A V4C3 MXene@BiVO4 photothermal catalytic material and its preparation method and application

Abstract

The present invention provides a V4C3MXene@BiVO4 photothermal catalytic material, its preparation method, and application. The material comprises a BiVO4-encapsulated V4C3MXene structure formed by monoclinic BiVO4 grown on the surface of V4C3MXene. The preparation method comprises: Step 1: dissolving V4AlC3 powder in an HF solution, heating and stirring to perform an acid etching reaction, separating the product, and drying it to obtain a multilayer vanadium carbide powder; Step 2: dissolving bismuth nitrate pentahydrate powder in a dilute nitric acid solution, stirring uniformly, adding the multilayer vanadium carbide powder, and dispersing it uniformly to obtain a reaction precursor solution; Step 3: subjecting the reaction precursor solution to a hydrothermal reaction, separating the product, and drying it to obtain the V4C3MXene@BiVO4 photothermal catalytic material. This material reduces the electron-hole recombination probability of the single two-dimensional V4C3MXene, thereby improving its photothermal catalytic reduction of CO2 conversion rate.

Description

Technical Field

[0001] The present invention belongs to the field of environmental protection and solar energy functional material composites, specifically a V4C3 MXene@BiVO4 photothermal catalytic material and a preparation method and application thereof. Background Art

[0002] Currently, carbon dioxide catalytic conversion technologies are categorized by energy input into electrocatalysis, thermal catalysis, and photocatalysis. Photocatalytic CO2 reduction technology features low energy input and mild reaction conditions, but has a low conversion rate. Thermal catalytic CO2 conversion technology is mature but requires high energy input. Single photocatalytic and thermal catalytic CO2 reduction technologies are unlikely to meet high human expectations, leading to the emergence of catalytic strategies that combine multiple catalytic methods. Photothermal catalysis is a typical example of this new catalytic method, combining the advantages of both light and thermal effects to effectively improve the selectivity and activity of CO2, reducing it to high-value-added products such as CO and CH4.

[0003] Transition metal carbides, nitrides, and carbonitrides (MXenes), a family of graphene-like two-dimensional materials, have gradually developed into photothermal catalytic materials due to their large specific surface area, good chemical stability, and electrical conductivity. They are excellent photothermal carriers and can be used in the catalytic conversion of carbon dioxide to reduce CO2 emissions. However, the low efficiency of photothermal CO2 reduction using a single MXene material has limited its application. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides a V4C3 MXene@BiVO4 photothermal catalytic material, a preparation method and application thereof, which reduces the electron-hole recombination probability of a single two-dimensional V4C3 MXene, thereby effectively improving its photothermal catalytic reduction of CO2 conversion rate.

[0005] The present invention is achieved through the following technical solutions:

[0006] A V4C3 MXene@BiVO4 photothermal catalytic material has a BiVO4-wrapped V4C3 MXene structure formed by monoclinic BiVO4 growing on the surface of V4C3 MXene.

[0007] Preferably, the morphology of the V4C3 MXene@BiVO4 photothermal catalytic material is microspheres with a diameter of 3 to 6 μm.

[0008] The preparation method of the V4C3 MXene@BiVO4 photothermal catalytic material comprises the following steps:

[0009] Step 1: dissolving V4AlC3 powder in HF solution, heating and stirring to perform acid etching reaction, and separating and drying the obtained product to obtain multilayer vanadium carbide powder;

[0010] Step 2: dissolving bismuth nitrate pentahydrate powder in a dilute nitric acid solution, stirring evenly, adding multilayer vanadium carbide powder, and dispersing evenly to obtain a reaction precursor solution;

[0011] Step 3: subjecting the reaction precursor solution to a hydrothermal reaction, separating the product from the reaction solution after the reaction is completed and drying it to obtain a V4C3 MXene@BiVO4 photothermal catalytic material.

[0012] Preferably, in step 2, the molar ratio of V4C3 Mxene to Bi(NO3)3·5H2O is 1:(0.25-1).

[0013] Preferably, in step 2, the concentration of the dilute nitric acid solution is 1M.

[0014] Preferably, in step 3, the hydrothermal reaction temperature is 140-200°C.

[0015] Preferably, in step 3, after the reaction is completed, the product in the obtained reaction solution is washed with anhydrous ethanol and deionized water in sequence, and the washed product is dried at 60-70° C. to obtain a V4C3MXene@BiVO4 photothermal catalytic material.

[0016] The application of the V4C3 MXene@BiVO4 photothermal catalytic material in photothermal carbon dioxide hydrogenation reduction to produce carbon monoxide.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects:

[0018] This invention provides a V4C3 MXene@BiVO4 photothermal catalytic material. The layered structure and large specific surface area of V4C3 MXene give it excellent adsorption properties, but its own photocatalytic performance is very weak. BiVO4, on the other hand, can provide photogenerated electrons or holes, making it an excellent semiconductor for adsorbing acidic gas molecules. This invention allows BiVO4 to grow on the surface of V4C3 MXene, creating a V4C3 MXene@BiVO4 heterojunction composite photothermal catalyst, thereby combining the advantages of both. The Schott junction formed at the BiVO4 / V4C3MXene interface transfers photogenerated electrons from BiVO4 to V4C3 MXene, continuously replenishing the high-energy hot electrons generated by the surface plasmon effect of V4C3 MXene. The photogenerated holes in BiVO4 adsorb acidic CO2 gas. The V4C3MXene surface plasmon effect and interfacial Schott junction effectively separate electrons and holes, reducing the probability of electron-hole recombination within the single two-dimensional V4C3MXene. This synergistic effect with BiVO4, which readily adsorbs acidic CO2 gas, effectively improves the photothermal catalytic reduction of CO2 conversion. The catalyst exhibits high stability and a high photothermal catalytic reduction of carbon dioxide conversion rate, making it suitable for applications in the field of photothermal carbon dioxide hydrogenation.

[0019] The present invention discloses a method for preparing a V4C3 MXene@BiVO4 photothermal catalytic material. V4AlC3 is first subjected to an acid etching reaction to obtain a multilayer V4C3 MXene powder. The vanadium source in the V4C3 MXene then reacts with Bi(NO3)3 in an acid solution to produce an in-situ hydrothermal synthesis of the V4C3 MXene@BiVO4 photothermal catalytic material. This method is simple to operate and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 XRD patterns of V4C3 MXene@BiVO4 materials prepared in Comparative Examples 1 and 2 and Examples 1-4 of the present invention;

[0021] Figure 2 for Figure 1 Enlarged view of the 4.5° to 8° portion in XRD;

[0022] Figure 3 This is the Raman graph of the V4C3 MXene@BiVO4 material prepared in Comparative Example 1 and Examples 1-4 of the present invention;

[0023] Figure 4 This is the SEM image of the V4C3 MXene@BiVO4 material prepared in Example 1 of the present invention;

[0024] Figure 5UV-Vis-NIR DRS spectra of V4C3 MXene@BiVO4 prepared in Comparative Examples 1 and 2 and Examples 1-4 of the present invention;

[0025] Figure 6 Transient photocurrent-time curves of the V4C3 MXene@BiVO4 photothermal catalysts prepared in Comparative Examples 1 and 2 and Examples 1-4 of the present invention under simulated sunlight;

[0026] Figure 7 This is a graph showing the conversion rates of V4C3 MXene@BiVO4 materials prepared in Comparative Examples 1 and 2 and Examples 1-4 of the present invention;

[0027] Figure 8 Surface temperature curve of the sample of the V4C3 MXene@BiVO4 photothermal catalyst prepared in Example 1 of the present invention after irradiation with a Xe lamp at 250°C. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0029] The preparation method of the V4C3 MXene@BiVO4 photothermal catalytic material of the present invention comprises the following steps:

[0030] Step 1: dissolving V4AlC3 powder in HF solution, stirring while heating to perform acid etching reaction, and then separating and drying the resulting product to obtain multilayer vanadium carbide (V4C3) powder;

[0031] Step 2: first dissolve bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) powder in dilute nitric acid solution, stir evenly, add multilayer vanadium carbide powder, and sonicate to obtain a reaction precursor solution;

[0032] Step 3: The precursor solution is subjected to a hydrothermal reaction. After the reaction is completed, the product in the reaction solution is separated and dried to obtain a V4C3 MXene@BiVO4 photothermal catalytic material.

[0033] In step 1, the multilayer V4C3 powder is obtained by the following process:

[0034] V4AlC3 powder was added to HF solution to obtain a sealed mixed system. The concentration of V4AlC3 in the mixed system was 0.05 g / mL. The mixed system was then stirred at 55°C for 48-96 hours. After the reaction was completed, the mixed system was washed with deionized water until the pH of the supernatant was 6-7, and then washed three times with anhydrous ethanol. After centrifugation and drying, a black precipitate was obtained, which was multilayer V4C3 MXene powder.

[0035] In step 2, the molar ratio of V4C3 Mxene and Bi(NO3)3·5H2O is 1:(0.25-1).

[0036] In step 3, the reaction precursor solution undergoes a hydrothermal reaction at 140-200°C. After the reaction is completed, the product in the reaction solution is washed with anhydrous ethanol and deionized water in sequence, and centrifuged 3-5 times. The precipitate after centrifugation is dried at 60-70°C to obtain V4C3 MXene@BiVO4 photothermal catalytic material.

[0037] Photothermal carbon dioxide hydrogenation test:

[0038] 60 mg of the materials prepared in each comparative example and embodiment below were taken respectively in a culture dish with a diameter of 40 mm, a small amount of deionized water was added for stirring and dispersion, and the mixed solution was added dropwise to the culture dish by spin coating and dried in an oven at 60 ° C for 1 h. Subsequently, the photothermal reaction device was heated to 250 ° C, and the culture dish was placed inside the device while keeping the internal seal, and the impurity gas inside the device was removed by continuous 10 min argon gas. Finally, the inlet and outlet valves were closed, and 20 mL of carbon dioxide gas and 60 mL of hydrogen were filled into the normal pressure photothermal catalytic device, and the pressure after inflation was 0.12 MPa. The reaction was carried out for 3 hours, and a sample (1 mL) was added to the gas chromatograph every hour to detect the product content. Among them, the light source used was a 300 W xenon lamp.

[0039] The V4C3 MXene@BiVO4 photothermal catalytic material prepared by the above method is spherical and has enhanced light absorption in the wavelength range of 200-2100nm. It can be used in the photothermal carbon dioxide hydrogenation reduction to produce carbon monoxide, and the CO selectivity is close to 100%.

[0040] Comparative Example 1:

[0041] MAX phase ceramic powder V4AlC3 was added to an HF solution at a concentration of 0.05 g / mL, stirred at 55°C for 96 hours, and centrifuged. The resulting precipitate was washed five times with deionized water and anhydrous ethanol to adjust the pH of the supernatant to 6. The solution was then centrifuged, the precipitate was collected, and vacuum dried at 65°C for 12 hours to obtain multilayer V4C3 MXene powder. The carbon dioxide conversion rate of the multilayer V4C3 MXene powder reached 95.8 μmmol·g -1 ·h -1 , CO selectivity is 96%.

[0042] Comparative Example 2:

[0043] The present invention provides a method for preparing a V4C3 MXene@BiVO4 photothermal catalytic material, comprising the following steps:

[0044] Step 1: MAX phase ceramic powder V4AlC3 was added to an HF solution at a concentration of 0.05 g / mL, stirred at 55°C for 96 hours, and centrifuged. The resulting precipitate was washed five times with deionized water and anhydrous ethanol to adjust the pH of the supernatant to 6. The solution was then centrifuged, the precipitate was collected, and vacuum dried at 65°C for 12 hours to obtain a multilayer V4C3 powder.

[0045] Step 2: Dissolve 1.25 mmol of bismuth nitrate pentahydrate in 20 mL of a 1 M dilute nitric acid solution, stir for 30 min to obtain a mixed solution, then add 315 mg of V4C3, and continue stirring for 30 min to obtain a precursor solution;

[0046] Step 3: Transfer the precursor solution in step 2 to a high-pressure reactor with a polytetrafluoroethylene liner. The filling ratio of the reactor is 70%. The hydrothermal reaction is carried out at 160°C for 12 hours. After the reaction is completed, it is naturally cooled to room temperature. It is centrifuged and washed with deionized water and ethanol three times respectively, and vacuum dried at 65°C for 12 hours to obtain V4C3 MXene@BiVO4 photothermal catalytic material.

[0047] The carbon dioxide conversion rate of V4C3 MXene@BiVO4 photothermal catalytic material reached 75.89 μmmol·g -1 ·h -1 , CO selectivity is close to 100%.

[0048] Example 1:

[0049] The present invention provides a method for preparing a V4C3 MXene@BiVO4 photothermal catalytic material, comprising the following steps:

[0050] Step 1: MAX phase ceramic powder V4AlC3 was added to an HF solution at a concentration of 0.05 g / mL, stirred at 55°C for 96 hours, and centrifuged. The resulting precipitate was washed five times with deionized water and anhydrous ethanol to adjust the pH of the supernatant to 6. The solution was then centrifuged, the precipitate was collected, and vacuum dried at 65°C for 12 hours to obtain a multilayer V4C3 powder.

[0051] Step 2: Dissolve 0.25 mmol of bismuth nitrate pentahydrate in 20 mL of a 1 M dilute nitric acid solution and stir for 30 minutes to obtain a mixed solution. Then, add 255 mg of multilayer V4C3 powder and continue stirring for 30 minutes to obtain a precursor solution.

[0052] Step 3: Transfer the precursor solution in step 2 to a high-pressure reactor with a polytetrafluoroethylene liner. The filling ratio of the reactor is 70%. The hydrothermal reaction is carried out at 160°C for 12 hours. After the reaction is completed, it is naturally cooled to room temperature. It is centrifuged and washed with deionized water and ethanol three times respectively, and vacuum dried at 65°C for 12 hours to obtain V4C3 MXene@BiVO4 photothermal catalytic material.

[0053] The carbon dioxide conversion rate of the V4C3 MXene@BiVO4 photocatalytic material in this example reached 156.51 μmmol·g -1 ·h -1 , CO selectivity is 100%.

[0054] Example 2:

[0055] The present invention provides a method for preparing a V4C3 MXene@BiVO4 photothermal catalytic material, comprising the following steps:

[0056] Step 1: MAX phase ceramic powder V4AlC3 was added to an HF solution at a concentration of 0.05 g / mL, stirred at 55°C for 96 hours, and centrifuged. The resulting precipitate was washed five times with deionized water and anhydrous ethanol to adjust the pH of the supernatant to 6. The solution was then centrifuged, the precipitate was collected, and vacuum dried at 65°C for 12 hours to obtain a multilayer V4C3 powder.

[0057] Step 2: Dissolve 0.5 mmol of bismuth nitrate pentahydrate in 20 mL of a 1 M dilute nitric acid solution and stir for 30 minutes to obtain a mixed solution. Then, add 270 mg of multilayer V4C3 powder and continue stirring for 30 minutes to obtain a precursor solution.

[0058] Step 3: Transfer the precursor solution in step 2 to a high-pressure reactor with a polytetrafluoroethylene liner. The filling ratio of the reactor is 70%. The hydrothermal reaction is carried out at 160°C for 12 hours. After the reaction is completed, it is naturally cooled to room temperature. It is centrifuged and washed with deionized water and ethanol three times respectively, and vacuum dried at 65°C for 12 hours to obtain V4C3 MXene@BiVO4 photothermal catalytic material.

[0059] The carbon dioxide conversion rate of V4C3 MXene@BiVO4 photothermal catalytic material reached 102.54 μmmol·g -1 ·h -1 , CO selectivity is 100%.

[0060] Example 3

[0061] The present invention provides a method for preparing a V4C3 MXene@BiVO4 photothermal catalytic material, comprising the following steps:

[0062] Step 1: MAX phase ceramic powder V4AlC3 was added to an HF solution at a concentration of 0.05 g / mL, stirred at 55°C for 96 hours, and centrifuged. The resulting precipitate was washed five times with deionized water and anhydrous ethanol to adjust the pH of the supernatant to 6. The solution was then centrifuged, the precipitate was collected, and vacuum dried at 65°C for 12 hours to obtain a multilayer V4C3 powder.

[0063] Step 2: Dissolve 0.75 mmol of bismuth nitrate pentahydrate in 20 mL of a 1 M dilute nitric acid solution and stir for 30 min to obtain a mixed solution. Then, add 285 mg of multilayer V4C3 powder and continue stirring for 30 min to obtain a precursor solution.

[0064] Step 3: Transfer the precursor solution in step 2 to a high-pressure reactor with a polytetrafluoroethylene liner. The filling ratio of the reactor is 70%. The hydrothermal reaction is carried out at 160°C for 12 hours. After the reaction is completed, it is naturally cooled to room temperature. It is centrifuged and washed with deionized water and ethanol three times respectively, and vacuum dried at 65°C for 12 hours to obtain V4C3 MXene@BiVO4 photothermal catalytic material.

[0065] The carbon dioxide conversion rate of V4C3 MXene@BiVO4 photothermal catalytic material reached 97.63 μmmol·g -1 ·h -1 , CO selectivity is close to 100%.

[0066] Example 4:

[0067] The present invention provides a method for preparing a V4C3 MXene@BiVO4 photothermal catalytic material, comprising the following steps:

[0068] Step 1: MAX phase ceramic powder V4AlC3 was added to an HF solution at a concentration of 0.05 g / mL, stirred at 55°C for 96 hours, and centrifuged. The resulting precipitate was washed five times with deionized water and anhydrous ethanol to adjust the pH of the supernatant to 6. The solution was then centrifuged, the precipitate was collected, and vacuum dried at 65°C for 12 hours to obtain a multilayer V4C3 powder.

[0069] Step 2: dissolve 1 mmol of bismuth nitrate pentahydrate in 20 mL of a 1 M dilute nitric acid solution, stir for 30 min to obtain a mixed solution, then add 300 mg of V4C3, and continue stirring for 30 min to obtain a precursor solution;

[0070] Step 3: Transfer the precursor solution in step 2 to a high-pressure reactor with a polytetrafluoroethylene liner. The filling ratio of the reactor is 70%. The hydrothermal reaction is carried out at 160°C for 12 hours. After the reaction is completed, it is naturally cooled to room temperature. It is centrifuged and washed with deionized water and ethanol three times respectively, and vacuum dried at 65°C for 12 hours to obtain V4C3 MXene@BiVO4 photothermal catalytic material.

[0071] The carbon dioxide conversion rate of V4C3 MXene@BiVO4 photothermal catalytic material reached 120.89 μmmol·g -1 ·h -1 , CO selectivity is 100%.

[0072] Example 5:

[0073] The present invention provides a method for preparing a V4C3 MXene@BiVO4 photothermal catalytic material, comprising the following steps:

[0074] Step 1: MAX phase ceramic powder V4AlC3 was added to an HF solution at a concentration of 0.05 g / mL, stirred at 55°C for 96 hours, and centrifuged. The resulting precipitate was washed five times with deionized water and anhydrous ethanol to adjust the pH of the supernatant to 6. The solution was then centrifuged, the precipitate was collected, and vacuum dried at 65°C for 12 hours to obtain a multilayer V4C3 powder.

[0075] Step 2: Dissolve 0.25 mmol of bismuth nitrate pentahydrate in 20 mL of a 1 M dilute nitric acid solution and stir for 30 minutes to obtain a mixed solution. Then, add 255 mg of multilayer V4C3 powder and continue stirring for 30 minutes to obtain a precursor solution.

[0076] Step 3: Transfer the precursor solution in step 2 to a high-pressure reactor with a polytetrafluoroethylene liner. The filling ratio of the reactor is 70%. The hydrothermal reaction is carried out at 140°C for 12 hours. After the reaction is completed, it is naturally cooled to room temperature. It is centrifuged and washed with deionized water and ethanol three times respectively, and vacuum dried at 65°C for 12 hours to obtain V4C3 MXene@BiVO4 photothermal catalytic material.

[0077] The photothermal carbon dioxide hydrogenation test shows that the photothermal reduction CO2 conversion rate of this material reaches 103.24μmmol·g -1 ·h -1 , CO selectivity is 100%.

[0078] Example 6:

[0079] The present invention provides a method for preparing a V4C3 MXene@BiVO4 photothermal catalytic material, comprising the following steps:

[0080] Step 1: Add MAX phase ceramic powder V4AlC3 to HF solution at a concentration of 0.05 g / mL, stir at 55°C for 48 hours, centrifuge, and wash the resulting precipitate five times with deionized water and anhydrous ethanol to adjust the pH of the supernatant to 6. The solution is then centrifuged, the precipitate is collected, and vacuum dried at 60°C for 12 hours to obtain multilayer V4C3 powder.

[0081] Step 2: Dissolve 0.25 mmol of bismuth nitrate pentahydrate in 20 mL of a 1 M dilute nitric acid solution, stir for 30 min to obtain a mixed solution, then add 255 mg of V4C3, and continue stirring for 30 min to obtain a precursor solution;

[0082] Step 3: Transfer the precursor solution in step 2 to a high-pressure reactor with a polytetrafluoroethylene lining. The filling ratio of the reactor is 70%. The hydrothermal reaction is carried out at 180°C for 12 hours. After the reaction is completed, it is naturally cooled to room temperature. It is centrifuged and washed with deionized water and ethanol three times respectively, and vacuum dried at 65°C for 12 hours to obtain a V4C3 MXene@BiVO4 photothermal catalytic material.

[0083] The photothermal carbon dioxide hydrogenation test shows that the photothermal reduction CO2 conversion rate of this material reaches 121.53 μmmol·g -1 ·h -1 , CO selectivity is 100%.

[0084] Example 7:

[0085] The present invention provides a method for preparing a V4C3 MXene@BiVO4 photothermal catalytic material, comprising the following steps:

[0086] Step 1: Add MAX phase ceramic powder V4AlC3 to HF solution at a concentration of 0.05 g / mL, stir at 55°C for 72 hours, centrifuge, and wash the resulting precipitate five times with deionized water and anhydrous ethanol to adjust the pH of the supernatant to 6. The solution is then centrifuged, the precipitate is collected, and vacuum dried at 60°C for 12 hours to obtain multilayer V4C3 powder.

[0087] Step 2: Dissolve 0.25 mmol of bismuth nitrate pentahydrate in 20 mL of a 1 M dilute nitric acid solution, stir for 30 min to obtain a mixed solution, then add 255 mg of V4C3, and continue stirring for 30 min to obtain a precursor solution;

[0088] Step 3: The precursor solution in step 2 was transferred to a high-pressure reactor with a polytetrafluoroethylene lining. The filling ratio of the reactor was 70%, and the hydrothermal reaction was carried out at 200°C for 12 hours. After the reaction, it was naturally cooled to room temperature, washed with deionized water and ethanol by centrifugation three times respectively, and vacuum dried at 65°C for 12 hours to obtain V4C3 MXene@BiVO4 photothermal catalytic material.

[0089] The photothermal carbon dioxide hydrogenation test shows that the photothermal reduction CO2 conversion rate of this material reaches 119.89 μmmol·g -1 ·h -1 , CO selectivity is 100%.

[0090] The following is a detailed description of the figures appearing in the present invention.

[0091] Figure 1 The XRD patterns of the spherical V4C3 MXene@BiVO4 photothermal catalytic materials prepared in the present invention are shown in Figure 1. a is the multilayer V4C3 MXene prepared in Comparative Example 1, f is the V4C3MXene@BiVO4 sample synthesized in Comparative Example 2, and b, c, d, and e are the V4C3MXene@BiVO4 samples synthesized according to Examples 1-4, respectively. Figure 1 After compounding, the XRD patterns of the samples of Comparative Example 2 and Examples 1-4 showed diffraction peaks of multilayer V4C3 MXene and monoclinic BiVO4, proving that BiVO4 and V4C3 coexist in V4C3MXene@BiVO4. With the increase of Bi(NO3)3 content, the intensity of the diffraction peak attributed to multilayer V4C3 MXene decreases, while the diffraction peak of BiVO4 is strong and sharp, indicating the formation of BiVO4-encapsulated V4C3 MXene structure. From the local enlarged image ( Figure 2 )2θ=4.5-8°, it was observed that the diffraction peak (002) attributed to multilayer V4C3 MXene in the V4C3 MXene@BiVO4 composite photothermal catalytic material was significantly shifted compared with that of single V4C3, which indicates that there is an interaction between BiVO4 and V4C3.

[0092] Figure 3 This is the Raman spectrum of the V4C3 MXene@BiVO4 photothermal catalyst prepared in the present invention. Among them, a is the multilayer V4C3 MXene prepared in Comparative Example 1, f is the V4C3MXene@BiVO4 sample synthesized in Comparative Example 2, and b, c, d and e are the V4C3MXene@BiVO4 samples synthesized according to Examples 1-4. The V4C3 MXene@BiVO4 photothermal catalyst has a Raman spectrum of 853 cm -1 A new Raman peak appeared at , corresponding to the VO bond, and its intensity increased significantly with the increase of Bi(NO3)3 content, indicating that this was due to the increase of BiVO4 content formed on the surface of multilayer V4C3 MXene.

[0093] Figure 4 The SEM spectrum of the V4C3 MXene@BiVO4 photothermal catalytic material prepared in Example 1 of the present invention shows that the composite material is microspheres with a diameter of 3 to 6 μm.

[0094] Figure 5 This is the UV-Vis-NIR DRS spectrum of the V4C3 MXene@BiVO4 photothermal catalytic material prepared according to the present invention. Figure a represents the multilayer V4C3 MXene prepared in Comparative Example 1, f represents the V4C3 MXene@BiVO4 sample synthesized in Comparative Example 2, and b, c, d, and e represent the V4C3 MXene@BiVO4 samples synthesized according to Examples 1-4. V4C3 MXene exhibits significant light absorption in the 200-2100 nm wavelength range. The light absorption intensity of V4C3 MXene@BiVO4 in this range is lower than that of V4C3 MXene. However, V4C3 MXene@BiVO4 exhibits stable light absorption intensity in the 200-2100 nm wavelength range, while the light absorption intensity of sample f in Comparative Example 2 is significantly reduced in the 600-2100 nm wavelength range. This demonstrates that the BiVO4 formed on the surface of the V4C3 MXene tightly encapsulates the V4C3 MXene.

[0095] Figure 6 Transient photocurrent-time curves of the V4C3 MXene@BiVO4 photothermal catalytic material prepared in this invention under simulated sunlight. Figure a represents the multilayer V4C3 MXene prepared in Comparative Example 1, f represents the V4C3 MXene@BiVO4 sample synthesized in Comparative Example 2, and b, c, d, and e represent the V4C3 MXene@BiVO4 samples synthesized according to Examples 1-4, respectively. Sample b, prepared in Example 1, exhibits the strongest absolute photocurrent response under simulated sunlight, indicating that this composite sample exhibits the highest carrier mobility and separation efficiency.

[0096] Figure 7 This is a graph showing the conversion rate of the V4C3 MXene@BiVO4 photocatalytic material prepared in the present invention. Figure a represents the multilayer V4C3 MXene prepared in Comparative Example 1, f represents the V4C3 MXene@BiVO4 sample synthesized in Comparative Example 2, and b, c, d, and e represent the V4C3 MXene@BiVO4 samples synthesized according to Examples 1-4, respectively. Only CO was detected for all catalysts, with no other carbon-containing products detected. The average photocatalytic conversion rate for a was 95.68 μmol·g -1 ·h -1 The average photothermal catalytic conversion rates of b, c, d, e, and f were 156.51 μmol·g -1 ·h -1 , 102.54 μmol·g -1 ·h -1 , 97.63 μmol·g -1 ·h -1、120.89μmol·g -1 ·h -1 and 75.89 μmol·g -1 ·h -1 (Error bars are standard deviations of three independent tests.) Sample b prepared in Example 1 exhibited the highest conversion rate, reaching 156.51 μmol·gcat -1 ·h -1 , the CO yield is more than twice that of pure V4C3 MXene. In Comparative Example 2, due to the excessive bismuth nitrate content, the V source in the vanadium carbide is converted into bismuth vanadate by default, which is close to a pure phase. Therefore, compared with other composite ratios, the 1.25 ratio sample cannot achieve a relatively high CO yield. The reason for the low CO yield is that after all the V sources are converted into bismuth vanadate, the V source in the vanadium carbide is consumed, the structure of the vanadium carbide itself is destroyed, and the electron holes stored inside are consumed. The amount of electron holes participating in the CO2 reduction reaction is greatly reduced, so the CO yield is reduced.

[0097] Figure 8 The surface temperature curves of the samples after Xe lamp irradiation at 250°C in a gas environment are shown for the V4C3 MXene@BiVO4 photothermal catalytic material of Example 1(b) of the present invention and the multilayer V4C3 MXene of Comparative Example 1(a). After irradiation, the surface temperatures of the two catalysts rose rapidly and reached equilibrium within 7 minutes. After 15 minutes of sunlight irradiation, the surface temperature of sample a (V4C3 MXene) was 369°C, which was 119°C higher than the gas temperature inside the reactor. The surface temperature of sample b (0.25V4C3 MXene@BiVO4) prepared in Example 1 was 379°C, which was 129°C higher than the gas temperature inside the reactor and 10°C higher than the surface temperature of sample a. The higher surface stability temperature further indicates that sample b has a more excellent photothermal effect, which is beneficial for photothermal catalytic CO2 conversion.

[0098] The above is only one embodiment of the present invention, not all or the only embodiment. Any equivalent transformation of the technical solution of the present invention made by ordinary technicians in this field after reading the specification of the present invention is covered by the claims of the present invention.

Claims

1. A method for preparing a V4C3 MXene@BiVO4 photothermal catalytic material, characterized in that: The following steps are involved: Step 1: dissolving V4AlC3 powder in HF solution, heating and stirring to perform acid etching reaction, and separating and drying the obtained product to obtain multilayer vanadium carbide powder; Step 2: dissolving bismuth nitrate pentahydrate powder in a dilute nitric acid solution, stirring evenly, adding multilayer vanadium carbide powder, and dispersing evenly to obtain a reaction precursor solution; Step 3: subjecting the reaction precursor solution to a hydrothermal reaction, separating the product from the reaction solution after the reaction is completed and drying it to obtain a V4C3 MXene@BiVO4 photothermal catalytic material.

2. The method for preparing the V4C3 MXene@BiVO4 photothermal catalytic material according to claim 1, characterized in that: In step 2, the molar ratio of V4C3 Mxene and Bi(NO3)3·5H2O is 1: (0.25~1).

3. The method for preparing the V4C3 MXene@BiVO4 photothermal catalytic material according to claim 1, characterized in that: In step 2, the concentration of the dilute nitric acid solution is 1M.

4. The method for preparing the V4C3 MXene@BiVO4 photothermal catalytic material according to claim 1, characterized in that: In step 3, the hydrothermal reaction temperature is 140-200°C.

5. The method for preparing the V4C3 MXene@BiVO4 photothermal catalytic material according to claim 1, characterized in that: In step 3, after the reaction is completed, the product in the obtained reaction solution is washed with anhydrous ethanol and deionized water in sequence, and the washed product is dried at 60-70° C. to obtain a V4C3 MXene@BiVO4 photothermal catalytic material.

6. The V4C3 MXene@BiVO4 photothermal catalytic material obtained by the preparation method according to any one of claims 1 to 5, characterized in that: It is a BiVO4-wrapped V4C3 MXene structure formed by monoclinic BiVO4 growing on the surface of V4C3 MXene.

7. The V4C3 MXene@BiVO4 photothermal catalytic material according to claim 6, characterized in that The morphology of the V4C3MXene@BiVO4 photothermal catalytic material is microspheres with a diameter of 3~6 μm.

8. Use of the V4C3 MXene@BiVO4 photothermal catalytic material according to claim 6 in photothermal carbon dioxide hydrogenation reduction to produce carbon monoxide.

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