A W18O49 / Nb2CMXene photothermal catalytic material and its preparation method and application

Abstract

The present invention discloses a W 18 O 49 / Nb2C MXene photothermal catalytic material and its preparation method and application, Nb2AlC is etched with HF solution and NaOH solution in sequence to obtain multilayer Nb2CMxene with hydroxyl groups on the surface, and the multilayer Nb2CMxene with hydroxyl groups on the surface and tungsten source are in situ grown into nanowire W in a hydrothermal reaction at 160-240℃. 18 O 49 W loaded between and on the surface of multilayer Nb2C 18 O 49 / Nb2C photothermal catalytic material, using nanowire W 18 The stability of O4 in adsorbing acidic CO2 enhances the W 18 O 49 Conversion rate and selectivity of photothermal catalytic reduction of carbon dioxide by Nb2CMxene powder.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental protection and solar energy utilization functional materials, and relates to photothermal catalytic materials, and specifically to a W 18 O 49 / Nb2C MXene photothermal catalytic material and its preparation method and application. Background Art

[0002] With the acceleration of industrialization, the dramatic increase in global carbon dioxide concentrations has caused a severe greenhouse effect. Therefore, reducing atmospheric carbon dioxide concentrations to mitigate the greenhouse effect has become a major global challenge. To reduce atmospheric carbon dioxide concentrations and achieve resource utilization, converting carbon dioxide into fuels and high-value-added chemical feedstocks can suppress the greenhouse effect and alleviate the energy crisis. Carbon dioxide catalytic reduction technologies include thermal catalysis, photocatalysis, photoelectrocatalysis, and photothermal catalysis.

[0003] Existing photothermal catalysts have a narrow absorption range within the solar spectrum, low utilization of light energy, and low photothermal efficiency, making it difficult to improve light absorption. Secondly, since CO2 reduction is a multi-electron process, the variety of catalysts and the diversity of reaction pathways lead to a large number of products, making it challenging to obtain a single product. Factors such as crystal structure, crystal surface, specific surface area, morphology, surface properties, and particle size directly affect the efficiency and product selectivity of the photothermal catalytic CO2 reduction reaction. Therefore, the preparation of photocatalysts with a wide spectral response, continuous electron supply, and high product methanation remains a very challenging problem. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a 18 O 49 / Nb2C MXene photothermal catalytic material and its preparation method and application, nanofiber-shaped W is in situ prepared by hydrothermal method 18 O 49 Loaded between layers and on the surface of multilayer Nb2CMxene, it improves the conversion rate of photothermal catalytic reduction of carbon dioxide.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A W 18 O 49 The preparation method of Nb2C MXene photothermal catalytic material comprises the following steps:

[0007] Step 1: uniformly mix tungsten chloride and multilayer Nb2C MXene in ethanol at a molar ratio of 1:(1-3) to obtain a precursor solution;

[0008] Step 2: hydrothermally react the precursor solution at 160-240°C for 16-24 hours, then wash and dry the product in the reaction solution to obtain W. 18 O 49 / Nb2C MXene photothermal catalytic materials.

[0009] The present invention also has the following technical features:

[0010] Preferably, the preparation method of the multilayer Nb2C MXene described in step 1 comprises:

[0011] Nb2AlC was added to a 40% HF solution at a ratio of 1 g: 20 mL, and then stirred for 96 hours. The resulting mixed solution was centrifuged and washed with deionized water to obtain a precipitate. A 0.5-1.0 mol / L NaOH solution was added to the precipitate and then stirred for 15-48 hours. The resulting mixed system was centrifuged and washed with deionized water until the pH of the supernatant was 7.3-7.6. The precipitate was then dried at 70 ° C for 12 hours to obtain multilayer Nb2C MXene.

[0012] The volume ratio of the NaOH solution to the HF solution is (35-50):20.

[0013] Preferably, the washing in step 2 is performed by centrifugation washing with deionized water and anhydrous ethanol for 3 to 5 times respectively.

[0014] Preferably, the drying in step 2 is performed at 60-80° C. for 12 hours.

[0015] The present invention also protects a W prepared by the method as described above 18 O 49 / Nb2C MXene photothermal catalytic material, 5-20nm nanofibrous W 18 O 49 Loaded between Nb2C layers and on the surface.

[0016] The present invention also protects W as described above 18 O 49 Application of / Nb2C MXene photothermal catalytic materials in photothermal carbon dioxide hydrogenation reduction to produce carbon monoxide and methane.

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

[0018] The present invention obtains W by hydrothermal in situ growth. 18 O 49 / Nb2C MXene powder, 5~20nm nanofibrous W 18 O 49Loaded between Nb2C MXene layers and on the surface; as a two-dimensional graphene-like material, two-dimensional Nb2C MXene has a unique layered structure, large specific surface area and high carrier mobility, which enables continuous electron supply. Its outstanding metallic conductivity is conducive to rapid charge migration and effective carrier separation. Secondly, the numerous surface end groups on multilayer Nb2C MXenes enable it to react with W 18 O 49 Tightly connected, thus producing a strong photocatalyst, and the unique hydrophilic functional groups can strengthen the interaction with water and CO2 molecules; third, the exposed terminal metal sites of Nb2C MXene have stronger redox ability; fourth, the two-dimensional layered material Nb2C MXene has been proven to have a photothermal effect and is a good photothermal carrier material; and the defective W 18 O 49 Generally presents surface alkalinity and is considered to be a good semiconductor for adsorbing acidic gas molecules. 18 O 49 The presence of surface oxygen vacancies leads to a plasmon-driven active LSPR effect, which can enhance the W 18 O 49 In the photocatalytic activity in the full spectrum region, oxygen vacancies can also serve as reaction sites to improve the reaction process. 18 O 49 and Nb2CMXene were grown in situ by hydrothermal to form heterojunctions, and nanofiber-shaped W 18 O 49 Stable adsorption of acidic CO2, effectively enhancing W 18 O 49 / Nb2C MXene powder photothermal catalytic reduction of carbon dioxide to produce carbon monoxide and methane. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 W prepared in Example 1 18 O 49 / XRD pattern of Nb2C MXene powder;

[0020] Figure 2 W prepared in Example 1 18 O 49 SEM image of / Nb2C MXene powder;

[0021] Figure 3 W prepared in Example 1 18 O 49 UV-Vis-NIR DRS spectrum of / Nb2C MXene powder;

[0022] Figure 4For multilayer Nb2C MXene powder and W prepared in Example 1, Example 2 and Example 3 18 O 49 Conversion rate spectrum of / Nb2CMxene material. DETAILED DESCRIPTION

[0023] The specific contents of the present invention are further explained in detail below with reference to the embodiments.

[0024] Example 1:

[0025] Step 1: Dissolve 1 mol of WCl6 and multilayer Nb2C MXene in 50 ml of ethanol at a molar ratio of 1:2 and stir for 30 min to obtain a precursor solution;

[0026] Among them, the preparation method of multilayer Nb2C MXene includes: adding Nb2AlC to a 40% HF solution at a ratio of 1g:20mL, stirring for 96h, centrifuging the obtained mixed solution and washing the precipitate with deionized water, adding 35mL of a 1.0mol / L NaOH solution to the precipitate, and then stirring for 48h, centrifuging the obtained mixed system and washing with deionized water until the pH of the supernatant is 7.3-7.6, and then drying the precipitate at 70°C for 12h to obtain multilayer Nb2CMxene;

[0027] Step 2: Transfer the precursor solution to a 70 mL polytetrafluoroethylene-lined autoclave and hydrothermally react at 180°C for 24 h. After the reaction, cool naturally to room temperature.

[0028] Step 3: The product in the reaction solution was separated and washed three times with anhydrous ethanol and deionized water respectively, centrifuged and dried at 70 ° C for 12 h to obtain W 18 O 49 / Nb2C Mxene photothermal catalytic materials.

[0029] Example 2:

[0030] Step 1: Dissolve WCl6 and multilayer Nb2CMxene in 50 ml of ethanol at a molar ratio of 1:1 and stir for 30 min to obtain a precursor solution;

[0031] Among them, the preparation method of multilayer Nb2C MXene includes: adding Nb2AlC to a 40% HF solution at a ratio of 1g:20mL, stirring for 96h, centrifuging the obtained mixed solution and washing the precipitate with deionized water, adding 50mL of a 0.5mol / L NaOH solution to the precipitate, and then stirring for 15h, centrifuging the obtained mixed system and washing with deionized water until the pH of the supernatant is 7.3-7.6, and then drying the precipitate at 70°C for 12h to obtain multilayer Nb2CMxene;

[0032] Step 2: Transfer the precursor solution to a 70 mL polytetrafluoroethylene-lined autoclave and heat it in an oven at 180°C for 24 hours. After the reaction is complete, cool it naturally to room temperature.

[0033] Step 3: The product in the reaction solution was separated and washed with anhydrous ethanol and deionized water for 4 times respectively, centrifuged and dried at 70 ° C for 12 h to obtain W 18 O 49 / Nb2C Mxene photothermal catalytic materials.

[0034] Example 3:

[0035] Step 1: Dissolve WCl6 and multilayer Nb2CMxene in 50 ml of ethanol at a molar ratio of 1:3 and stir for 30 min to obtain a precursor solution;

[0036] Among them, the preparation method of multilayer Nb2C MXene includes: adding Nb2AlC to a 40% HF solution at a ratio of 1g:20mL, stirring for 96h, centrifuging the obtained mixed solution and washing the precipitate with deionized water, adding 40mL of a 1.0mol / L NaOH solution to the precipitate, and then stirring for 15h, centrifuging the obtained mixed system and washing with deionized water until the pH of the supernatant is 7.3-7.6, and then drying the precipitate at 70°C for 12h to obtain multilayer Nb2CMxene;

[0037] Step 2: Transfer the precursor solution to a 70 mL polytetrafluoroethylene-lined autoclave and heat it in an oven at 240°C for 16 h. After the reaction, cool it naturally to room temperature.

[0038] Step 3: The product in the reaction solution was separated and washed 5 times with anhydrous ethanol and deionized water respectively, centrifuged and dried at 80 ° C for 12 h to obtain W 18 O 49 / Nb2C Mxene photothermal catalytic materials.

[0039] Example 4:

[0040] Step 1: Dissolve WCl6 and multilayer Nb2CMxene in 50 ml of ethanol at a molar ratio of 1:2 and stir for 30 min to obtain a precursor solution;

[0041] Among them, the preparation method of multilayer Nb2C MXene includes: adding Nb2AlC to a 40% HF solution at a ratio of 1g:20mL, stirring for 96h, centrifuging the obtained mixed solution and washing the precipitate with deionized water, adding 35mL of a 1.0mol / L NaOH solution to the precipitate, and then stirring for 36h, centrifuging the obtained mixed system and washing with deionized water until the pH of the supernatant is 7.3-7.6, and then drying the precipitate at 70°C for 12h to obtain multilayer Nb2CMxene;

[0042] Step 2: Transfer the precursor solution to a 70 mL polytetrafluoroethylene-lined autoclave and heat it in an oven at 160°C for 20 h. After the reaction, cool it naturally to room temperature.

[0043] Step 3: The product in the reaction solution was separated and washed three times with anhydrous ethanol and deionized water respectively, centrifuged and dried at 60 ° C for 12 h to obtain W 18 O 49 / Nb2C Mxene photothermal catalytic materials.

[0044] Example 5:

[0045] Step 1: Dissolve WCl6 and multilayer Nb2CMxene in 50 ml of ethanol at a molar ratio of 1:1 and stir for 30 min to obtain a precursor solution;

[0046] Among them, the preparation method of multilayer Nb2C MXene includes: adding Nb2AlC to a 40% HF solution at a ratio of 1g:20mL, stirring for 96h, centrifuging the obtained mixed solution and washing the precipitate with deionized water, adding 45mL of a 0.6mol / L NaOH solution to the precipitate, and then stirring for 48h, centrifuging the obtained mixed system and washing with deionized water until the pH of the supernatant is 7.3-7.6, and then drying the precipitate at 70°C for 12h to obtain multilayer Nb2CMxene;

[0047] Step 2: Transfer the precursor solution to a 70 mL polytetrafluoroethylene-lined autoclave and heat it in an oven at 160°C for 24 hours. After the reaction is complete, cool it naturally to room temperature.

[0048] Step 3: The product in the reaction solution was separated and washed three times with anhydrous ethanol and deionized water respectively, centrifuged and dried at 70 ° C for 12 h to obtain W 18 O 49 / Nb2C Mxene photothermal catalytic materials.

[0049] Example 6:

[0050] Step 1: Dissolve WCl6 and multilayer Nb2CMxene in 50 ml of ethanol at a molar ratio of 1:3 and stir for 30 min to obtain a precursor solution;

[0051] The preparation method of multilayer Nb2C MXene includes: adding Nb2AlC to a 40% HF solution at a ratio of 1g:20mL, stirring for 96h, centrifuging the obtained mixed solution, washing the precipitate with deionized water, adding 40mL of a 1.0mol / L NaOH solution to the precipitate, stirring for 42h, centrifuging the obtained mixed system, and washing with deionized water until the pH of the supernatant is 7.3-7.6, and then drying the precipitate at 70°C for 12h to obtain multilayer Nb2CMxene;

[0052] Step 2: Transfer the precursor solution to a 70 mL polytetrafluoroethylene-lined autoclave and heat it in an oven at 170°C for 24 hours. After the reaction is complete, cool it naturally to room temperature.

[0053] Step 3: The product in the reaction solution was separated and washed three times with anhydrous ethanol and deionized water respectively, centrifuged and dried at 70 ° C for 12 h to obtain W 18 O 49 / Nb2C Mxene photothermal catalytic materials.

[0054] Example 7:

[0055] Step 1: Dissolve WCl6 and multilayer Nb2CMxene in 50 ml of ethanol at a molar ratio of 1:2 and stir for 30 min to obtain a precursor solution;

[0056] Among them, the preparation method of multilayer Nb2C MXene includes: adding Nb2AlC to a 40% HF solution at a ratio of 1g:20mL, stirring for 96h, centrifuging the obtained mixed solution and washing the precipitate with deionized water, adding 50mL of a 0.5mol / L NaOH solution to the precipitate, and then stirring for 15h, centrifuging the obtained mixed system and washing with deionized water until the pH of the supernatant is 7.3-7.6, and then drying the precipitate at 70°C for 12h to obtain multilayer Nb2CMxene;

[0057] Step 2: Transfer the precursor solution to a 70 mL polytetrafluoroethylene-lined autoclave and heat it in an oven at 180°C for 16 h. After the reaction, cool it naturally to room temperature.

[0058] Step 3: The product in the reaction solution was separated and washed three times with anhydrous ethanol and deionized water respectively, centrifuged and dried at 70 ° C for 12 h to obtain W 18 O 49 / Nb2C Mxene photothermal catalytic materials.

[0059] Example 8:

[0060] Step 1: Dissolve WCl6 and multilayer Nb2C MXene in 50 ml of ethanol at a molar ratio of 1:1 and stir for 30 min to obtain a precursor solution;

[0061] The preparation method of multilayer Nb2C MXene includes: adding Nb2AlC to a 40% HF solution at a ratio of 1g:20mL, stirring for 96h, centrifuging the obtained mixed solution, washing the precipitate with deionized water, adding 45mL of a 0.8mol / L NaOH solution to the precipitate, stirring for 36h, centrifuging the obtained mixed system, and washing with deionized water until the pH of the supernatant is 7.3-7.6, and then drying the precipitate at 70°C for 12h to obtain multilayer Nb2CMxene;

[0062] Step 2: Transfer the precursor solution to a 70 mL polytetrafluoroethylene-lined autoclave and heat it in an oven at 180°C for 20 h. After the reaction, cool it naturally to room temperature.

[0063] Step 3: The product in the reaction solution was separated and washed three times with anhydrous ethanol and deionized water respectively, centrifuged and dried at 65 ° C for 12 h to obtain W 18 O 49 / Nb2C Mxene photothermal catalytic materials.

[0064] Photothermal carbon dioxide hydrogenation test:

[0065] Take 60 mg of W prepared in this example 18 O 49 / Nb2C Mxene photothermal catalytic material is placed in a homemade high-legged culture dish with a diameter of 40mm, a small amount of deionized water is added and stirred to disperse, then placed in a vacuum oven, dried under a vacuum environment of 65℃ and taken out for use. While ensuring that the device is leak-proof, the photothermal reduction device is heated to 250℃, the homemade high-legged culture dish is placed in the photothermal catalytic device, and inert gas is continuously passed through the device for 10 minutes (flow rate 2mL / min). Close the inlet and outlet valves, and fill the atmospheric pressure photothermal catalytic device with 20mL of carbon dioxide gas and 60mL of hydrogen (pressure after filling 0.12MPa). React for 3 hours, and inject a sample (1mL) into the gas chromatograph every hour to detect the carbon monoxide and methane content. Among them, the light source is a 300W xenon lamp, and the auxiliary heating temperature is 250℃.

[0066] Figure 1 is W in Example 1 18 O 49 XRD pattern of / Nb2C Mxene material, in which 2θ=12.9°, 26°, 39.5°, and 41.1° correspond to the characteristic peaks (002), (004), (103), and (104) of the layered structure Nb2AlC (PDF#30-0033), respectively. After Nb2AlC is treated with HF and NaOH, the strongest peak of Nb2AlC at 12.9° almost disappears, and the (004) peak at 26° broadens and moves to a lower angle. This is because the Al atomic layer in the Nb2AlC molecular layer is etched by HF, which reduces the order of the crystal structure, indicating that the obtained Nb2CMxene is a multilayer structure. 18 O 49 Afterwards, the (002) crystal plane diffraction peak continues to shift to a lower angle by about 1.5°, forming a few-layer Nb2C Mxene. As the Nb2CMxene content increases, W 18 O 49 The number of growths increases between layers.

[0067] Figure 2 W prepared in Example 1 18 O 49 SEM image of / Nb2C MXene; layered Nb2C MXene and nanofibrous W can be observed 18 O 49 , W 18 O 49 Length is about 5 to 20 nm; W 18 O 49 Loaded between Nb2C layers and on the surface.

[0068] Figure 3 W prepared in Example 1 18 O 49 UV-Vis-NIR DRS spectrum of / Nb2C MXene, by Figure 3 It can be seen that W 18 O 49 / Nb2C MXene has excellent full spectrum absorption performance in the wavelength range of 200-1800nm, which is due to the 18 O 49 The synergistic surface plasmon effect enables it to have a wider range of solar spectrum response.

[0069] Figure 4 For multilayer Nb2C MXene powder and W prepared in Example 1, Example 2 and Example 3 18 O49 / Nb2CMxene material conversion rate spectrum; Figure 4 It can be seen that at 250℃, 190~1100 wavelength, V CO2 :V H2 =1:3, Nb2C was tested under the reaction conditions. After 3h of photothermal carbon dioxide hydrogenation activity test, the activity and catalyst structure of Examples 1, 2 and 3 remained stable. With the increase of the loading ratio, the conversion rate increased. The conversion rate of Example 2 reached 258.6μmol·g -1 ·h -1 .

[0070] Specifically, under the conditions of a mixed gas of 11%:33%:56% by volume of carbon dioxide, hydrogen, and nitrogen, irradiated at a spectral wavelength of 190-1100 nm for 3 hours and subjected to photothermal carbon dioxide hydrogenation reaction, 47% by volume of methane and 53% by volume of carbon monoxide were generated, with a carbon dioxide conversion rate of 258.6 μmol·g -1 ·h -1 .

Claims

1. A W 18 O 49 The application of / Nb2C MXene photothermal catalytic material in photothermal carbon dioxide hydrogenation reduction to produce carbon monoxide and methane is characterized by: The preparation method of the photothermal catalytic material comprises the following steps: Step 1: uniformly mix tungsten chloride and multilayer Nb2C MXene in ethanol at a molar ratio of 1:(1-3) to obtain a precursor solution; Step 2: hydrothermally react the precursor solution at 160-240°C for 16-24 hours, then wash and dry the product in the reaction solution to obtain W 18 O 49 / Nb2C MXene photothermal catalytic material; The preparation method of multilayer Nb2C MXene described in step 1 is: Nb2AlC was added to a 40% HF solution at a ratio of 1 g: 20 mL, and then stirred for 96 hours. The resulting mixed solution was centrifuged and washed with deionized water to obtain a precipitate. A 0.5-1.0 mol / L NaOH solution was added to the precipitate and then stirred for 15-48 hours. The resulting mixed system was centrifuged and washed with deionized water until the pH of the supernatant was 7.3-7.

6. The precipitate was then dried at 70 ° C for 12 hours to obtain multilayer Nb2C MXene. The volume ratio of the NaOH solution to the HF solution is (35-50):

20.

2. The use according to claim 1, characterized in that The washing in step 2 is performed by centrifugation washing with deionized water and anhydrous ethanol for 3 to 5 times respectively.

3. The use according to claim 1, characterized in that The drying step in step 2 is performed at 60-80° C. for 12 hours.

4. The use according to claim 1, wherein W prepared by the preparation method 18 O 49 5-20 nm nanofibrous W in Nb2C MXene photothermal catalytic materials 18 O 49 Loaded between Nb2C MXene layers and on the surface.

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