An organic hydrophobic group metal carbide coupling film, a preparation method and application thereof

Abstract

The application provides an organic hydrophobic group metal carbide coupling film and a preparation method and application thereof, and belongs to the technical field of photocatalytic materials.The Mo powder is dispersed in ethanol, first stirring is carried out, and a H2O2 solution is slowly added, then continuous stirring is carried out, and a blue Mo ink solution is obtained; then the obtained blue Mo ink solution is injected into potassium chloride, and then glucose is added, and the mixture is stirred vigorously in a water bath until dry; finally, after the dried mixture is calcined under a hydrogen-argon mixture atmosphere and cooled to room temperature, washing is carried out, and Mo2C-C x The coupling film, wherein X is the mass of the glucose corresponding to the 0.1g Mo powder added.The application utilizes the catalytic characteristics of Mo2C and the synergistic effect of the enhanced carbon layer PTT, so that the obtained catalyst can realize CO2 reduction in a wide wavelength range including ultraviolet-near infrared light.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photocatalytic materials, in particular to an organic hydrophobic group metal carbide coupling film and a preparation method and application thereof. BACKGROUND

[0002] In recent years, simulating "artificial photosynthesis" to convert carbon dioxide into valuable chemicals and fuels through photocatalysis by sunlight has the advantages of simplicity, high efficiency, and no pollution. Compared with emerging photocatalytic hydrogen production systems, photocatalytic hydrogen production systems achieve a solar-to-hydrogen (STH) conversion efficiency of ~ 9.2% under concentrated xenon lamp illumination of 3800 mW / cm 2 , and a solar-to-hydrogen (STH) conversion efficiency of ~ 6.2% under high concentrated natural light intensity of about 16070 mW / cm 2 , and the solar-to-fuel (STF) conversion efficiency of the photocatalytic CO2 reduction system is often ignored. The fundamental reason for this difference is that water splitting is thermodynamically and kinetically superior to CO2 reduction, which requires additional energy to overcome the significant ~ 750 kJ / mol C=O dissociation energy. This energy requirement takes precedence over high-energy photons in the radiative transition in the photocatalytic process, making low-frequency, low-energy photons unable to participate in the carbon dioxide reduction reaction, resulting in energy waste. Solving these challenges is crucial for the development of practical and efficient photocatalytic CO2 reduction systems.

[0003] Photo-thermal conversion (PTT) is a less explored aspect of developing carbon dioxide photocatalytic reduction systems, which is a process in which a material absorbs light and converts it into heat. Enhanced PTT conversion can improve photocatalytic efficiency by providing the energy required to overcome activation barriers and activate reaction pathways. This approach has been successful in producing hydrogen and carbon dioxide photocatalytic reduction in full water splitting. However, a major challenge still exists: most catalytic materials can only be activated by ultraviolet-visible (UV-vis) light, making near-infrared (NIR) low-energy photons (about 50% of solar energy) not fully utilized in current systems. SUMMARY

[0004] Therefore, the present application aims to provide an organic hydrophobic group metal carbide coupling film and a preparation method and application thereof. The organic hydrophobic group metal carbide coupling film prepared by a simple high-temperature calcination method can achieve CO2 reduction in a wide wavelength range including ultraviolet-near infrared light.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions: a preparation method of an organic hydrophobic group metal carbide coupling film, comprising the following steps:

[0006] (1) dispersing Mo powder in ethanol, stirring for the first time and slowly adding H2O2 solution, then continuously stirring to obtain a blue Mo ink solution;

[0007] (2) injecting the blue Mo ink solution obtained in step (1) into potassium chloride, then adding glucose in a water bath and stirring the mixture until dry;

[0008] (3) washing the mixture after drying in step (2) and growing in situ to obtain Mo2C-C x coupling thin film, wherein X is the mass of 0.1 g of Mo powder corresponding to the mass of added glucose.

[0009] In some embodiments, the mass-volume ratio of the Mo powder, ethanol and H2O2 solution in step (1) is 0.1 g: 24 mL: 0.75 mL.

[0010] In some embodiments, the concentration of the H2O2 solution is 30%.

[0011] In some embodiments, the first stirring time in step (1) is 10 min, and the continuous stirring time is 48 h.

[0012] In some embodiments, the mass-volume ratio of the blue Mo ink solution, potassium chloride and glucose in step (2) is 13 mL: 500 g: (0.3-0.9) g.

[0013] In other embodiments, the mass-volume ratio of the blue Mo ink solution, potassium chloride and carbon source is 13 mL: 500 g: 0.3 g, 13 mL: 500 g: 0.5 g, 13 mL: 500 g: 0.7 g or 13 mL: 500 g: 0.9 g, preferably 13 mL: 500 g: 0.5 g.

[0014] In some embodiments, the water bath temperature in step (2) is 70℃.

[0015] In some embodiments, the calcination temperature in step (3) is 900℃, the calcination time is 3 h, and the heating rate is 1℃ / min; the hydrogen-argon mixture is 95% Ar+5% H2.

[0016] The application also provides an organic hydrophobic group metal carbide coupling thin film prepared by the preparation method described in the above technical solution.

[0017] The application also provides an application of the organic hydrophobic group metal carbide coupling thin film described in the above technical solution in photocatalytic reduction of carbon dioxide.

[0018] In the efficient solar carbon dioxide reduction, visible light to near infrared (NIR) low-energy photons (more than 50% of solar energy) cannot excite the high-energy reaction required for the dissociation of the C=O bond in carbon dioxide. The present application uses a new method of often neglected photo-thermal (PTT) conversion to provide a 2D-2D carbon layer embedded Mo2C (Mo2C-C x ) MXene, molybdenum carbide (Mo2C) is a black two-dimensional nanomaterial (MXene) with a hexagonal crystal structure with strong intralayer covalent bonds and weak interlayer van der Waals interactions, high thermal conductivity (~48.4 W / m·K) and good mechanical stability. In addition, the broad spectrum of Mo2C light absorption, excellent thermal stability and high melting point (>2000℃) make it a major candidate for PTT conversion applications, by integrating Mo2C with carbon layers, taking advantage of the superior PTT conversion potential of carbon layers and the catalytic performance of Mo2C, to achieve efficient photocatalytic CO2 reduction efficiency. In the present application, the carbon layer and the subsequent 2D-2D embedded structure are formed in situ, showing a structure similar to graphene, which uses PTT conversion to effectively photocatalyze CO2 reduction using sunlight, significantly enhancing the near-infrared absorption in the range of 800-2000 nm and the corresponding PTT conversion.

[0019] Beneficial technical effects:

[0020] The preparation method provided by the present application is simple, and the synergistic effect of the catalytic properties of Mo2C and the PTT enhancement of the carbon layer makes the designed black 2D-2D carbon layer embedded Mo2C two-dimensional metal carbide catalyst have super strong absorption capacity for near-infrared light (NIR), which can efficiently utilize low-energy photons through photo-thermal conversion, and further significantly improve the CO2 reduction activity, realizing CO2 reduction in a wide wavelength range from ultraviolet to near-infrared light. This new technology provides a new direction for using low-frequency, low-energy photons to enhance the photocatalytic carbon dioxide reduction reaction. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 TEM photos of the catalysts obtained in Examples 1-4 and the original Mo2C catalyst, wherein (a) is a TEM photo of the original Mo2C catalyst, (b) is a TEM photo of the Mo2C-C 0.3 obtained in Example 1, (c) is a TEM photo of the Mo2C-C 0.5 obtained in Example 2, (d) is a TEM photo of the Mo2C-C 0.7 obtained in Example 3, and (e) is a TEM photo of the Mo2C-C 0.9 obtained in Example 4;

[0022] Figure 2 XRD patterns of the catalysts obtained in Examples 1-4 and the original Mo2C catalyst;

[0023] Figure 3 UV-vis-NIR DRS spectra of the catalysts obtained in Examples 1-4 and the original Mo2C catalyst;

[0024] Figure 4 Temperature comparison chart of the catalysts obtained in Examples 1-4 and the original Mo2C catalyst under the same irradiation conditions, using an infrared thermal imaging camera to compare the on and off light temperatures;

[0025] Figure 5 Yield chart of the catalysts obtained in Examples 1-4 and the original Mo2C catalyst under simulated sunlight Xe lamp irradiation for 5 hours to complete the photocatalytic reaction;

[0026] Figure 6 Mo2C-C catalyst obtained in Example 2 0.5 Yield chart under light and without light at different temperatures;

[0027] Figure 7 Mo2C-C catalyst obtained in Example 2 0.5 Long-term cycle experiment chart of the photocatalytic CO2 reduction;

[0028] Figure 8 Mo2C-C catalyst obtained in Example 2 0.5 Photocatalysis experiment chart in a concave mirror concentrating system with / without a cooling system, wherein (a) is a schematic diagram of the experimental device for photocatalysis in a concave mirror concentrating system without a cooling system, (b) is a schematic diagram of the experimental device for photocatalysis in a concave mirror concentrating system with a cooling system, (c) is a chart showing the difference in CO2 reduction performance of the Mo2C-C 0.5 catalyst and the original Mo2C catalyst under concentrated natural light, and (d) is a chart showing the CO2 reduction performance during a period of 2 months. DETAILED DESCRIPTION

[0029] In order to better understand the present application, the following examples further illustrate the content of the present application, but the content of the present application is not limited only to the following examples. In the following examples, the target product is marked as Mo2C-C x , and x represents the amount of glucose added corresponding to 0.1 g of Mo powder.

[0030] Example 1

[0031] A preparation method of a photocatalyst for efficient photo-thermal conversion reduction of CO2:

[0032] (1) 0.1 g of Mo powder was dispersed in 24 mL of ethanol, stirred for 10 min, and 0.75 mL of 30% H2O2 solution was slowly added, continuously stirred for 48 h, and a blue Mo ink solution was obtained;

[0033] (2) 13 mL of blue Mo ink solution from step (1) was injected into 500 g of potassium chloride by injection, followed by the addition of 0.3 g of glucose, and the mixture was stirred vigorously in a 70 °C water bath until dry;

[0034] (3) The dried mixture from step (2) was heated to 900 °C at a rate of 1 °C / min in a high-temperature tube furnace and held for 3 h under a gas condition of 5% H2+95% Ar, then cooled to room temperature, washed with deionized water, and filtered to remove residual potassium chloride, and dried to obtain the target product, labeled as Mo2C-C 0.3 .

[0035] Example 2

[0036] The same as Example 1, except that the amount of glucose added in step (2) was 0.5 g, and the resulting target product was labeled as Mo2C-C 0.5 .

[0037] Example 3

[0038] The same as Example 1, except that the amount of glucose added in step (2) was 0.7 g, and the resulting target product was labeled as Mo2C-C 0.7 .

[0039] Example 4

[0040] The same as Example 1, except that the amount of glucose added in step (2) was 0.9 g, and the resulting target product was labeled as Mo2C-C 0.9 .

[0041] Characterization tests

[0042] The catalysts obtained in Examples 1-4 were subjected to TEM characterization along with the original Mo2C catalyst (original Mo2C nanoplatelets commercially purchased from Aladdin Biochem Technology Co., Ltd. (China)), and the results are shown in Figure 1 Compared with the original Mo2C catalyst, the Mo2C-C x catalysts exhibited a porous 2D-2D intercalation structure. Increasing the amount of glucose resulted in an increase in carbon layer content and an increase in pore structure, producing surface pore structures of 100-200 nm.

[0043] The catalysts obtained in Examples 1-4 were subjected to XRD characterization along with the original Mo2C catalyst (original Mo2C nanoplatelets commercially purchased from Aladdin Biochem Technology Co., Ltd. (China)), and the results are shown in Figure 2 Compared with the original Mo2C catalyst, the Mo2C-C xThere was no significant difference in the Mo2C crystalline phase in the catalyst, however, as the carbon content increased, the carbon layer exhibited characteristic reduction graphene oxide (RGO) features, with an enhanced XRD diffraction peak at 2θ = 25°. RGO has a high thermal conductivity coefficient (46.1 W / m·K) and efficient PTT performance, Mo2C-C x This characteristic RGO feature of the catalyst enhances the Mo2C-C x The light absorption intensity of the catalyst in the near-infrared region (800-2000 nm).

[0044] Mo2C-C x The UV-vis-NIR DRS spectra of Mo2C and Mo2C-C Figure 3 catalysts are shown in Figure 2. It can be seen that Mo2C-C x has stronger light absorption intensity in the near-infrared region (800-2000 nm), and Mo2C-C 0.5 performs best.

[0045] Test Example

[0046] 1. Indoor photocatalytic CO2 reduction experiment:

[0047] CO2 photoreduction was carried out in a sealed 200 mL quartz reactor, with a 300 W xenon lamp (1000 mW·cm -2 ) as the white light source. 5 mg of Mo2C-C x catalyst was dispersed in 2 ml of deionized water, then the resulting mixture was deposited on a 1 cm x 2 cm quartz glass, and dried at 60°C, the dried catalyst was placed at the bottom of the quartz reactor, water vapor was introduced into the reactor together with carbon dioxide for 30 minutes to completely purify the air. The room temperature was maintained at 20-90°C by using a circulating water layer, or the temperature was not controlled under continuous light. The light intensity on the photocatalyst was measured to be 1000 mW·cm -2 by a full-automatic light power meter (CEL-NP2000-10A, China). After irradiation for 60 minutes, the gaseous products were analyzed by a gas chromatograph (GC-7920, China) equipped with a hydrogen flame ionization detector (FID).

[0048] The PTT conversion was directly observed by using an infrared imaging temperature-sensitive camera, and Figure 4 it was found that the average temperature of the light conversion to heat of the Mo2C-Cx catalyst embedded with carbon layers was 50-70°C higher than that of the original Mo2C (182.8°C) under the same white light irradiation (Xe lamp, 1000 mW / cm 2 ). The highest temperature (Tmax) of the best Mo2C-C 0.5 catalyst reached 256.6°C.

[0049] The improvement of PTT conversion rate is expected to significantly promote the photocatalytic reduction of CO2. Without controlling the temperature of the reaction system, Mo2C and different Mo2C-C x The comparison of the rate of gas production of the catalysts in 5h is shown in Figure 5 Figure 5 It can be seen that under the same xenon lamp light conditions, Mo2C-C 0.3 , Mo2C-C 0.5 , Mo2C-C 0.7 , Mo2C-C 0.9 The CO production rates of the catalysts are 41.6μmol·h -1 ·g -1 , 48.2μmol·h -1 ·g -1 , 32.4μmol·h -1 ·g -1 , 28.2μmol·h -1 ·g -1 , respectively, which is more than 20 times of the original Mo2C catalyst (2.3μmol·h -1 ·g -1 ). During the entire reaction process, the T max of the catalyst surface is maintained due to PTT conversion.

[0050] The long-term cycle experiment of CO2 reduction of Mo2C-C 0.5 catalyst is shown in Figure 7 It can be seen that after 50 hours of long-term operation, Mo2C-C 0.5 catalyst can still maintain catalytic stability and high catalytic efficiency close to the initial value.

[0051] 2. Natural sunlight driven photocatalytic CO2 reduction experiment:

[0052] The external concave mirror based solar light concentration system. 5mg of Mo2C-C 0.5 and Mo2C catalysts were dispersed in 2ml of deionized water, and then the obtained mixture was deposited on a 1cm×2cm quartz glass and dried at 60℃. The dried catalyst was placed at the bottom of the quartz reactor.

[0053] The photocatalytic reactor temperature was controlled at 20℃ by circulating water layer, or without temperature control under continuous light irradiation. The surface temperature of the catalyst was measured by infrared thermal imager (RX500). After 2 minutes of solar irradiation, the gas products were analyzed by gas chromatograph (GC-7920, China) equipped with hydrogen flame ionization detector (FID).

[0054] Figure 8 ​Fig. 1 is a schematic diagram of the experimental device for photocatalysis using a concave mirror light-concentrating system without cooling system. The inset shows the temperature of the central reactor during illumination (light on) and darkness (light off). The working temperature of Mo2C-C 0.5 reached 455.1°C; (b) a schematic diagram of the experimental device for photocatalysis using a concave mirror solar light-concentrating system, this time using a water circulation cooler as the cooling system; the inset shows the temperature of the central reactor during illumination (light on) and darkness (light off); after using the cooling system, the working temperature of Mo2C-C 0.5 remained above 45.8°C; (c) the difference in the performance of CO2 reduction under concentrated natural light between Mo2C-C 0.5 and the original Mo2C catalyst at different working temperatures; (d) the CO2 reduction performance during a period of 2 months, which is related to the measured focus intensity on the target Mo2C-C 0.5 catalyst. The STF conversion efficiency ranged from 0.0108% to 0.0143%, and STFavg= 0.0123%.

[0055] 3. The experiment of the prepared sample on the photo-thermal conversion carbon dioxide reduction:

[0056] The generated CO and CH4 were detected by online gas chromatography (GC-7920), with nitrogen as the carrier gas. Figure 6 The gas production rates of Mo2C-C 0.5 at different temperatures were compared, the thermal effect was illustrated, and the influence of photo-thermal conversion on improving the activity of carbon dioxide reduction was explained.

[0057] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. The application of an organic hydrophobic group metal carbide coupled thin film in the photocatalytic reduction of carbon dioxide, characterized in that, The method for preparing the organic hydrophobic group metal carbide coupled thin film includes the following steps: (1) Disperse Mo powder in ethanol, stir for the first time and slowly add H2O2 solution, then stir continuously to obtain blue Mo ink solution; (2) Inject the blue Mo ink solution obtained in step (1) into potassium chloride, then add glucose and stir the mixture vigorously in a water bath until dry; (3) The dried mixture from step (2) was calcined in a hydrogen-argon mixture atmosphere, cooled to room temperature, washed, and then grown in situ to obtain Mo2C-C. x Coupled film, where X corresponds to the mass of glucose added.

2. The application of the organic hydrophobic group metal carbide coupled film according to claim 1 in the photocatalytic reduction of carbon dioxide, characterized in that, The mass-to-volume ratio of Mo powder, ethanol, and H2O2 solution in step (1) is 0.1g:24mL:0.75mL.

3. The application of the organic hydrophobic group metal carbide coupled film according to claim 1 or 2 in the photocatalytic reduction of carbon dioxide, characterized in that, The concentration of the H2O2 solution is 30%.

4. The application of the organic hydrophobic group metal carbide coupled film according to claim 1 in the photocatalytic reduction of carbon dioxide, characterized in that, The first stirring time in step (1) is 10 min, and the continuous stirring time is 48 h.

5. The application of the organic hydrophobic group metal carbide coupled film according to claim 1 in the photocatalytic reduction of carbon dioxide, characterized in that, The mass-volume ratio of the blue Mo ink solution, potassium chloride and glucose in step (2) is 13 mL: 500 g: (0.3-0.9) g.

6. The application of the organic hydrophobic group metal carbide coupled film according to claim 5 in the photocatalytic reduction of carbon dioxide, characterized in that, The mass-to-volume ratio of the blue Mo ink solution, potassium chloride, and glucose is 13mL:500g:0.3g, 13mL:500g:0.5g, 13mL:500g:0.7g, or 13mL:500g:0.9g.

7. The application of the organic hydrophobic group metal carbide coupled film according to claim 1 in the photocatalytic reduction of carbon dioxide, characterized in that, The water bath temperature in step (2) is 70°C.

8. The application of the organic hydrophobic group metal carbide coupled film according to claim 1 in the photocatalytic reduction of carbon dioxide, characterized in that, The calcination temperature in step (3) is 900℃, the calcination time is 3h, and the heating rate is 1℃ / min; the hydrogen-argon mixture is 95%Ar+5%H2.

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