is coated on the surface of W x C. During the drying process, the two are adsorbed together by high-temperature static electricity. Fe-Bi2WO6 on the outermost surface can maximize the utilization of light. Fe-BWO and W x C form a Z-type heterojunction. Photoexcitation makes the electrons on the conduction band of Fe-BWO have a relatively low reduction potential, and the holes on the valence band of WxC have a relatively low oxidation potential. Electrons will transfer from the conduction band of Fe-BWO to the valence band of WxC and recombine with the holes on the valence band of WxC; while the holes with strong oxidizing properties on the valence band of Fe-BWO and the electrons with strong reducing properties on the conduction band of WxC are retained, so that the photo-generated carriers are separated, thereby promoting the photo-electrocatalytic performance. The present invention prepares Fe-BWO / W x C / CF composite materials by a liquid-phase thermal impregnation method. The reaction conditions are mild, easy to implement, and the process is easy to control. Tungsten carbide (WC) has an electronic structure similar to that of Pt. It not only has strong acid resistance, good electrical conductivity and electrocatalytic activity, but also is a potential substitute for the benchmark Pt group metals in alkaline HER electrocatalysis, playing a positive promoting role in the photo-electrocatalytic water splitting reaction. Copper foam (CF) has a high specific surface area, high electron conductivity and porous structure, which is beneficial to improving the exposure of product active sites. At the same time, Fe-BWO and W x C enter the porous structure of CF through impregnation, diffuse inside, and finally realize the regulation of the structure or performance of the catalyst. Highly conductive W x C plays a role in electron conduction, conducting the electrons generated on the surface of photoexcited Fe-Bi2WO6 to the carrier CF, thereby forming a complete path with the photocathode. The present invention grows WC with properties similar to Pt and photo-responsive Bi2WO6 on copper foam by a liquid-phase thermal impregnation method, realizing the rapid and effective separation of photo-generated electrons and holes and improving the photo-electrocatalytic performance, which is beneficial to the anodic oxygen evolution reaction.

[0028] Furthermore, by controlling the ratio of bismuth nitrate pentahydrate, iron nitrate, and sodium tungstate, as well as the reaction temperature and time of the hydrothermal reaction, the morphology, size, and exposure of active sites of Fe-BWO can be well regulated. The Fe-BWO with good crystallinity forms a unique three-dimensional stereoscopic flower-like morphology, which is composed of many thin sheets stacked or connected, and there are certain gaps between the thin sheets, which is beneficial to the mass transfer and diffusion performance of the material. At the same time, the surface of the material is rough, with many small bumps and textures, increasing the specific surface area of the material, which is beneficial to improving the catalytic performance of the material. Description of the Drawings

[0029] Figure 1 XRD pattern of Fe-Bi2WO6 prepared under the conditions of Example 1 of the present invention.

[0030] Figure 2 SEM photograph of Fe-Bi2WO6 prepared under the conditions of Example 1 of the present invention.

[0031] Figure 3 W prepared under the conditions of Example 1 of the present invention x XRD pattern.

[0032] Figure 4 W prepared under the conditions of Example 1 of the present invention x SEM photograph.

[0033] Figure 5 Photocatalytic performance diagram of Fe-BWO / W x C / CF at pH = 9.5. Detailed Description of the Invention

[0034] The following further describes the present invention in detail with specific examples, which are explanations of the present invention rather than limitations.

[0035] A method for preparing a bismuth tungstate / tungsten carbide / copper foam self-supporting photocatalytic material by a liquid-phase thermal impregnation method according to the present invention includes the following steps:

[0036] Step 1, weigh bismuth nitrate pentahydrate [Bi(NO3)3·5H2O] and iron nitrate Fe(NO3)3. Among them, the molar ratio of Bi(NO3)3·5H2O to Fe(NO3)3 is (1000 - 3000):1. Add Bi(NO3)3·5H2O and Fe(NO3)3 to 40 - 100 mL of deionized water and stir for 10 - 30 min to form a uniformly mixed solution A. The concentration of bismuth nitrate pentahydrate is 0.1 - 5 mol / L, and the concentration of iron nitrate is 0.1 - 5 mmol / L.

[0037] Step 2, Weigh sodium tungstate (Na2WO4) and add it to 40 - 100 mL of deionized water, while stirring for 10 - 30 min to form a uniformly mixed solution B. The concentration of sodium tungstate is 0.1 - 5 mol / L.

[0038] Step 3, Mix solution A and B and load them into a polytetrafluoroethylene-lined high-pressure reactor, keeping the volume filling ratio between 30% and 70%. Put the sealed reactor into a homogeneous hydrothermal reactor, set the temperature parameter to 120 - 200 °C, and the reaction time to 6 - 24 h.

[0039] Step 4, After the reaction, cool it to room temperature. Filter and wash the final reactant alternately with deionized water and absolute ethanol for 3 - 5 times. Put the obtained product into a vacuum oven or freeze dryer at 40 - 70 °C and dry it for 12 - 24 h to obtain powder C. Grind the C powder in a mortar to obtain bismuth tungstate doped with iron (Fe - Bi2WO6).

[0040] Step 5, Weigh hydrochloric acid dopamine (DA) and dissolve it in 10 - 50 mL of deionized water, stir for 10 - 30 min, and simultaneously add 0.5 - 2 mol / L hydrochloric acid to adjust the pH value of the solution to 1 - 2 to form a uniformly mixed solution D. The concentration of DA is 0.1 - 5 mol / L.

[0041] Step 6, Add tungsten hexachloride (WCl6) to solution D so that the molar ratio of it to DA is 1:(0.5 - 3). At this time, the concentration of tungsten hexachloride is 0.1 - 5 mol / L, and continuously stir with a stirrer to obtain a yellow-green precipitate. Put the obtained product into a vacuum oven or freeze dryer at 40 - 70 °C and dry it for 12 - 24 h to obtain powder E.

[0042] Step 7, Put powder E into a porcelain boat and calcine it in an argon-hydrogen mixed atmosphere. The calcination temperature is 300 - 700 °C, the calcination time is 4 - 6 h, and the heating rate is 5 - 10 °C / min to obtain a well-crystallized W x C powder, where x = 1, 2, indicating that both WC of hexagonal phase α-WC and W2C of cubic phase β-WC exist in the powder.

[0043] Step 8, Take two 250 mL beakers, disperse 1 - 5 g of Fe - Bi2WO6 and 1 - 5 g of W x C powder in two portions of 150 mL of acetone respectively and ultrasonicate for 20 - 40 min to obtain the acetone dispersion of W x C and the acetone dispersion of Fe - Bi2WO6. Then heat them both to 150 - 200 °C in a muffle furnace. Immerse the copper foam CF with an area of 1 cm 2 completely into W x8 to 12 times in the acetone dispersion of C, staying for 45 to 75 s each time. CF instantaneously adsorbs WxC at high temperature. The multiple impregnations are to make the surface of CF fully adsorb WxC. The obtained composite is placed in a vacuum oven or freeze-drying oven at 40 to 70 °C and dried for 12 to 24 h to evaporate the dispersant, obtaining copper foam adsorbed with W x Copper foam of C is completely immersed in the acetone dispersion of Fe-Bi2WO6 8 to 12 times, staying for 45 to 75 s each time. Fe-BWO is instantaneously adsorbed through high temperature to form a catalyst Fe-BWO / W stably on the surface of copper foam x C. In this way, the same amount of tungsten carbide and Fe-Bi2WO6 can be obtained. Tungsten carbide can promote the hole-electron separation efficiency of bismuth tungstate, and ultimately promote the photoelectrocatalytic performance. If the number of immersions is too small, too little bismuth tungstate will be obtained, and it will not play a role in light response.

[0044] Step 9, Fe-BWO / W on the surface of copper foam x C is placed in a vacuum oven or freeze-drying oven at 40 to 70 °C and dried for 12 to 24 h to evaporate the dispersant, obtaining Fe-BWO / W x C / CF photocatalyst. Highly conductive WxC plays a role in electron conduction, conducting the electrons generated on the surface of photoexcited Fe-Bi2WO6 to the carrier CF, thus forming a complete path with the photocathode. The role of Fe-Bi2WO6 on the outermost surface is to maximize the utilization of light. Fe 3+ Doping of Bi2WO6 can change the electronic structure, reduce the energy difference between the conduction band and valence band, and promote the photoelectrocatalytic performance of Bi2WO6.

[0045] Example 1:

[0046] A method for preparing a bismuth tungstate / tungsten carbide / copper foam self-supporting photocatalytic material by using a liquid-phase thermal impregnation method according to the present invention includes the following steps:

[0047] Step 1, weigh bismuth nitrate pentahydrate [Bi(NO3)3·5H2O] and ferric nitrate Fe(NO3)3. Among them, the molar ratio of Bi(NO3)3·5H2O to Fe(NO3)3 is 2000:1. Add Bi(NO3)3·5H2O and Fe(NO3)3 to 50 mL of deionized water and stir for 30 min to form a uniformly mixed solution A. The concentration of bismuth nitrate pentahydrate is 0.5 mol / L, and the concentration of ferric nitrate is 0.25 mmol / L.

[0048] Step 2, weigh sodium tungstate (Na2WO4) and add it to 50 mL of deionized water, and stir for 30 min at the same time to form a uniformly mixed solution B. The concentration of sodium tungstate is 0.5 mol / L.

[0049] Step 3: Mix solutions A and B and load them into a polytetrafluoroethylene-lined autoclave, keeping the volume filling ratio at 50%. Place the sealed autoclave into a homogeneous hydrothermal reactor, set the temperature parameter to 150 °C, and the reaction time to 12 h.

[0050] Step 4: After the reaction, cool it to room temperature. Filter and wash the final reactant alternately with deionized water and absolute ethanol 5 times. Place the obtained substance in a vacuum oven at 70 °C and dry it for 24 h to obtain powder C. Grind the C powder in a mortar to obtain Fe-Bi2WO6.

[0051] Step 5: Weigh hydrochloric acid dopamine (DA) and dissolve it in 10 mL of deionized water. Stir for 10 min, and at the same time, add 1 mol / L hydrochloric acid to adjust the pH value of the solution to 1 to form a uniformly mixed solution D with a DA concentration of 0.1 mol / L.

[0052] Step 6: Add tungsten hexachloride (WCl6) to solution D such that the molar ratio of WCl6 to DA is 1:1, and continuously stir with a stirrer to obtain a yellow-green precipitate. Place the obtained substance in a freeze dryer and dry it for 12 h to obtain powder E.

[0053] Step 7: Place powder E in a porcelain boat and calcine it under an argon-hydrogen mixed atmosphere. The calcination temperature is 400 °C, the calcination time is 5 h, and the heating rate is 5 °C / min to obtain W x C.

[0054] Step 8: Take two 250 mL beakers, disperse 5 g of Fe-Bi2WO6 and 5 g of W x C powder in two portions of 150 mL of acetone respectively and sonicate for 30 min to obtain an acetone dispersion of W x C and an acetone dispersion of Fe-Bi2WO6. Subsequently, heat them both in a muffle furnace to 200 °C. Immerse a 1 cm 2 foam copper completely into the acetone dispersion of W x C 10 times, staying for 60 s each time. Place the obtained composite in a vacuum oven at 70 °C and dry it for 24 h to obtain foam copper adsorbed with W x C. Then immerse it completely into the acetone dispersion of Fe-Bi2WO6 10 times, staying for 60 s each time, to form a catalyst Fe-BWO / W x C stably on the surface of the foam copper.

[0055] Step 9: Place the Fe-BWO / W x C on the surface of the foam copper in a vacuum oven at 70 °C and dry it for 24 h to obtain the Fe-BWO / W x C / CF photocatalyst.

[0056] AsFigure 1 As shown, the XRD pattern of the C powder prepared in step 4 can be seen, which corresponds exactly to the standard diffraction data of Bi2WO6 in PDF#39-0256, indicating that iron-doped bismuth tungstate (Fe-Bi2WO6) has been successfully prepared.

[0057] As Figure 2 shown, it can be seen that Fe-Bi2WO6 exhibits an obvious flower-like structure, with aggregation in the center and petal-like sheet structures spreading outwards, forming a unique three-dimensional morphology. The flower-like structure is composed of numerous thin sheets stacked or connected, and there are certain gaps between the thin sheets, which can affect the mass transfer and diffusion properties of the material. The overall size of this flower-like structure is close to or slightly smaller than 2 μm, its surface is rough, with many small irregularities and textures, increasing the specific surface area of the material, which is beneficial to improving the catalytic performance of the material.

[0058] As Figure 3 shown, it can be seen that the W x C shows multiple diffraction peaks. By comparison, some diffraction peaks of W x C coincide with or are close to the standard peak positions of W2C and WC, indicating that both W2C and WC phases exist in the sample.

[0059] As Figure 4 shown, it can be seen that the W x C material exhibits an intertwined filamentous or fibrous structure, crisscrossing each other to form a network. These filamentous structures are at the nanoscale, and their fine size endows the material with a large specific surface area, which is helpful for the transport of active substances in photoelectrocatalysis.

[0060] In a traditional three-electrode system (bismuth tungstate / tungsten carbide / copper foam self-supporting electrode as the working electrode, mercury / mercuric oxide electrode as the reference electrode, and platinum sheet electrode as the counter electrode), the electrolyte is a buffer solution (pH = 9.5) prepared using sodium tetraborate drug, and the photocurrent density-voltage (J-V) curve is measured using a photoelectrochemical test system (PEC 2000, Beijing Perfect Light). Among them, the dark reaction is to test the material performance of Example 1 under the condition of no light irradiation. As Figure 5 shown, it can be seen that at an overpotential of 1.23 V, the photocurrent density of Example 1 reaches 0.75 mA cm -2, the photocatalytic performance is the best, and a larger current can be generated at the same potential, and the reaction rate is faster. The current density of Example 4 is relatively the lowest at the same potential, and the photocatalytic performance is weak. The performance of all examples is above the dark reaction curve (dashed line), indicating that light irradiation promotes the electrochemical reaction of these materials, can stimulate the material to generate more carriers, and improve the catalytic activity. The current density at which the dark reaction tends to 0 also indirectly confirms that Example 1 can achieve rapid and effective separation of photo-generated electrons and holes under light irradiation conditions.

[0061] Example 2:

[0062] A method for preparing bismuth tungstate / tungsten carbide / copper foam self-supporting photocatalytic material by liquid-phase thermal impregnation method according to the present invention comprises the following steps:

[0063] Step 1, weigh bismuth nitrate pentahydrate [Bi(NO3)3·5H2O] and iron nitrate Fe(NO3)3, wherein the molar ratio of Bi(NO3)3·5H2O to Fe(NO3)3 is 3000:1. Add Bi(NO3)3·5H2O and Fe(NO3)3 to 60 mL of deionized water and stir for 15 min to form a uniformly mixed solution A. The concentration of bismuth nitrate pentahydrate is 0.1 mol / L, and the concentration of iron nitrate is 0.3 mmol / L.

[0064] Step 2, weigh sodium tungstate (Na2WO4) and add it to 60 mL of deionized water, and stir for 15 min at the same time to form a uniformly mixed solution B. The concentration of sodium tungstate is 0.1 mol / L.

[0065] Step 3, mix solution A and B and load them into a polytetrafluoroethylene-lined autoclave, and keep the volume filling ratio at 30%. Put the sealed autoclave into a homogeneous hydrothermal reactor, set the temperature parameter to 120 °C, and the reaction time to 12 h.

[0066] Step 4, after the reaction is completed, cool it to room temperature, and alternately filter and wash the final reactant 5 times with deionized water and absolute ethanol. Put the obtained substance into a vacuum oven at 50 °C and dry it for 12 h to obtain powder C. Grind the C powder in a mortar to obtain Fe-Bi2WO6.

[0067] Step 5, weigh dopamine hydrochloride (DA) and dissolve it in 15 mL of deionized water, stir for 15 min, and at the same time add 0.5 mol / L hydrochloric acid to adjust the pH value of the solution to 2 to form a uniformly mixed solution D. The concentration of DA is 0.1 mol / L.

[0068] Step 6: Add tungsten hexachloride (WCl6) to solution D such that the molar ratio of WCl6 to DA is 1:0.5, and continuously stir with a stirrer to obtain a yellow-green precipitate. Place the obtained material in a vacuum oven at 50 °C for 12 h to obtain powder E.

[0069] Step 7: Place powder E in a porcelain boat and calcine it in a mixed argon-hydrogen atmosphere at a calcination temperature of 300 °C for 4 h with a heating rate of 5 °C / min to obtain WC. x C.

[0070] Step 8: Take two 250 mL beakers, disperse 1 g of Fe-Bi2WO6 and 1 g of WC powder in two portions of 150 mL of acetone respectively and ultrasonicate for 20 min to obtain an acetone dispersion of WC and an acetone dispersion of Fe-Bi2WO6. Subsequently, heat both to 150 °C in a muffle furnace. Immerse a 1 cm2 copper foam completely into the acetone dispersion of WC ten times, with each immersion lasting 45 s. Place the obtained composite in a vacuum oven at 50 °C for 12 h to obtain copper foam adsorbed with WC. Then immerse it completely into the acetone dispersion of Fe-Bi2WO6 10 times, with each immersion lasting 45 s, to form a catalyst Fe-BWO / WC stably on the surface of the copper foam. x C powder are respectively dispersed in two portions of 150 mL of acetone and ultrasonically treated for 20 min to obtain an acetone dispersion of WC and an acetone dispersion of Fe-Bi2WO6. Subsequently, both are heated to 150 °C in a muffle furnace. Immerse a 1 cm x 2 copper foam completely into the acetone dispersion of WC ten times, with each immersion lasting 45 s. Place the obtained composite in a vacuum oven at 50 °C for 12 h to obtain copper foam adsorbed with WC. Then immerse it completely into the acetone dispersion of Fe-Bi2WO6 10 times, with each immersion lasting 45 s, to form a catalyst Fe-BWO / WC stably on the surface of the copper foam. 2 2 copper foam completely into the acetone dispersion of WC ten times, with each immersion lasting 45 s. Place the obtained composite in a vacuum oven at 50 °C for 12 h to obtain copper foam adsorbed with WC. Then immerse it completely into the acetone dispersion of Fe-Bi2WO6 10 times, with each immersion lasting 45 s, to form a catalyst Fe-BWO / WC stably on the surface of the copper foam. x C powder are respectively dispersed in two portions of 150 mL of acetone and ultrasonically treated for 20 min to obtain an acetone dispersion of WC and an acetone dispersion of Fe-Bi2WO6. Subsequently, both are heated to 150 °C in a muffle furnace. Immerse a 1 cm x C powder are respectively dispersed in two portions of 150 mL of acetone and ultrasonically treated for 20 min to obtain an acetone dispersion of WC and an acetone dispersion of Fe-Bi2WO6. Subsequently, both are heated to 150 °C in a muffle furnace. Immerse a 1 cm x C powder are respectively dispersed in two portions of 150 mL of acetone and ultrasonically treated for 20 min to obtain an acetone dispersion of WC and an acetone dispersion of Fe-Bi2WO6. Subsequently, both are heated to 150 °C in a muffle furnace. Immerse a 1 cm

[0071] Step 9: Place the obtained Fe-BWO / WC in a vacuum oven at 50 °C for 12 h to obtain a Fe-BWO / WC / CF photocatalyst. x C in a vacuum oven at 50 °C for 12 h to obtain a Fe-BWO / WC / CF photocatalyst. x C / CF photocatalyst.

[0072] Example 3:

[0073] A method for preparing a bismuth tungstate / tungsten carbide / copper foam self-supporting photocatalytic material by a liquid-phase thermal impregnation method according to the present invention comprises the following steps:

[0074] Step 1: Weigh bismuth nitrate pentahydrate [Bi(NO3)3·5H2O] and iron nitrate Fe(NO3)3, wherein the molar ratio of Bi(NO3)3·5H2O to Fe(NO3)3 is 1000:1. Add Bi(NO3)3·5H2O and Fe(NO3)3 to 80 mL of deionized water and stir for 30 min to form a uniformly mixed solution A. The concentration of bismuth nitrate pentahydrate is 2.5 mol / L, and the concentration of iron nitrate is 2.5 mmol / L.

[0075] Step 2: Weigh sodium tungstate (Na2WO4) and add it to 80 mL of deionized water. Stir for 30 min simultaneously to form a uniformly mixed solution B, with the concentration of sodium tungstate being 2.5 mol / L.

[0076] Step 3: Mix solution A and B and load them into a polytetrafluoroethylene-lined autoclave, keeping the volume filling ratio at 60%. Place the sealed autoclave into a homogeneous hydrothermal reactor, set the temperature parameter to 160 °C, and the reaction time to 24 h.

[0077] Step 4: After the reaction, cool it to room temperature. Filter and wash the final reactants alternately with deionized water and absolute ethanol 3 times. Put the obtained substance into a freeze-drying oven and dry it for 12 h to get powder C. Grind the C powder in a mortar to obtain Fe-Bi2WO6.

[0078] Step 5: Weigh hydrochloric acid dopamine (DA) and dissolve it in 30 mL of deionized water. Stir for 30 min, and simultaneously add 1 mol / L hydrochloric acid to adjust the pH value of the solution to 1 to form a uniformly mixed solution D, with the concentration of DA being 1.5 mol / L.

[0079] Step 6: Add tungsten hexachloride (WCl6) to solution D so that the molar ratio of it to DA is 1:3, and continuously stir with a stirrer to obtain a yellow-green precipitate. Put the obtained substance into a freeze-drying oven and dry it for 24 h to get powder E.

[0080] Step 7: Put powder E into a porcelain boat and calcine it under an argon-hydrogen mixed atmosphere. The calcination temperature is 500 °C, the calcination time is 6 h, and the heating rate is 10 °C / min to obtain W x C.

[0081] Step 8: Take two 250 mL beakers, disperse 2 g of Fe-Bi2WO6 and 2 g of W x C powder in two portions of 150 mL of acetone respectively and ultrasonicate for 40 min to obtain the acetone dispersion of W x C and the acetone dispersion of Fe-Bi2WO6. Subsequently, heat them both to 150 °C in a muffle furnace. Immerse the copper foam with an area of 1 cm 2 completely into the acetone dispersion of W x C ten times, staying for 75 s each time. Put the obtained composite into a 70 °C vacuum oven and dry it for 12 h to get the copper foam adsorbed with W x C. Then immerse it completely into the acetone dispersion of Fe-Bi2WO6 10 times, staying for 75 s each time, to form the catalyst Fe-BWO / W x C stably on the surface of the copper foam.

[0082] Step 9: The obtained Fe-BWO / W xC was dried in a vacuum oven at 70 °C for 12 h to obtain Fe-BWO / W x C / CF photocatalyst.

[0083] Example 4

[0084] A method for preparing bismuth tungstate / tungsten carbide / copper foam self-supporting photocatalytic material by liquid-phase thermal impregnation method according to the present invention comprises the following steps:

[0085] Step 1: Weigh bismuth nitrate pentahydrate [Bi(NO3)3·5H2O] and iron nitrate Fe(NO3)3. The molar ratio of Bi(NO3)3·5H2O to Fe(NO3)3 is 2000:1. Add Bi(NO3)3·5H2O and Fe(NO3)3 to 100 mL of deionized water and stir for 30 min to form a uniformly mixed solution A. The concentration of bismuth nitrate pentahydrate is 5 mol / L, and the concentration of iron nitrate is 2.5 mmol / L.

[0086] Step 2: Weigh sodium tungstate (Na2WO4) and add it to 100 mL of deionized water. Stir for 30 min simultaneously to form a uniformly mixed solution B. The concentration of sodium tungstate is 5 mol / L.

[0087] Step 3: Mix solution A and B and load them into a polytetrafluoroethylene-lined autoclave, keeping the volume filling ratio at 70%. Place the sealed autoclave in a homogeneous hydrothermal reactor, set the temperature parameter to 200 °C, and the reaction time to 6 h.

[0088] Step 4: After the reaction, cool to room temperature. Filter and wash the final reactant alternately with deionized water and absolute ethanol 3 times. Place the obtained substance in a freeze-drying oven and dry for 24 h to obtain powder C. Grind the C powder in a mortar to obtain Fe-Bi2WO6.

[0089] Step 5: Weigh hydrochloric acid dopamine (DA) and dissolve it in 50 mL of deionized water. Stir for 30 min, and at the same time, add 2 mol / L hydrochloric acid to adjust the pH value of the solution to 1 to form a uniformly mixed solution D. The concentration of DA is 5 mol / L.

[0090] Step 6: Add tungsten hexachloride (WCl6) to solution D so that the molar ratio of it to DA is 1:2, and continuously stir with a stirrer to obtain a yellow-green precipitate. Place the obtained substance in a freeze-drying oven and dry for 24 h to obtain powder E.

[0091] Step 7: Place powder E in a porcelain boat and calcine it in an argon-hydrogen mixed atmosphere. The calcination temperature is 700 °C, the calcination time is 5.5 h, and the heating rate is 10 °C / min to obtain W x C.

[0092] Step 8: Take two 250 mL beakers, disperse 2.5 g of Fe-Bi2WO6 and 2.5 g of W x C powder in two portions of 150 mL of acetone and ultrasonicate for 30 min to obtain a W x C acetone dispersion and an Fe-Bi2WO6 acetone dispersion. Subsequently, heat both to 150 °C in a muffle furnace. Immerse a 1 cm 2 foamed copper completely into the W x C acetone dispersion ten times, with each immersion lasting 60 s. Place the resulting composite in a freeze dryer and dry for 24 h to obtain foamed copper adsorbed with W x C. Then immerse it completely into the Fe-Bi2WO6 acetone dispersion 10 times, with each immersion lasting 60 s, to form a catalyst Fe-BWO / W x C that is stable on the surface of the foamed copper.

[0093] Step 9: Place the obtained Fe-BWO / W x C in a freeze dryer and dry for 24 h to obtain an Fe-BWO / W x C / CF photocatalyst.

Claims

1. A method for preparing a bismuth tungstate / tungsten carbide / copper foam self-supporting photoelectrocatalytic material by a liquid-phase thermal impregnation method, characterized in that, It includes the following steps: S1. Immerse the copper foam into the acetone dispersion of tungsten carbide, and then dry it to obtain a composite; S2. Immerse the composite into the acetone dispersion of bismuth tungstate doped with iron. The mass ratio of bismuth tungstate in the acetone dispersion of bismuth tungstate to tungsten carbide in the acetone dispersion of tungsten carbide is (1-5):(1-5), and then dry it to obtain the bismuth tungstate / tungsten carbide / copper foam self-supporting photo-electrocatalytic material.

2. The method for preparing the bismuth tungstate / tungsten carbide / copper foam self-supporting photo-electrocatalytic material by the liquid-phase thermal impregnation method according to claim 1, wherein, The tungsten carbide described in S1 is obtained according to the following process: Adjust the pH value of the aqueous solution of dopamine hydrochloride to 1-2, and then add tungsten hexachloride. The molar ratio of tungsten hexachloride to dopamine hydrochloride is 1:(0.5-3), and continuously stir to obtain a precipitate; Dry the precipitate and then calcine it at 300-700 °C for 4-6 h in an argon-hydrogen mixed atmosphere to obtain the tungsten carbide.

3. The method for preparing a bismuth tungstate / tungsten carbide / copper foam self-supporting photoelectrocatalytic material by the liquid-phase thermal impregnation method according to claim 2, characterized in that, The ratio of dopamine hydrochloride to deionized water in the aqueous solution of dopamine hydrochloride is (1-250) mol:(10-50) mL, and the pH value of the aqueous solution of dopamine hydrochloride is adjusted using 0.5-2 mol / L hydrochloric acid.

4. The method for preparing a bismuth tungstate / tungsten carbide / copper foam self-supporting photo-electrocatalytic material by a liquid-phase thermal impregnation method according to claim 1, characterized in that In S1, disperse 1-5 g of tungsten carbide in 150 mL of acetone and ultrasonicate for 20-40 min to obtain the acetone dispersion of tungsten carbide; In S2, disperse 1-5 g of bismuth tungstate doped with iron in 150 mL of acetone and ultrasonicate for 20-40 min to obtain the acetone dispersion of bismuth tungstate doped with iron.

5. The method for preparing a bismuth tungstate / tungsten carbide / copper foam self-supporting photo-electrocatalytic material by a liquid-phase thermal impregnation method according to claim 1, characterized in that, In S1, first immerse the copper foam into the acetone dispersion of tungsten carbide for 45-75 s, then take it out and immerse it into the acetone dispersion of tungsten carbide for 45-75 s again, then take it out, immerse it a total of 8-12 times, and then dry it to obtain a composite; In S2, first immerse the composite into the acetone dispersion of bismuth tungstate doped with iron for 45-75 s, then take it out and immerse it into the acetone dispersion of bismuth tungstate doped with iron for 45-75 s again, then take it out, immerse it a total of 8-12 times, and then dry it to obtain the bismuth tungstate / tungsten carbide / copper foam self-supporting photo-electrocatalytic material.

6. The method for preparing a bismuth tungstate / tungsten carbide / copper foam self-supporting photoelectrocatalytic material by a liquid-phase thermal impregnation method according to claim 1, characterized in that, The temperature of the acetone dispersion of tungsten carbide described in S1 and the acetone dispersion of bismuth tungstate doped with iron described in S2 are both 150-200 °C.

7. The method for preparing a bismuth tungstate / tungsten carbide / copper foam self-supporting photo-electrocatalytic material by a liquid-phase thermal impregnation method according to claim 1, characterized in that, The bismuth tungstate doped with iron described in S2 is obtained according to the following process: Dissolve bismuth nitrate pentahydrate, iron nitrate, and sodium tungstate in deionized water according to the molar ratio of (1000-3000):(1000-3000):1, then perform hydrothermal treatment at 120-200 °C for 6-24 h, and then wash the product and dry and grind it in sequence to obtain the bismuth tungstate doped with iron.

8. The method for preparing a bismuth tungstate / tungsten carbide / copper foam self-supporting photoelectrocatalytic material by the liquid-phase thermal impregnation method according to claim 7, characterized in that, The product is alternately filtered and washed 3-5 times with deionized water and absolute ethanol respectively, and then vacuum dried or freeze dried at 40-70 °C for 12-24 h.

9. The method for preparing a bismuth tungstate / tungsten carbide / copper foam self-supporting photo-electrocatalytic material by a liquid-phase thermal impregnation method according to claim 1, characterized in that, The drying in S1 and S2 is both vacuum drying or freeze drying at 40-70 °C for 12-24 h.

10. A bismuth tungstate / tungsten carbide / copper foam self-supporting photo-electrocatalytic material obtained by the method for preparing a bismuth tungstate / tungsten carbide / copper foam self-supporting photo-electrocatalytic material by the liquid-phase thermal immersion method according to any one of claims 1-9.

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