KOH-loaded molybdenum disulfide photo-thermal catalyst as well as preparation method and application thereof

Abstract

The invention discloses a KOH-loaded molybdenum disulfide photo-thermal catalyst and a preparation method and application thereof, and relates to the technical field of photo-thermal catalytic reduction of CO2. The preparation method specifically comprises the following steps that ammonium molybdate tetrahydrate and thiourea serve as raw materials to obtain a homogeneous solution, then hydrothermal treatment is conducted to obtain a mixed solution, and the mixed solution is dried to obtain the KOH-loaded molybdenum disulfide photo-thermal catalyst. And then carrying out centrifugal treatment, washing treatment and drying treatment, then carrying out primary calcination treatment to obtain molybdenum disulfide powder, and finally loading KOH to obtain the KOH-loaded molybdenum disulfide photo-thermal catalyst. According to the preparation method of the catalyst, MoS2 with unsaturated edge coordination serves as a supporting carrier, MoS2 is dominated and converted into a high-activity defect structure / alkaline basal plane from an inert basal plane by loading KOH, CO2 molecules are adsorbed more easily through the alkaline basal plane, an intermediate product is formed, and the phenomenon that the catalyst is inactivated due to sulfur oxidation loss in the catalysis process can be inhibited. Therefore, the photo-thermal catalyst has huge potential in the aspect of CO2 reduction.

Description

Technical Field

[0001] The present invention relates to the technical field of photothermal catalytic reduction of CO2, and in particular to a KOH-loaded molybdenum disulfide photothermal catalyst, a preparation method thereof, and applications thereof. Background Art

[0002] With the continuous increase in global energy demand and increasingly severe environmental challenges, the development of renewable energy and the reduction of carbon dioxide (CO2) emissions have become critical global issues. The traditional use of fossil fuels not only leads to greenhouse gas emissions but also contributes to a range of environmental problems, including global climate change and air pollution. Therefore, the search for sustainable energy alternatives and the efficient utilization of CO2 have become research priorities in recent years. However, due to the stable structure of CO2 and its difficulty in being activated to participate in reactions, these approaches have achieved limited success and fail to address the fundamental issues. In recent years, research on CO2 conversion technologies has increased significantly, with electrochemical reduction, thermal catalytic conversion, and photothermal catalysis being the most promising approaches. Among these technologies, photothermal catalysis has attracted considerable attention due to its unique advantages. This technology combines light and thermal energy to effectively promote electron transfer and reactant conversion during the catalytic reaction, thereby achieving efficient CO2 conversion. It converts the virtually unlimited solar energy in nature into usable chemical energy, enabling the conversion and utilization of CO2 without consuming fossil energy. The core of photothermal catalytic reactions lies in the selection and design of catalysts, whose performance directly affects reaction efficiency and product selectivity. Therefore, designing an efficient photothermal catalyst for CO2 reduction is crucial for achieving this goal.

[0003] Molybdenum disulfide (MoS2) is a metal sulfide widely used in thermal catalysis, often used in hydrogenation and deoxygenation reactions. MoS2 has a hexagonal layered structure, and the Mo atoms between the layers are in a fully saturated coordination state, that is, the Mo atoms are bonded to the three nearest S atoms, and the S atoms are bonded to the six surrounding Mo atoms, and these layers are held together by van der Waals forces. The atoms with fully saturated coordination on the basal plane of the MoS2 crystal are chemically inert, while a few edge sites become catalytically active sites due to their unsaturated coordination. Therefore, it is of great significance to activate the inert basal plane to improve the catalytic activity of MoS2. Therefore, it is urgent to provide a preparation method for improving the activity and selectivity of the catalyst for photothermal reduction of CO2. Summary of the Invention

[0004] In order to further improve the performance of MoS2 photothermal catalytic reduction of CO2, the present invention provides a KOH-loaded MoS2 photothermal catalyst prepared by KOH treatment, a preparation method thereof, and an application thereof in photothermal catalytic reduction of CO2.

[0005] The first aspect of the present invention provides a method for preparing a KOH-supported molybdenum disulfide photothermal catalyst, the preparation method specifically comprising the following steps: S1. Adding ammonium molybdate tetrahydrate and thiourea to deionized water and stirring to prepare a homogeneous solution A; S2, subjecting the homogeneous solution A obtained in step S1 to hydrothermal treatment to obtain a mixed solution B; S3, after centrifuging the mixed solution B obtained in step S2, the precipitate is washed and dried in sequence, and finally calcined to obtain molybdenum disulfide powder; S4. Add the molybdenum disulfide powder obtained in step S3 to deionized water, then dropwise add potassium hydroxide solution, stir and dry in sequence to obtain a black powder, and perform a secondary calcination on the black powder to obtain a KOH-loaded molybdenum disulfide photothermal catalyst.

[0006] Compared with the prior art, the present invention provides a simple method for synthesizing KOH-loaded MoS2 photothermal catalysts to achieve controllable synthesis of KOH anchored on the carrier using MoS2 as a carrier. Strong base solution KOH and edge-coordinated unsaturated MoS2 are used as KOH, + and the source of the support carrier, KOH can convert Mo into 6+ Restored to Mo 4+ , and prevent Mo 4+ further oxidation, thereby ensuring the stability of the active sites.

[0007] In one possible embodiment, in step S1, the molar ratio of ammonium molybdate tetrahydrate to thiourea is 1:(27-33).

[0008] Compared with the existing technology, this ratio precisely matches the sulfur source supply required to form the ideal MoS2 crystal structure, ensuring that the molybdenum atoms are fully sulfurized to build a stable layered framework, while avoiding excessive thiourea leading to the formation of impurities or unreacted residues; at the same time, this stoichiometric ratio is conducive to the formation of a uniform precursor solution during the hydrothermal process, laying the foundation for the subsequent acquisition of MoS2 nanosheets with high crystallinity, high specific surface area and fully exposed edge active sites, thereby synergistically improving the photothermal responsiveness and sulfur vacancy controllability of the final catalyst.

[0009] In a possible embodiment, in step S2, the specific parameters of the hydrothermal treatment are as follows: temperature of 200-220° C., and time of 5.5-6.5 h.

[0010] Compared with existing technologies, this temperature and time window synergistically optimizes the crystallinity and micromorphology of MoS2 - ensuring sufficient hydrothermal reaction kinetics to form a stable layered crystal structure, while avoiding nanosheet stacking or structural defects caused by excessive growth; at the same time, it precisely matches the precursor decomposition and self-assembly process to promote the directional growth of three-dimensional flower-like nanosheets, thereby maximizing the exposure of edge active sites and constructing efficient mass transfer channels, providing an ideal carrier substrate for subsequent sulfur vacancy construction and photothermal synergistic catalysis.

[0011] In a possible embodiment, in step S3, the parameters of the centrifugal treatment are as follows: a rotation speed of 450-600 rpm, and a time of 20-30 min.

[0012] Compared with existing technologies, this range precisely matches the sedimentation kinetics of molybdenum disulfide nanomaterials—a moderate rotation speed ensures efficient separation of solid-phase precipitation in hydrothermal products, avoiding impurity residues caused by low speed or structural damage to nanosheets caused by high speed; the synchronously optimized centrifugation time ensures sufficient phase separation while maximally retaining the open morphology and edge active site integrity of the three-dimensional flower-like nanosheets, constructing a high specific surface area, low-agglomeration carrier substrate for subsequent KOH modification, thereby synergistically improving the sulfur vacancy formation efficiency and catalytic activity stability.

[0013] In a possible embodiment, in step S3, the parameters of the drying process are as follows: temperature of 50-70° C., and time of 10-13 h.

[0014] Compared with the prior art, the present invention adopts the above-mentioned drying treatment parameters. The temperature and appropriate time synergistically ensure the physicochemical stability of the molybdenum disulfide nanostructure - the low temperature range (50-70°C) effectively removes residual solvents (water / ethanol) and avoids sulfur loss or nanosheet oxidation caused by high temperature; the synchronously optimized drying time (10-13h) ensures sufficient dehydration while minimizing the agglomeration or microcracks of the nanosheets caused by rapid shrinkage, thereby maintaining the open pore structure and edge active site integrity of the high specific surface area carrier substrate, providing an ideal active site substrate for the efficient construction of sulfur vacancies in subsequent KOH modification and photothermal catalytic interface reactions.

[0015] In one possible embodiment, in step S3, a calcination treatment is performed in a tube furnace, and the parameters of the calcination treatment are as follows: heating to 200-400°C at a heating rate of 5-10°C / min for 2-2.5 hours, and nitrogen is continuously introduced during the calcination treatment.

[0016] Compared with existing technologies, this gradient temperature and precise duration synergistically optimize the lattice activation and defect control of MoS2 - the low temperature zone (starting from 200 ° C) effectively removes residual impurities and avoids high-temperature sulfur loss, and the high temperature end (up to 400 ° C) fully activates the basal plane atomic bonds without destroying the layered framework; the simultaneous introduction of nitrogen creates an oxygen-deficient environment, accurately inhibits sulfur oxidation and stabilizes Mo 4+ valence state, thereby directionally constructing high-concentration sulfur vacancies and maintaining the integrity of the edge unsaturated coordination structure; at the same time, a moderate calcination time (2-2.5 h) under a nitrogen atmosphere ensures that the crystal reconstruction is fully completed, laying a low defect energy barrier carrier foundation for the subsequent KOH insertion interlayer amplification of the active interface (K-Mo-S structure), and ultimately synergistically improving the electron transfer efficiency and CO2 reduction stability of the photothermal catalyst.

[0017] In a possible embodiment, in step S4, the mass ratio of potassium hydroxide in the potassium hydroxide solution to molybdenum disulfide powder is (0.08-0.12):1.

[0018] Compared with the prior art, the advantages of using potassium hydroxide in the present invention are: 1. The strong alkalinity of KOH promotes the activation of CO2. CO2 is an acidic gas, and strong bases (such as KOH) are more likely to interact with it: CO2 chemical adsorption is enhanced. The OH provided by KOH - Can directly react with CO2 to form carbonates (such as potassium carbonate) or formate (HCOO - ), lowering the energy barrier for CO2 activation. Other potassium salts (such as KCl and KNO3) lack strong basic sites and have weaker CO2 adsorption capacity. They promote C=O bond cleavage. In hydrogenation reactions (such as the reduction of CO2 to CO or CH4), the basic sites of KOH polarize the C=O bond, making it more susceptible to cleavage.

[0019] 2. Synergistic effect of KOH and MoS2: MoS2 is a typical transition metal sulfide, and its catalytic performance depends on the Mo-S active sites at the edge. The introduction of KOH can optimize these sites and regulate the electronic structure of MoS2: K + The electron donor effect can increase the electron density of the MoS2 conduction band and promote the reduction of CO2 (such as CO2+e - →CO2 - ). Other potassium salts (such as K2SO4) cannot effectively tune the electronic properties of MoS2.

[0020] 3. Formation of sulfur vacancies (S-vacancy): During high-temperature treatment, KOH reacts with sulfur atoms on the MoS2 surface to generate K2S and leave sulfur vacancies. These vacancies are key sites for CO2 adsorption and activation. Neutral potassium salts (such as KCl) have difficulty in inducing the formation of sulfur vacancies.

[0021] 4. Decomposition of potassium salt and active phase to form KOH High temperature decomposition: Under the reaction conditions, KOH partially decomposes into K2O or K + These species interact with MoS2 to form highly active interfaces (such as K-Mo-OS structures). However, salts such as potassium carbonate have high decomposition temperatures and are difficult to release active components under mild conditions.

[0022] In one possible embodiment, in step S4, the secondary calcination treatment is performed in a tube furnace, and the parameters of the secondary calcination treatment are as follows: heating to 250-350°C at a heating rate of 5-10°C / min for 2-2.5 hours in a nitrogen atmosphere.

[0023] The second object of the present invention is to provide a KOH-loaded molybdenum disulfide photothermal catalyst prepared by the above preparation method.

[0024] Compared with the existing technology, the present invention adjusts the atomic configuration by loading KOH, and constructs a highly efficient insoluble catalyst that can be applied to the photothermal catalytic reduction of CO2. It transforms MoS2 from an inert basal plane-dominated structure to a highly active defect structure. After loading KOH, a K-Mo-S mixed interface structure is formed, and K + Inserted between MoS2 layers, the interlayer spacing is expanded, and the embedded K + It can compensate for the negative charge of sulfur vacancies, reduce the defect formation energy, and promote the formation of more sulfur vacancies. + The catalyst synergistically optimizes CO adsorption and activation with sulfur vacancies and promotes the adsorption and conversion of intermediate carboxyl groups and carbon monoxide, surpassing edge-coordinate-unsaturated MoS2 in selectivity and activity in photothermal CO reduction reactions. Compared to MoS2, the KOH loading in the catalyst of this invention increases sulfur vacancy formation without affecting the original unsaturated coordination state at the edge.

[0025] The third object of the present invention is to provide the application of the KOH-loaded molybdenum disulfide photothermal catalyst in the field of photocatalytic CO2 reduction.

[0026] Compared with the prior art, the preparation method of the present invention uses MoS2 as a carrier and adds KOH during the synthesis process to construct a photothermal catalyst with an alkaline basal plane, which makes it easier to adsorb CO2 molecules to form an intermediate product (HCO3 - ), effectively improving reduction efficiency. MoS2 possesses inherent advantages such as multi-electron transfer, excellent light and heat absorption, and unsaturated coordination at its edges. Furthermore, KOH loading increases the interlayer spacing of MoS2, reduces stacking layers, and exposes more active sites. This also inhibits catalyst deactivation due to sulfur oxidation during the catalytic process. Therefore, KOH-loaded MoS2 photothermal catalysts hold great potential for CO2 reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The X-ray diffraction comparison patterns of 10% KOH-MoS2 prepared in Example 1 and MoS2 prepared in Comparative Example 1; Figure 2 Scanning electron microscope images of 10% KOH-MoS2 prepared in Example 1 and MoS2 prepared in Comparative Example 1; Figure 3 X-ray photoelectron spectra of 10% KOH-MoS2 prepared in Example 1 and MoS2 prepared in Comparative Example 1; Figure 4 The performance comparison chart of the photothermal catalysts prepared in Comparative Example 1 (Material A), Example 1 (Material B), Comparative Example 2 (Material C), Comparative Example 3 (Material D), and Comparative Example 4 (Material E) is shown; Figure 5 The performance comparison chart of the photothermal catalysts prepared in Example 1 (Material B), Comparative Example 5 (Material F), Comparative Example 6 (Material G), Comparative Example 7 (Material H), Comparative Example 8 (Material I), and Comparative Example 9 (Material J) are respectively shown. DETAILED DESCRIPTION

[0028] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only intended to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter ranges described in the present invention. Reasonable variations derived therefrom are still within the scope of protection of the claims of the present invention.

[0029] It should be noted that the endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0030] Unless otherwise defined, all terms, symbols and other scientific terms used herein are intended to have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. In some cases, terms with conventional meanings are defined herein for the purpose of clarification or ease of reference, and such definitions herein should not be construed as indicating significant differences from conventional understandings in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents and instruments was carried out in accordance with the protocols and parameters given by the manufacturers.

[0031] In the present invention, the photothermal reduction of CO2 was performed in a micro-photothermal catalytic microreactor system (Beijing Zhongjiao Jinyuan CEL-GPPCM). A 300W xenon lamp (PLS-SXE300+) was used as the light source, and the product was detected by gas analysis using an Agilent online gas chromatograph.

[0032] Gas chromatography analysis conditions: An Agilent GC-8860 online analytical gas chromatograph was equipped with a hydrogen ion flame detector (FID) and a thermal conductivity detector (TCD) to detect CH4 and CO generated by the reaction.

[0033] It is worth mentioning that in the following embodiments, since CO and CH4 are mainly generated in the CO2 reduction process, there is fierce competition between the generation of CH4 and CO, resulting in reduced selectivity, so the target product is CO.

[0034] The specific embodiment of the present invention provides a KOH-loaded molybdenum disulfide photothermal catalyst and its preparation method and application, wherein the preparation method of the molybdenum disulfide photothermal catalyst specifically comprises the following steps: S1. Adding ammonium molybdate tetrahydrate and thiourea to deionized water and stirring to prepare a homogeneous solution A, wherein the molar ratio of ammonium molybdate tetrahydrate to thiourea is 1:(27-33), wherein the stirring treatment may be a magnetic stirring treatment, and the time is about 20-30 minutes; S2. The homogeneous solution A obtained in step S1 is subjected to hydrothermal treatment to obtain a mixed solution B. The specific parameters of the hydrothermal treatment are as follows: temperature of 200-220° C., time of 5.5-6.5 h; S3. After centrifuging the mixed solution B obtained in step S2, the precipitate is washed and dried in sequence, and finally subjected to a calcination treatment to obtain molybdenum disulfide powder, wherein the parameters of the centrifugation treatment are as follows: a rotation speed of 450-600 rpm and a time of 20-30 min; the parameters of the drying treatment are as follows: a temperature of 50-70° C. and a time of 10-13 h; the primary calcination treatment is carried out in a tube furnace, and the parameters of the primary calcination treatment are as follows: heating to 200-400° C. at a heating rate of 5-10° C. / min and a time of 2-2.5 h, and nitrogen is continuously introduced during the calcination treatment; S4. The molybdenum disulfide powder obtained in step S3 is added to deionized water, and then a potassium hydroxide solution is added dropwise, wherein the mass ratio of potassium hydroxide in the potassium hydroxide solution to the molybdenum disulfide powder is (0.08-0.12): 1, and then stirred and dried in sequence to obtain a black powder, and the black powder is subjected to a secondary calcination treatment to obtain a KOH-loaded molybdenum disulfide photothermal catalyst, the secondary calcination treatment is carried out in a tubular furnace, and the parameters of the secondary calcination treatment are as follows: the temperature is raised to 250-350 ° C at a heating rate of 5-10 ° C / min for 2-2.5 h, and the atmosphere is nitrogen.

[0035] In the specific preparation process, in step S3, the specific operation of the washing treatment is: washing with deionized water and 95% ethanol solution in sequence, and the number of washing times is at least 3 times.

[0036] In step S4, the parameters of the drying process may be the same as those in step S3, ie, the temperature is 50-70° C., and the time is 10-13 h.

[0037] The KOH-loaded molybdenum disulfide photothermal catalyst prepared by the present invention can be used in the field of photocatalytic CO2 reduction.

[0038] Example 1

[0039] This embodiment provides a KOH-supported molybdenum disulfide photothermal catalyst, which is prepared by the following preparation method: S1. Add 0.83 g of ammonium molybdate tetrahydrate and 1.52 g of thiourea to 24 ml of deionized water and stir magnetically for 30 min to form a homogeneous solution to obtain solution A. S2. Pour solution A prepared in step S1 into a 50 ml reactor and hydroheat at 210°C for 6 h to obtain a mixed solution B; S3. Centrifuge the mixed solution B at 450 rpm for 20 min. Wash the resulting black precipitate three times with deionized water and 95% ethanol, then dry it at 60 °C for 12 h. Grind the dried sample into a black powder. Take 200 mg of the black powder and centrifuge it at 5 °C·min in a N2 atmosphere. -1 The mixture was heated to 300 °C at a rate of 100 °C and calcined at this high temperature for 2 h. After cooling to room temperature, black powder MoS2 was obtained. S4. Take 100 mg of the black powder MoS2 prepared in step S3 and disperse it in 10 ml of deionized water. Stir magnetically to disperse it evenly. Add 5 ml of potassium hydroxide solution (0.002 g ml -1 ), after magnetic stirring for 10 min, the mixture was heated at 600 r·min at 60 °C. -1The black powder A was stirred and dried at a rate of 5 ℃·min under N2 atmosphere. -1 The material was heated to 300 °C at a rate of 100 °C and calcined at this high temperature for 2 h. After cooling to room temperature, a black powder was obtained, named 10% KOH-MoS2, and marked as material B.

[0040] Example 2

[0041] This embodiment provides a KOH-supported molybdenum disulfide photothermal catalyst, which is prepared by the following preparation method: S1. Add 0.83 g of ammonium molybdate tetrahydrate and 1.68 g of thiourea to 24 ml of deionized water and stir magnetically for 20 min to form a homogeneous solution to obtain solution A. S2. Pour solution A obtained in step S1 into a 50 ml reactor and hydroheat at 200°C for 5.5 h to obtain a mixed solution B; S3. Centrifuge the mixed solution B at 500 rpm for 25 min. Wash the resulting black precipitate three times with deionized water and 95% ethanol, then dry it at 50 °C for 13 h. Grind the dried sample into a black powder. Take 200 mg of the black powder and centrifuge it at 8 °C min-1 in a N2 atmosphere. -1 The mixture was heated to 200 °C at a rate of 100 °C and calcined at this high temperature for 2.2 h. After cooling to room temperature, black powder MoS2 was obtained. S4. Take 100 mg of the black powder MoS2 prepared in step S3 and disperse it in 10 ml of deionized water. Stir magnetically to disperse it evenly. Add 6 ml of potassium hydroxide solution (0.002 g ml -1 ), after magnetic stirring for 10 min, the -1 The black powder A was stirred and dried at a rate of 8 ° C·min under N2 atmosphere. -1 The mixture was heated to 250°C at a rate of 1000 ℃ and calcined at this high temperature for 2 hours. After cooling to room temperature, a black powder was obtained.

[0042] Example 3

[0043] This embodiment provides a KOH-supported molybdenum disulfide photothermal catalyst, which is prepared by the following preparation method: S1. Add 0.83 g of ammonium molybdate tetrahydrate and 1.52 g of thiourea to 24 ml of deionized water and stir magnetically for 25 min to form a homogeneous solution to obtain solution A. S2. Pour solution A obtained in step S1 into a 50 ml reactor and hydroheat at 220°C for 6.5 h to obtain a mixed solution B; S3. Centrifuge the mixed solution B at 600 rpm for 30 min. Wash the resulting black precipitate three times with deionized water and 95% ethanol, then dry it at 70 °C for 10 h. Grind the dried sample into a black powder. Take 200 mg of the black powder and centrifuge it at 10 °C min-1 in a N2 atmosphere. -1 The mixture was heated to 400 °C at a rate of 100 °C and calcined at this high temperature for 2.5 h. After cooling to room temperature, black powder MoS2 was obtained. S4. Take 100 mg of the black powder MoS2 prepared in step S3 and disperse it in 10 ml of deionized water. Stir magnetically to disperse it evenly. Add 4 ml of potassium hydroxide solution (0.002 g ml -1 ), after magnetic stirring for 10 min, the -1 The black powder A was stirred and dried at a rate of 10 ℃·min under N2 atmosphere. -1 The mixture was heated to 350 °C at a rate of 0.5 ℃ and calcined at this high temperature for 2.5 h. After cooling to room temperature, a black powder was obtained.

[0044] Comparative Example 1 This comparative example provides a molybdenum disulfide photocatalyst. The only difference from Example 1 is that step S4 is not performed in this comparative example. The specific preparation steps are as follows: S1. Add 0.83 g of ammonium molybdate tetrahydrate and 1.52 g of thiourea to 24 ml of deionized water and stir magnetically for 30 min to form a homogeneous solution to obtain solution A. S2. Pour solution A prepared in step S1 into a 50 ml reactor and hydroheat at 210°C for 6 h to obtain a mixed solution B; S3. Centrifuge the mixed solution B at 450 rpm for 20 min. Wash the resulting black precipitate three times with deionized water and 95% ethanol, then dry it at 60 °C for 12 h. Grind the dried sample into a black powder. Take 200 mg of the black powder and centrifuge it at 5 °C·min in a N2 atmosphere. -1 The material was heated to 300 °C at a rate of 100 °C and calcined at this high temperature for 2 h. After cooling to room temperature, black powder MoS2 was obtained, which was marked as material A.

[0045] Comparative Example 2 This comparative example provides a KOH-loaded molybdenum disulfide photothermal catalyst, marked as material C. The only difference from Example 1 is that in step S4 of this comparative example, the mass of KOH is 2 mg. The rest is the same as Example 1 and will not be repeated here.

[0046] Comparative Example 3 This comparative example provides a KOH-loaded molybdenum disulfide photothermal catalyst, marked as material D. The only difference from Example 1 is that in step S4 of this comparative example, the mass of KOH is 5 mg. The rest is the same as Example 1 and will not be repeated here.

[0047] Comparative Example 4 This comparative example provides a KOH-loaded molybdenum disulfide photothermal catalyst, marked as Material E. The only difference from Example 1 is that in step S4 of this comparative example, the mass of KOH is 15 mg. The rest is the same as Example 1 and will not be repeated here.

[0048] Comparative Example 5 This comparative example provides a KOH-loaded molybdenum disulfide photothermal catalyst, labeled as Material F. The only difference from Example 1 is that in step S4 of this comparative example, the calcination temperature is 500° C. The rest is the same as Example 1 and will not be repeated here.

[0049] Comparative Example 6 This comparative example provides a KOH-loaded molybdenum disulfide photothermal catalyst, labeled as Material G. The only difference from Example 1 is that in step S4 of this comparative example, the calcination temperature is 400° C. The rest is the same as Example 1 and will not be repeated here.

[0050] Comparative Example 7 This comparative example provides a KOH-loaded molybdenum disulfide photothermal catalyst, labeled as Material H. The only difference from Example 1 is that in step S4 of this comparative example, the calcination temperature is 380° C. The rest is the same as Example 1 and will not be repeated here.

[0051] Comparative Example 8 This comparative example provides a KOH-loaded molybdenum disulfide photothermal catalyst, labeled as Material I. The only difference from Example 1 is that in step S4 of this comparative example, the calcination temperature is 230° C. The rest is the same as Example 1 and will not be repeated here.

[0052] Comparative Example 9 This comparative example provides a KOH-loaded molybdenum disulfide photothermal catalyst, labeled as Material J. The only difference from Example 1 is that in step S4 of this comparative example, the calcination temperature is 200° C. The rest is the same as Example 1 and will not be repeated here.

[0053] Performance testing: The materials obtained in Example 1 and Comparative Example 1 were subjected to a photothermal catalytic reduction of CO2 activity experiment under visible light irradiation. The specific implementation steps are as follows: The entire reaction is carried out in a gas-solid reaction system. In a typical procedure, 0.2 g of quartz sand is placed in a quartz glass tube, followed by 20 mg of the prepared material B or material A. The quartz tube is then secured in the reactor and argon is introduced until the pressure reaches 100 kPa. This pressure is maintained for 10-15 minutes before being released. A mixture of CO2 and H2 is then introduced, and a xenon lamp is turned on. The products, CO and CH4, are monitored hourly by an online gas chromatograph.

[0054] The present invention uses MoS2 as a precursor to explore the photothermal catalytic performance of KOH loaded with different contents to obtain the optimal photothermal catalytic CO2 performance.

[0055] Figure 1 The X-ray diffraction (XRD) comparison patterns of 10% KOH-MoS2 prepared in Example 1 and MoS2 prepared in Comparative Example 1. The results show that the XRD characteristic peak position of 10% KOH-MoS2 prepared in Example 1 remains basically unchanged, which indicates that the catalyst after KOH loading can still maintain a good crystal shape, and the characteristic peak intensity of the catalyst after KOH loading is higher than that of the pure MoS2 catalyst, which indicates that due to the edge effect, 10% KOH-MoS2 prepared in Example 1 is conducive to the enrichment of active sites. In addition, the diffraction peaks of the (002) plane of MoS2 prepared in Comparative Example 1 and 10% KOH-MoS2 prepared in Example 1 are slightly shifted, which may be due to the fact that K + The lattice distortion is caused by replacing some atoms in MoS2 or entering the interstitial sites, indicating that defects appear on the inert basal plane.

[0056] Figure 2 The scanning electron microscope (SEM) images of 10% KOH-MoS2 prepared in Example 1 and MoS2 prepared in Comparative Example 1, wherein (a) is the scanning electron microscope image of MoS2 prepared in Comparative Example 1, and (b) is the scanning electron microscope image of 10% KOH-MoS2 prepared in Example 1; Figure 2 Scanning electron micrographs of the MoS2 catalyst before and after KOH loading reveal a three-dimensional, flower-like nanosheet structure. These nanosheets are interconnected, forming a three-dimensional, flower-like network. This overcomes the disordered stacking of MoS2 layers by exposing numerous active edge sites and increasing the specific surface area, thereby reducing diffusion pathways for reactants and surface charges.

[0057] Figure 3X-ray photoelectron spectroscopy (XPS) of 10% KOH-MoS2 prepared in Example 1 and MoS2 prepared in Comparative Example 1. All representative spectra are shown after calibration with the standard C 1s peak at 284.6 eV for Mo 3d and S 2s. The fitting principles include three aspects: (a) the spin-orbit splitting energy is fixed; (b) each peak is aligned with its full width at half maximum; and (c) the peak area ratio of each doublet is determined based on the spin-state degeneracy. Based on these fitting criteria, the elemental coordination structure of MoS2 is clearly described.

[0058] Mo 3d 5 / 2 and Mo 3d 3 / 2 The two characteristic peaks at 229.7 and 232.8 eV represent Mo 4+ Small Mo atoms were observed at 233.0 and 236.0 eV. 6+ Peak. Mo after loading modified KOH 4+ The peak positions of S 2p at 162.6 and 163.7 eV are attributed to unsaturated S 2- or terminal S2 2- S 2p 3 / 2 and S 2p 1 / 2 orbital, the peak position shifted to the low binding energy direction after KOH loading, and was 162.0 and 163.2 eV. This indicates that part of S 2- and S2 2- It moves out from the inert basal plane to form an S vacancy.

[0059] Figure 4 The performance comparison chart of the photothermal catalysts prepared in Comparative Example 1 (Material A), Example 1 (Material B), Comparative Example 2 (Material C), Comparative Example 3 (Material D), and Comparative Example 4 (Material E) is shown. Figure 4 It can be seen that the CO evolution rate in the photothermal catalytic CO reduction reaction of the 10% KOH-MoS2 catalyst prepared in Example 1 of the present invention is 4.25 mmol g -1 h -1 The selectivity is as high as 99.8%, which is much higher than the activity and selectivity of pure MoS2 photocatalytic CO2 reduction (0.59 mmol g -1 h -1 This further demonstrates that the 10% KOH-MoS2 photothermal catalyst prepared using the preparation parameters of the present invention can achieve efficient photocatalytic CO2 reduction.

[0060] Figure 5The performance comparison chart of the photothermal catalysts prepared in Example 1 (Material B), Comparative Example 5 (Material F), Comparative Example 6 (Material G), Comparative Example 7 (Material H), Comparative Example 8 (Material I), and Comparative Example 9 (Material J) is shown. Figure 5 It can be seen that the CO evolution rate in the photothermal catalytic CO reduction reaction of the 10% KOH-MoS2 catalyst prepared in Example 1 of the present invention is 4.25 mmol g -1 h -1 The selectivity is as high as 99.8%, which is higher than the catalytic activity of 10% KOH-MoS2 photothermal catalyst prepared at other calcination temperatures (the highest performance of other catalysts is 4.11 mmol g -1 h -1 and 98.3% selectivity).

[0061] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for preparing a KOH-supported molybdenum disulfide photothermal catalyst, characterized in that: The preparation method specifically comprises the following steps: S1. Adding ammonium molybdate tetrahydrate and thiourea to deionized water and stirring to prepare a homogeneous solution A; S2, subjecting the homogeneous solution A obtained in step S1 to hydrothermal treatment to obtain a mixed solution B; S3, after centrifuging the mixed solution B obtained in step S2, the precipitate is washed and dried in sequence, and finally calcined to obtain molybdenum disulfide powder; S4. Add the molybdenum disulfide powder obtained in step S3 to deionized water, then dropwise add potassium hydroxide solution, stir and dry in sequence to obtain a black powder, and perform a secondary calcination on the black powder to obtain a KOH-loaded molybdenum disulfide photothermal catalyst.

2. The preparation method according to claim 1, wherein In step S1, the molar ratio of ammonium molybdate tetrahydrate to thiourea is 1:(27-33).

3. The preparation method according to claim 1, wherein In step S2, the specific parameters of the hydrothermal treatment are as follows: temperature is 200-220° C., and time is 5.5-6.5 h.

4. The preparation method according to claim 1, wherein In step S3, the parameters of the centrifugal treatment are as follows: a rotation speed of 450-600 rpm and a time of 20-30 min.

5. The preparation method according to claim 1, wherein In step S3, the parameters of the drying process are as follows: temperature is 50-70° C., and time is 10-13 h.

6. The preparation method according to claim 1, wherein In step S3, a primary calcination treatment is performed in a tube furnace, and the parameters of the primary calcination treatment are as follows: heating to 200-400°C at a heating rate of 5-10°C / min for 2-2.5 hours, and nitrogen is continuously introduced during the calcination treatment.

7. The preparation method according to claim 1, wherein In step S4, the mass ratio of KOH in the potassium hydroxide solution to the molybdenum disulfide powder is (0.08-0.12):

1.

8. The preparation method according to claim 1, wherein In step S4, the secondary calcination treatment is performed in a tube furnace, and the parameters of the secondary calcination treatment are as follows: heating to 250-350° C. at a heating rate of 5-10° C. / min for 2-2.5 h in a nitrogen atmosphere.

9. A KOH-supported molybdenum disulfide photothermal catalyst, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the KOH-supported molybdenum disulfide photothermal catalyst according to claim 9 in the field of photocatalytic CO2 reduction.

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