CdS / MoS2 / MnO2 photocatalyst and preparation method thereof

Abstract

The invention discloses a CdS / MoS2 / MnO2 photocatalyst and a preparation method thereof, MoS2 reduction sites and MnO2 oxidation sites are respectively constructed on the surface of a CdS nanorod through a chemical occupation strategy and a photodeposition method, double active sites which are spatially separated and uniformly distributed are realized, and the migration distance of carriers to the reaction active sites is remarkably shortened, so that the carrier separation efficiency is improved; the H2S odor removal rate of the catalyst reaches 90% or above after the catalyst is irradiated by 365 nm and 254 nm ultraviolet light, and the catalyst is excellent in cycling stability. The invention provides an efficient and low-cost solution for effectively removing the gaseous pollutant H2S in the environment.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, and relates to a CdS / MoS2 / MnO2 photocatalyst and its preparation method. Background Technology

[0002] With the booming development of the livestock and poultry farming industry, a serious environmental problem has gradually emerged – the concentration of important odorous gases produced by animal metabolism, such as NH3 and H2S, in the environment has risen sharply. Among them, H2S, as one of the seven major environmental hazards, is particularly harmful. It has a strong pungent odor, is widely distributed, and poses a serious threat to the ecological environment and human health. Long-term exposure to high concentrations of H2S can cause respiratory diseases and even lead to poisoning and death. This has become a key factor restricting the sustainable development of the livestock and poultry industry. Therefore, it is imperative to explore effective methods to reduce H2S concentrations.

[0003] Among numerous technologies for treating H2S, photocatalysis has become a research hotspot in the field of H2S degradation due to its significant advantages, including ease of operation, non-toxicity, and avoidance of secondary pollution. Many researchers are focusing their attention on this area, hoping to achieve efficient H2S treatment through photocatalysis and provide a feasible solution to the odor problem in livestock and poultry farming.

[0004] However, current photocatalytic technology still faces many challenges in treating H2S. On the one hand, most semiconductor materials developed so far have relatively low H2S removal rates, making it difficult to meet the demands for efficient degradation in practical applications. On the other hand, the catalysts themselves suffer from photocorrosion, easily deactivating under light conditions, leading to a significant decrease in catalytic performance and a shortened lifespan, resulting in a large gap between photocatalytic technology and practical applications. Further research has revealed that the mismatch between electron and hole consumption rates is a key factor leading to poor photocatalytic activity and stability. To address this issue, loading suitable co-catalysts onto the catalyst surface is considered an effective approach, as it can promote carrier separation and form highly active reaction sites, thereby facilitating the catalytic reaction. However, in traditional catalyst systems, the co-catalyst loading process faces numerous control challenges. Due to improper loading process control, the distribution of catalytic active sites is uneven, and recombination due to localized carrier excess still exists at the microscopic level, reducing photocatalytic efficiency. Simultaneously, the loose bond between the co-catalyst and the catalyst hinders the smooth migration of carriers to the active sites, further affecting the catalytic reaction efficiency. Related research findings have been published in authoritative journals such as *Chem. Eng. J.*, *Adv. Funct. Mater.*, *Applied Catalysts S.B., Environ.*, *J. Catal.*, and *J. Struct. Chem.*. This demonstrates that developing catalysts with high H2S degradation efficiency and good cycle stability remains a key challenge to be overcome and is crucial for promoting the practical application of photocatalysis technology in H2S treatment. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a CdS / MoS2 / MnO2 photocatalyst and its preparation method, thereby solving the technical problems in the prior art where semiconductor materials used for H2S removal suffer from mismatched electron and hole consumption rates, low H2S removal rate, and easy photo-corrosion deactivation of the catalyst. In addition, traditional catalyst systems suffer from uneven distribution of active sites and loose bonding between the co-catalyst and the catalyst when loaded with a co-catalyst, resulting in low catalytic efficiency, affected reaction efficiency, and difficulty in achieving efficient degradation.

[0006] This invention is achieved through the following technical solution: A method for preparing a CdS / MoS2 / MnO2 photocatalyst includes the following steps: S1: Add cadmium chloride to ethylenediamine, sonicate until completely dissolved, then add thiourea, stir and mix evenly, and then carry out hydrothermal reaction on the mixture to obtain CdS nanorod suspension; S2: Thioacetamide and sodium molybdate are dispersed in ethylenediaminetetraacetic acid, and then the CdS nanorod suspension is added to carry out a hydrothermal reaction to obtain MoS2 modified CdS nanorods. S3: Add the MoS2-modified CdS nanorods to water, then add manganese acetate under light-protected conditions, stir evenly under light-protected conditions, and place the mixture under a xenon lamp for photodeposition reaction. After the reaction is completed, the CdS / MoS2 / MnO2 photocatalyst is obtained.

[0007] Preferably, in step S1, the ratio of cadmium chloride, thiourea, and ethylenediamine is (2.5~3.5) g:(2.5~3.3) g:(80~100) mL.

[0008] Preferably, in step S1, the hydrothermal reaction temperature is 160~200℃ and the time is 30~42 h.

[0009] Preferably, in step S2, the ratio of thioacetamide, sodium molybdate, and CdS nanorod suspension is (70~90) mg:(15~25) mg:(0.8~3.2) mL, and the concentration of the CdS nanorod suspension is 25~35 mg / mL.

[0010] Preferably, in step S2, the ratio of thioacetamide, sodium molybdate, and ethylenediaminetetraacetic acid is (70~90) mg:(15~25) mg:(80~100) mL.

[0011] Preferably, in step S2, the hydrothermal reaction temperature is 150~210℃ and the time is 13~19 h.

[0012] Preferably, in step S3, the mass ratio of MoS2-modified CdS nanorods to manganese acetate is (25~35):(5~15).

[0013] Preferably, in step S3, during the photodeposition reaction, the irradiation power of the xenon lamp is 200~250 W, the wavelength is 320~780 nm, and the irradiation time is 40~50 min.

[0014] A CdS / MoS2 / MnO2 photocatalyst was prepared by the method described above.

[0015] The above-mentioned CdS / MoS2 / MnO2 photocatalyst is used in photocatalytic H2S removal.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses a method for preparing a CdS / MoS2 / MnO2 photocatalyst. The method utilizes MoS2 as an electron trapper and MnO2 as a hole trapper, constructing a dual-active-site heterojunction system on the surface of CdS nanorods via hydrothermal reaction and photodeposition. MoS2 and MnO2 possess strong electron and hole trapping capabilities, respectively. Their growth at different spatial positions on the CdS surface facilitates the formation of a large-area, non-uniform local electric field that induces rapid separation of electrons and holes, effectively suppressing charge recombination. Furthermore, the strong interaction between CdS and MnO2 alters the surface electron coordination environment, promoting charge transfer imbalance and further inhibiting recombination. In an H2S atmosphere, holes accumulated on MnO2 rapidly convert OH⁻ into hydroxyl radicals, while electrons accumulated on MoS2 convert oxygen into superoxide radicals. The synergistic effect of these two reactive oxygen species significantly enhances H2S degradation efficiency, achieving efficient utilization of photogenerated carriers. To address the problem of uneven distribution of active sites in traditional catalysts, this invention employs a stepwise construction strategy to ensure the uniform distribution of the MoS2 coating layer and MnO2 nanoparticles on the CdS surface, forming spatially separated dual active sites. This allows photogenerated electrons and holes to be directionally captured by MoS2 and MnO2, respectively, avoiding overloading of a single active site and enhancing structural stability through a tight heterojunction interface, effectively suppressing photocorrosion. Experiments show that this catalyst achieves a 94.7% H2S degradation rate after 2 hours of 365nm UV irradiation, without requiring a noble metal co-catalyst. This is attributed to the synergistic effect of MoS2 and MnO2, which not only broadens the light absorption range of CdS but also achieves efficient electron-hole separation and utilization through uniformly distributed active sites, thus solving the problems of low catalytic efficiency and poor stability in traditional systems.

[0017] In S3, manganese acetate provides the manganese source for the generation of MnO2, and oxygen is obtained from water. Under light conditions, the holes on the CdS surface oxidize manganese acetate to MnO2. In this experiment, the amount of manganese source added is sufficient, and MnO2 can be continuously generated during the light process. Therefore, the light exposure time has a direct impact on the amount of MnO2 generated.

[0018] Furthermore, in step S1, the hydrothermal reaction temperature is 160~200℃ and the time is 30~42 h. In this step, the hydrothermal reaction temperature and reaction time have a significant impact on the crystallinity and size of CdS nanorods. Furthermore, the ratio of cadmium chloride, thiourea, and ethylenediamine is (2.5~3.5) g:(2.5~3.3) g:(80~100) mL, and the ratio of thioacetamide, sodium molybdate, and ethylenediaminetetraacetic acid is (70~90) mg:(15~25) mg:(80~100) mL. In step S1, the purpose of adding ethylenediamine is to induce the formation of rod-shaped structures. Simultaneously, the volume of ethylenediamine and ethylenediaminetetraacetic acid added in this invention directly affects the formation of highly dispersed, small-sized MoS2 on CdS nanorods. Due to the coexistence of the organic compounds ethylenediamine and ethylenediaminetetraacetic acid, an amorphous layer of organic matter mixed with MoS2 is formed on the surface of CdS nanorods after the hydrothermal reaction. The presence of organic matter not only ensures the high dispersion and ultra-small size of MoS2 on CdS nanorods but also provides space for subsequent MnO2 growth due to its occupancy effect.

[0019] Furthermore, in step S2, the hydrothermal reaction temperature is 150~210℃ and the time is 13~19 h. The temperature and time range of the hydrothermal reaction are to ensure the formation of MoS2 and the stable existence of organic site groups on the CdS surface.

[0020] Furthermore, in step S3, during the photodeposition reaction, the irradiation power of the xenon lamp is 200~250 W, the wavelength is 320~780 nm, and the irradiation time is 40~50 min. These conditions can effectively ensure the synthesis of MnO2. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The images shown are scanning electron microscope (SEM) images ((a), (b)) and transmission electron microscope (TEM) images ((c), (d)) of the CdS nanorods prepared in Comparative Example 1 of this invention at different magnifications. Figure 2 The CdS nanorods ((a1)~(a3)) prepared in Comparative Example 1, the CdS1 / Mo ((b1)~(b3)) prepared in Comparative Example 2, and the CdS1 / Mo / Mn prepared in Example 1 are examples of the present invention. 45 (c1)~(c3)) Transmission electron micrographs at different magnifications; Figure 3 The CdS1 / Mo(a) prepared in Comparative Example 2 and the CdS1 / Mo / Mn prepared in Example 1 of this invention. 45(b) EDS element distribution mapping diagram; Figure 4 The CdS nanorods prepared in Comparative Example 1, the CdS1 / Mo prepared in Comparative Example 2, and the CdS1 / Mo / Mn prepared in Example 1 are examples of the CdS nanorods prepared in Comparative Example 1 and Comparative Example 2, respectively. 45 The ultraviolet-visible absorption spectrum; Figure 5 The CdS nanorods prepared in Comparative Example 1, the CdS1 / Mo prepared in Comparative Example 2, and the CdS1 / Mo / Mn prepared in Example 1 are all from this invention. 45 XPS graph; Figure 6 The photocatalytic H2S degradation rate of the products obtained in Examples 1-3 and Comparative Examples 1-6 of this invention under 365 nm ultraviolet light irradiation; Figure 7 The CdS nanorods prepared in Comparative Example 1, the CdS1 / Mo prepared in Comparative Example 2, and the CdS1 / Mo / Mn prepared in Example 1 are examples of the CdS nanorods prepared in Comparative Example 1 and Comparative Example 2, respectively. 45 The relationship between illumination time and H2S concentration under 365 nm ultraviolet light irradiation; Figure 8 The CdSi / Mo / Mn prepared in Example 1 of this invention 45 Photocatalytic stability test results under 365 nm UV light irradiation; Figure 9 The CdS nanorods prepared in Comparative Example 1, the CdS1 / Mo prepared in Comparative Example 2, and the CdS1 / Mo / Mn prepared in Example 1 are examples of the CdS nanorods prepared in Comparative Example 1 and Comparative Example 2, respectively. 45 The relationship between illumination time and H2S concentration under 245 nm ultraviolet light illumination; Figure 10 The CdSi / Mo / Mn prepared in Example 1 of this invention 45 Photocatalytic stability test diagram under 245 nm ultraviolet light irradiation. Detailed Implementation

[0023] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0024] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0025] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0026] In this article, unless otherwise specified, the terms “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of”. For example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a”.

[0027] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0028] This invention provides a CdS / MoS2 / MnO2 photocatalyst comprising three components: CdS nanorods, a MoS2 modification layer, and MnO2 nanoparticles. The MoS2 modification layer coats the CdS nanorods to form CdS / MoS2, and the MnO2 nanoparticles are distributed in the areas of the CdS nanorods not covered by MoS2. A heterojunction is formed between the three components. In this heterojunction material, the mass ratio of CdS to MoS2 is 100:(0.05~0.15), and the mass ratio of CdS to MnO2 is 100:(2~4). Ratios that are too high or too low are detrimental to improving catalytic performance. The CdS nanorods have a length of 0.7~1.5 μm and a diameter of 40~70 nm; the MoS2, ethylenediamine, and ethylenediaminetetraacetic acid together form a coating layer with a thickness of 20~50 nm; the MnO2 is in nanoparticle form with a diameter of approximately 2~5 nm.

[0029] In addition, this invention also provides a method for preparing a CdS / MoS2 / MnO2 photocatalyst. CdS nanorods are prepared hydrothermally using cadmium chloride, thiourea, and ethylenediamine as raw materials. Based on this, MoS2-modified CdS nanorods are prepared hydrothermally using thioacetamide, sodium molybdate, and ethylenediaminetetraacetic acid as raw materials. MnO2 nanoparticles are grown on the MoS2-modified CdS nanorods using photodeposition with manganese acetate as raw material, resulting in a CdS / MoS2 / MnO2 ternary heterojunction photocatalyst with spatially separated dual active sites. Specifically, the method includes the following steps: here, ethylenediamine is both a solvent and a surfactant for the subsequent growth of MoS2. S1: Add 2.5~3.5 g of cadmium chloride (CdCl2•2.5 H2O) to 80~100 mL of ethylenediamine (EDA), sonicate for 8~12 min until completely dissolved, then add 2.5~3.3 g of thiourea (CH4N2S), stir at 400~600 r / min for 15~25 min until homogeneous, then place the mixture in a hydrothermal reaction at 160~200 ℃ for 30~42 h. After the product is allowed to stand overnight, remove the supernatant to obtain a CdS nanorod suspension with a concentration of 25~35 mg / mL. This CdS nanorod suspension was not washed.

[0030] S2: 70-90 mg of thioacetamide (TAA) and 15-25 mg of sodium molybdate (Na2MoO4·2H2O) were dispersed in 80-100 mL of ethylenediaminetetraacetic acid (EDTA). Then, 0.5-3.5 mL of the CdS nanorod suspension prepared in step S1 was added. The mixture was stirred at 400-600 r / min for 55-65 min until fully mixed. The mixture was then subjected to a hydrothermal reaction at 150-210 °C for 13-19 h. After the reaction was completed, the mixture was centrifuged at 6500-7500 r / min for 9-11 min to separate the solid and liquid components. The solid was washed three times with deionized water and ethanol. Finally, the solid was dried at 55-65 °C for 11-13 h to obtain MoS2-modified CdS nanorods (CdS / MoS2). The volume of added ethylenediamine and ethylenediaminetetraacetic acid (EDTA) directly affects the formation of highly dispersed, small-sized MoS2 on CdS nanorods. Due to the coexistence of the organic compounds ethylenediamine and EDTA, an amorphous layer of organic matter mixed with MoS2 is formed on the surface of the CdS nanorods after the hydrothermal reaction. The presence of the organic matter not only ensures the high dispersion and ultra-small size of MoS2 on the CdS nanorods but also provides space for subsequent MnO2 growth due to its occupancy effect.

[0031] S3: Add 25-35 mg of CdS / MoS2 obtained in step S2 to 10-15 mL of water and sonicate for 6-10 min. Then, add 5-15 mg of manganese acetate ((C2H3O2)2Mn·4H2O) under light-protected conditions and stir at 400-600 r / min for 20-40 min under light-protected conditions. After stirring evenly, place the mixture under a xenon lamp for photodeposition reaction. The xenon lamp irradiation power is 200-250 W, the wavelength is 320-780 nm, and the irradiation time is 40-50 min. After the reaction is completed, centrifuge at 6500-7500 r / min for 9-11 min to separate the solid and liquid. Wash the obtained solid three times with deionized water and ethanol, and dry at 55-65℃ for 11-13 h to obtain CdS nanorods co-modified with MoS2 and MnO2.

[0032] The xenon lamp irradiation power here is 200~250 W, and the irradiation time is 40~50 min. The irradiation power and time of the xenon lamp have a direct impact on the formation of MnO2 nanoparticles. During the irradiation process, under the dual action of high-energy ultraviolet light and CdS photocatalysis, the organic molecular chains are broken, and a large number of areas not covered by MoS2 appear on the CdS surface. As the irradiation time increases, the organic matter is consumed, the photogenerated electrons on CdS are rapidly captured by MoS2, while the holes are retained on the CdS surface, reacting rapidly with the Mn precursor to form MnO2 nanoparticles on the CdS surface.

[0033] This invention is to grow a CdS / MoS2 / MnO2 heterojunction photocatalyst on CdS nanorods by hydrothermal reaction and photodeposition, which has both MoS2 coating and MnO2 nanoparticles. The catalyst obtained by this technology has many significant advantages: (1) In this invention, the loading of electron trapping agent MoS2 and hole trapping agent MnO2 effectively improves the photocatalytic ability of CdS / MoS2 / Mn2 heterojunction. On the one hand, the strong electron trapping ability of MoS2 can effectively suppress charge recombination; on the other hand, the strong interaction between CdS and MnO2 changes the coordination environment of electrons on the CdS surface, resulting in charge transfer imbalance, which helps to improve charge transfer and suppress electron-hole recombination. (2) When the CdS / MoS2 / MnO2 heterojunction photocatalyst is placed in an H2S atmosphere, the holes accumulated on MnO2 will rapidly convert OH⁻ ions into hydroxyl radicals. At the same time, the remaining electrons accumulated on MoS2 will convert oxygen into superoxide radicals. The generation of these two reactive oxygen species can not only rapidly consume electrons and holes to improve the utilization rate of photogenerated carriers, but also significantly enhance the degradation effect of H2S through synergistic effect, thereby achieving a highly efficient pollutant degradation process. Therefore, the CdS / MoS2 / MnO2 catalyst of this invention is a heterojunction system with dual active sites, possessing both MoS2 reduction sites and MnO2 oxidation sites. Based on the construction of the heterojunction system, the spatial separation and uniform distribution of the dual active sites are achieved. Photogenerated electrons and holes are effectively separated by MoS2 and MnO2, respectively, leveraging the synergistic effect of MoS2 and MnO2. The introduction of the co-catalysts, namely MoS2 and MnO2, not only significantly broadens the light absorption range of CdS but also effectively suppresses the recombination of electrons and holes during the reaction, significantly improving the efficiency of the photocatalytic reaction. When the catalyst is placed in an H2S atmosphere, the catalyst with a rough surface can rapidly adsorb H2S and degrade it under light irradiation. Without adding any precious metal co-catalysts, the obtained CdS / MoS2 / MnO2 achieves a H2S degradation efficiency of up to 94.7% after irradiation with ultraviolet light (365 nm) for 2 h, indicating its excellent photocatalytic degradation ability of gaseous pollutants.

[0034] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0035] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0036] Example 1 A method for preparing a CdS / MoS2 / MnO2 photocatalyst includes the following steps: S1: 2.85 g of cadmium chloride was added to 60 mL of ethylenediamine and ultrasonically dispersed for 10 min to obtain a mixed solution. 2.85 g of thiourea was added to the mixed solution and stirred continuously at 500 r / min for 20 min. The mixture was then transferred to a Teflon-lined stainless steel autoclave and heated in a forced-air drying oven at 180 °C for 36 h. After allowing the product to stand overnight, the supernatant was removed with a pipette, yielding approximately 10 mL of unwashed CdS.

[0037] S2: 80 mg of thioacetamide and 20 mg of sodium molybdate were dispersed in 90 mL of ethylenediaminetetraacetic acid to obtain a homogeneous solution. 1.0 mL of unwashed CdS was added to the solution, and the mixture was stirred continuously at 500 r / min for 60 min to obtain a homogeneous mixture. This mixture was then transferred to a Teflon-lined stainless steel autoclave and heated in a forced-air drying oven at 180 °C for 16 h. The resulting product was centrifuged at 7000 r / min for 10 min, the supernatant was discarded, and the product was washed three times with deionized water and ethanol, and then dried at 60 °C for 12 h to obtain the product CdS / MoS2.

[0038] S3: 30 mg of CdS / MoS2 was dispersed in 12 mL of deionized water and sonicated for 10 min to obtain a homogeneous mixture. 10 mg of manganese acetate was added to the mixture, and the mixture was magnetically stirred at 500 r / min for 30 min in the dark to obtain a homogeneous mixture. The mixture was then irradiated under a 220 W xenon lamp for 45 min to perform a photodeposition reaction. The wavelength of the irradiation light was 320–780 nm. The obtained product was centrifuged at 7000 r / min for 10 min, the supernatant was discarded, and the product was washed three times with deionized water and ethanol. It was then dried at 60 °C for 12 h to obtain the CdS / MoS2 / MnO2 photocatalyst. In this example, the volume of unwashed CdS added was 1.0 mL, and the photodeposition time was 45 min; therefore, the product was labeled as CdS1 / Mo / MnO2.45 Photocatalyst.

[0039] The morphology of the catalyst prepared in this embodiment is as follows: Figure 2 As shown in (c1~c3), the amorphous MoS2 layer covering the surface of the CdS nanorods disappears, revealing a fluffy structure composed of tiny MnO2 nanoparticles with a diameter of approximately 3 nm. This confirms that MoS2 and MnO2 have been successfully deposited on the surface of the CdS nanorods. ICP testing of the obtained catalyst shows that the mass ratio of CdS:MoS2:MnO2 is 100:0.1:3. Its elemental distribution and UV-Vis absorption spectra are shown below. Figure 3 and Figure 4 As shown in the figure, the XPS graph is as follows Figure 5 As shown, the changes in light absorption behavior, along with the generation and shift of the XPS signal, jointly confirm the successful loading of MoS2 and MnO2 on the CdS sample surface. Figure 6 As shown, the catalyst achieved an H2S degradation efficiency of 94.7% after 2 h of irradiation with ultraviolet light (365 nm).

[0040] Example 2 The difference between this embodiment and Embodiment 1 is as follows: The photodeposition time was 30 min, and the resulting product was labeled CdS1 / Mo / Mn. 30 .

[0041] The catalyst showed an H2S degradation efficiency of 73.2% after 2 hours of UV irradiation.

[0042] Example 3 The difference between this embodiment and Embodiment 1 is as follows: The photodeposition time was 60 min, and the resulting product was labeled CdS1 / Mo / Mn. 60 .

[0043] The catalyst showed an H2S degradation efficiency of 80.1% after 2 hours of UV irradiation.

[0044] Comparative Example 1 The difference between this comparative example and Example 1 is as follows: To prepare CdS, only step S1 was performed. The product obtained in step S1 was centrifuged at 7000 r / min for 10 min, the supernatant was discarded, and the product was washed three times with deionized water and ethanol. The product was then dried at 60 °C for 12 h to obtain CdS nanorods.

[0045] from Figure 6 It can be seen that the catalyst has an H2S degradation efficiency of 37.3% after 2 h of ultraviolet light irradiation.

[0046] Comparative Example 2 The difference between this comparative example and Example 1 is as follows: Only CdS1 / Mo heterojunction catalysts were prepared, i.e., only steps S1 to S2 were performed. Specifically, CdS was directly mixed with the MoS2 precursor and subjected to a hydrothermal reaction.

[0047] from Figure 6 It can be seen that the catalyst has an H2S degradation efficiency of 60.2% after 2 h of ultraviolet light irradiation.

[0048] Comparative Example 3 The difference between this comparative example and Example 1 is as follows: Only CdS2 / Mo heterojunction catalysts were prepared, i.e. only steps S1~S2 were performed, and the volume of unwashed CdS added was 2 mL.

[0049] from Figure 6 It can be seen that the catalyst has an H2S degradation efficiency of 45.6% after 2 h of ultraviolet light irradiation.

[0050] Comparative Example 4 The difference between this comparative example and Example 1 is as follows: Only CdS3 / Mo heterojunction catalysts were prepared, i.e., only steps S1 to S2 were performed, and the volume of unwashed CdS added was 3 mL.

[0051] from Figure 6 It can be seen that the H2S degradation efficiency of this catalyst is 38.8% after 2 hours of light irradiation.

[0052] Comparative Example 5 The difference between this comparative example and Example 1 is as follows: In step S1, no organic site-occupying group ethylenediamine was added, and in step S2, no organic site-occupying group ethylenediaminetetraacetic acid was added. The rest was the same as in Example 1. The obtained product was labeled as CdS1-Mo / Mn. 45 .

[0053] The catalyst showed an H2S degradation efficiency of 52.5% after 2 hours of UV irradiation.

[0054] Comparative Example 6 The difference between this comparative example and Example 1 is as follows: The CdS obtained in step S1 was washed, and then steps S2 and S3 were performed, i.e., using the cleaned CdS nanorods as a substrate, the rest was the same as in Example 1, and the resulting product was labeled as CdS1-Mo-Mn. 45 .

[0055] The catalyst showed an H2S degradation efficiency of 63.3% after 2 hours of UV irradiation.

[0056] Example 3 A method for preparing a CdS / MoS2 / MnO2 photocatalyst includes the following steps: S1: 2.5 g of cadmium chloride was added to 80 mL of ethylenediamine and sonicated for 8 min until completely dissolved. Then, 2.5 g of thiourea was added and stirred at 400 r / min for 25 min until homogeneous. The mixture was then placed in a hydrothermal reaction at 160 ℃ for 42 h. After the product was allowed to stand overnight and the supernatant was removed, a CdS nanorod suspension with a concentration of 25 mg / mL was obtained. This CdS nanorod suspension was not washed.

[0057] S2: 70 mg of thioacetamide and 15 mg of sodium molybdate were dispersed in 80 mL of ethylenediaminetetraacetic acid, and then 0.5 mL of the CdS nanorod suspension prepared in step S1 was added. The mixture was stirred at 400 r / min for 65 min and thoroughly mixed. The mixture was then subjected to a hydrothermal reaction at 150 ℃ for 19 h. After the reaction was completed, the mixture was centrifuged at 6500 r / min for 11 min to separate the solid and liquid components. The solid was washed three times with deionized water and ethanol. Finally, the solid was dried at 55 ℃ for 13 h to obtain MoS2-modified CdS nanorods (CdS / MoS2).

[0058] S3: Add 25 mg of CdS / MoS2 obtained in step S2 to 10 mL of water and sonicate for 6 min. Then, add 5 mg of manganese acetate under light-protected conditions and stir at 400 r / min for 40 min under light-protected conditions. After stirring evenly, place the mixture under a xenon lamp for photodeposition reaction. The xenon lamp has an irradiation power of 220 W, a wavelength of 320~780 nm, and an irradiation time of 50 min. After the reaction is completed, centrifuge at 6500 r / min for 11 min to separate the solid and liquid. Wash the obtained solid three times with deionized water and ethanol and dry it at 55℃ for 13 h to obtain CdS nanorods co-modified with MoS2 and MnO2.

[0059] Example 4 A method for preparing a CdS / MoS2 / MnO2 photocatalyst includes the following steps: S1: Add 3.5 g of cadmium chloride to 100 mL of ethylenediamine and sonicate for 12 min until completely dissolved. Then add 3.3 g of thiourea and stir at 600 r / min for 25 min until homogeneous. Then place the mixture in a hydrothermal reaction at 200 ℃ for 30 h. After the product is left to stand overnight, remove the supernatant to obtain a CdS nanorod suspension with a concentration of 35 mg / mL. This CdS nanorod suspension was not washed.

[0060] S2: 90 mg of thioacetamide and 25 mg of sodium molybdate were dispersed in 100 mL of ethylenediaminetetraacetic acid, and then 3.5 mL of the CdS nanorod suspension prepared in step S1 was added. The mixture was stirred at 600 r / min for 55 min and thoroughly mixed. The mixture was then subjected to a hydrothermal reaction at 210 ℃ for 13 h. After the reaction was completed, the mixture was centrifuged at 7500 r / min for 9 min to separate the solid and liquid components. The solid was washed three times with deionized water and ethanol. Finally, it was dried at 65 ℃ for 11 h to obtain MoS2-modified CdS nanorods (CdS / MoS2).

[0061] S3: Add 35 mg of CdS / MoS2 obtained in step S2 to 15 mL of water, sonicate for 10 min, then add 15 mg of manganese acetate under light-protected conditions, stir at 600 r / min for 20 min under light-protected conditions, and after stirring evenly, place the mixture under a xenon lamp for photodeposition reaction. The xenon lamp has an irradiation power of 220 W, a wavelength of 320~780 nm, and an irradiation time of 50 min. After the reaction is completed, centrifuge at 7500 r / min for 9 min to separate the solid and liquid. Wash the obtained solid three times with deionized water and ethanol, and dry at 65℃ for 11 h to obtain CdS nanorods co-modified with MoS2 and MnO2.

[0062] Example 5 A method for preparing a CdS / MoS2 / MnO2 photocatalyst includes the following steps: S1: Add 3.0 g of cadmium chloride to 90 mL of ethylenediamine and sonicate for 10 min until completely dissolved. Then add 3.0 g of thiourea (CH4N2S) and stir at 500 r / min for 20 min until homogeneous. Then place the mixture in a hydrothermal reaction at 180 ℃ for 35 h. After the product is left to stand overnight, remove the supernatant to obtain a CdS nanorod suspension with a concentration of 30 mg / mL. This CdS nanorod suspension was not washed.

[0063] S2: 80 mg of thioacetamide and 20 mg of sodium molybdate were dispersed in 90 mL of ethylenediaminetetraacetic acid, and then 2 mL of the CdS nanorod suspension prepared in step S1 was added. The mixture was stirred at 500 r / min for 60 min and thoroughly mixed. The mixture was then subjected to a hydrothermal reaction at 200 ℃ for 16 h. After the reaction was completed, the mixture was centrifuged at 7000 r / min for 10 min to separate the solid and liquid. The solid was washed three times with deionized water and ethanol. Finally, the solid was dried at 60 ℃ for 12 h to obtain MoS2-modified CdS nanorods (CdS / MoS2).

[0064] S3: Add 30 mg of CdS / MoS2 obtained in step S2 to 12 mL of water and sonicate for 8 min. Then, add 10 mg of manganese acetate under light-protected conditions and stir at 500 r / min for 30 min under light-protected conditions. After stirring evenly, place the mixture under a xenon lamp for photodeposition reaction. The xenon lamp has an irradiation power of 220 W, a wavelength of 320~780 nm, and an irradiation time of 45 min. After the reaction is completed, centrifuge at 7000 r / min for 10 min to separate the solid and liquid. Wash the obtained solid three times with deionized water and ethanol and dry it at 60℃ for 12 h to obtain CdS nanorods co-modified with MoS2 and MnO2.

[0065] Table 1 shows the relative content ratios of the products obtained in Examples 1-3 and Comparative Examples 2-4 of this invention, as determined by ICP-MS and estimated. As shown in Table 1, in Examples 1-3, the relative mass of MoS2 was approximately 0.11% of the mass of CdS. With the light irradiation time increasing by 60 minutes from 30 and 45 degrees Celsius, the relative mass of MnO2 increased from 2.25% and 3.16% to 3.82%, demonstrating that MnO2 gradually grew on the catalyst surface through photodeposition. However, overall, the contents of both MoS2 and MnO2 were much lower than those of CdS. The low concentrations of MoS2 and MnO2 acted as electron and hole trapping centers on the CdS surface, respectively, playing a co-catalyst role in accelerating the catalytic reaction.

[0066] Table 1

[0067] Figure 1 The images show the scanning ((a), (b)) and transmission electron microscopy ((c), (d)) images of the CdS nanorods prepared in Comparative Example 1 of this invention at different magnifications. As can be seen from the images, the CdS nanorods have a diameter of about 50-70 nanometers and a length of 2-3 micrometers. The nanorods are uniform in size, have a smooth and flat surface, and are not adhered to each other.

[0068] Figure 2 The CdS nanorods ((a1)~(a3)) prepared in Comparative Example 1, the CdS1 / Mo ((b1)~(b3)) prepared in Comparative Example 2, and the CdS1 / Mo / Mn prepared in Example 1 are examples of the present invention. 45 Transmission electron microscopy (TEM) images (c1)~(c3) at different magnifications. As shown in the figures, after introducing MoS2, an approximately 30 nm thick amorphous layer can be clearly observed on the surface of the CdS nanorods. After MnO2 modification (CdS1 / Mo / Mn...),... 45 The amorphous layer covering the surface of the CdS nanorods disappears, replaced by a fluffy structure composed of MnO2 nanoparticles with a diameter of about 3 nm.

[0069] Figure 3 The CdS1 / Mo(a) prepared in Comparative Example 2 and the CdS1 / Mo / Mn prepared in Example 1 of this invention. 45 (b) shows the EDS elemental distribution mapping. The figure indicates that a small amount of Mo was detected in CdS1 / Mo, suggesting a low MoS2 loading. For CdS1 / Mo / Mn... 45 MnO2 was deposited more abundantly on CdS nanorods than MoS2. Mn and O elements exhibited similar cluster aggregation in the same regions of the CdS nanorods, which is attributed to the formation of MnO2 nanoparticles. Furthermore, the addition of ethylenediamine and ethylenediaminetetraacetic acid effectively inhibited MoS2 aggregation. Based on SEM and TEM results, it can be seen that MoS2 and MnO2 were successfully deposited on the surface of the CdS nanorods.

[0070] Figure 4 The CdS nanorods prepared in Comparative Example 1, the CdS1 / Mo prepared in Comparative Example 2, and the CdS1 / Mo / Mn prepared in Example 1 are examples of the CdS nanorods prepared in Comparative Example 1 and Comparative Example 2, respectively. 45 The UV-Vis absorption spectra of CdS show that the introduction of MoS2 and MnO2 significantly improved the light absorption performance of CdS. Simultaneously, the changes in the sample's light absorption behavior also indirectly confirm the successful loading of MoS2 and MnO2 onto the CdS surface.

[0071] Figure 5 The CdS nanorods prepared in Comparative Example 1, the CdS1 / Mo prepared in Comparative Example 2, and the CdS1 / Mo / Mn prepared in Example 1 are all from this invention. 45 From the XPS graph, it can be seen that CdS1 / Mo / Mn 45 Signal peaks for Cd, Mo, S, Mn, and O can be clearly observed. By analyzing their valence states and chemical environment, it can be found that MoS2 and MnO2 were successfully introduced into the sample. Furthermore, the introduced MoS2 and MnO2 interact strongly with the CdS substrate and cause changes in the electronic environment around CdS.

[0072] This invention uses a photocatalytic system (Zhongjiao Jinyuan) to test the photocatalytic removal capacity of the sample for H2S. The photodegradation experiments were conducted under ultraviolet light irradiation at 365 nm and 254 nm, respectively. 20 mg of the synthesized sample was ultrasonically dispersed in 5 mL of ethanol. The dispersion was drop-coated onto the bottom of an inverted circular beaker with a radius of 3 cm and thoroughly dried to obtain a reaction system with catalyst powder evenly distributed. O2 (20% vol), N2 (80% vol), and H2S were introduced into the reaction system via a humidifier using a mass flow meter. The gas was continuously introduced for 30 min to ensure a humidity of 60% to simulate an indoor environment, with an H2S concentration of 30 ppm. During the photocatalytic process, a bandpass filter with a wavelength of 365 nm ± 10 nm was added to a xenon lamp light source (320~780 nm) to provide ultraviolet light for irradiation of the sample. The distance between the light source and the catalyst was 15 cm, and the irradiation power reaching the catalyst surface was 0.9 mW / cm². 2 The system temperature was maintained at 25 °C using circulating cooling water, and a gas circulation pump was used to ensure uniform gas diffusion within the reaction system. The residual H2S after photocatalysis was monitored in real-time using online chromatography, with sampling points spaced 20 min apart, and the cumulative illumination time for each sample in a single cycle was 120 min. Similarly, in the same apparatus, a 254 nm UV lamp was used for photodegradation experiments, with the distance between the light source and the catalyst being 10 cm, and the irradiance reaching the catalyst surface being 0.3 mW / cm². 2 The remaining reaction and test conditions were consistent with those at a wavelength of 365 nm, and the cumulative illumination time for each sample in a single cycle was 180 min.

[0073] Figure 6 The photocatalytic H2S degradation rate of the products obtained in Examples 1-3 and Comparative Examples 1-6 of this invention under 365 nm ultraviolet light irradiation; Figure 7 The CdS nanorods prepared in Comparative Example 1, the CdS1 / Mo prepared in Comparative Example 2, and the CdS1 / Mo / Mn prepared in Example 1 are examples of the CdS nanorods prepared in Comparative Example 1 and Comparative Example 2, respectively. 45 The relationship between illumination time and H2S concentration under 365 nm ultraviolet light illumination is shown in the figure. It can be seen that pure CdS has low photocatalytic activity, but its performance in photocatalytic H2S degradation is improved after combining with MoS2 to form a CdS / Mo heterojunction. This is because the formation of the heterojunction promotes the effective separation of photogenerated electrons. After introducing MnO2, the resulting CdS1 / Mo / Mn... 45 It exhibits further improved photocatalytic activity, due to MoS2 and MnO2 acting as electron and hole traps respectively, enabling rapid separation of photogenerated electrons and holes to achieve H2S degradation. Furthermore, when CdS1 / Mo / Mn... 45The degradation efficiency of H2S reached 94.7% after 2 hours of light irradiation, indicating its potential in the degradation of organic pollutants.

[0074] Figure 8 The CdSi / Mo / Mn prepared in Example 1 of this invention 45 The photocatalytic stability test results under 365 nm UV light irradiation show that CdS1 / Mo / Mn 45 It exhibited good stability in all 5 cycles of photodegradation testing.

[0075] Meanwhile, this invention investigated the degradation effect of different samples on H2S under 254 nm ultraviolet light irradiation. Figure 9 The CdS nanorods prepared in Comparative Example 1, the CdS1 / Mo prepared in Comparative Example 2, and the CdS1 / Mo / Mn prepared in Example 1 are examples of the CdS nanorods prepared in Comparative Example 1 and Comparative Example 2, respectively. 45 The graph shows the relationship between irradiation time and H2S concentration under 245 nm UV light. As can be seen from the graph, the order of relative photodegradation activity among different samples is the same as that under 365 nm UV light irradiation, indicating that the catalyst in this invention has a wide wavelength applicability for photocatalytic degradation of H2S in the UV band. Without a catalyst, the degradation rate of H2S after the same irradiation time under 254 nm UV light is slightly higher than that under 365 nm UV light. This is because the high energy of the 254 nm UV light itself can break the HS bonds, causing partial degradation.

[0076] Figure 10 The CdSi / Mo / Mn prepared in Example 1 of this invention 45 The photocatalytic stability test results under 245 nm UV light irradiation are shown in the figure. As can be seen from the figure, after 3 h of irradiation, the CdS1 / Mo / Mn prepared in Example 1... 45 The degradation rate of H2S reached 91.4%, and it remained stable in 5 cycles of testing.

[0077] This invention proposes a CdS / MoS2 / MnO2 photocatalyst with spatially separated dual active sites and its preparation method. In the catalyst, independent and uniformly distributed MoS2 reduction sites and MnO2 oxidation sites are successfully constructed on the surface of CdS nanorods using a chemical occupancy strategy and photodeposition, resulting in a CdS / MoS2 / MnO2 photocatalyst with spatially separated dual active sites. The obtained photocatalyst not only achieves nanoscale spatial separation of electron and hole enrichment sites but also ensures the uniform distribution of the dual active sites on the CdS surface. This unique structural design effectively suppresses carrier recombination while ensuring rapid electron / hole migration, exhibiting excellent photocatalytic pollutant degradation performance in H2S atmospheres.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a CdS / MoS2 / MnO2 photocatalyst, characterized in that, Comprising the following steps: S1: adding cadmium chloride into ethylenediamine, ultrasonic to completely dissolve, then adding thiourea, stirring and mixing uniformly, then carrying out hydrothermal reaction on the mixture to prepare a CdS nanorod suspension; S2: dispersing thioacetamide and sodium molybdate in ethylenediaminetetraacetic acid, then adding the CdS nanorod suspension to carry out hydrothermal reaction to prepare a MoS2 modified CdS nanorod; S3: adding the MoS2 modified CdS nanorod into water, then adding manganese acetate under light shielding condition, stirring uniformly under light shielding, then placing the mixture under a xenon lamp to carry out photodeposition reaction, after the reaction is completed, the CdS / MoS2 / MnO2 photocatalyst is prepared.

2. The preparation method of the CdS / MoS2 / MnO2 photocatalyst according to claim 1, characterized in that, In step S1, the amount ratio of cadmium chloride, thiourea and ethylenediamine is (2.5-3.5) g:(2.5-3.3) g:(80-100) mL.

3. The preparation method of the CdS / MoS2 / MnO2 photocatalyst according to claim 1, characterized in that, In step S1, the temperature of the hydrothermal reaction is 160-200℃, and the time is 30-42 h.

4. The preparation method of the CdS / MoS2 / MnO2 photocatalyst according to claim 1, characterized in that, In step S2, the amount ratio of thioacetamide, sodium molybdate and the CdS nanorod suspension is (70-90) mg:(15-25) mg:(0.8-3.2) mL, and the concentration of the CdS nanorod suspension is 25-35 mg / mL.

5. The method for preparing a CdS / MoS2 / MnO2 photocatalyst according to claim 1, characterized in that, In step S2, the amount ratio of thioacetamide, sodium molybdate and ethylenediaminetetraacetic acid is (70-90) mg:(15-25) mg:(80-100) mL.

6. The preparation method of the CdS / MoS2 / MnO2 photocatalyst according to claim 1, characterized in that, In step S2, the temperature of the hydrothermal reaction is 150-210℃, and the time is 13-19 h.

7. The method for preparing a CdS / MoS2 / MnO2 photocatalyst according to claim 1, characterized in that, In step S3, the mass ratio of the MoS2 modified CdS nanorod and manganese acetate is (25-35):(5-15).

8. The preparation method of the CdS / MoS2 / MnO2 photocatalyst according to claim 1, characterized in that, In step S3, during the photodeposition reaction, the irradiation power of the xenon lamp is 200-250 W, the wavelength is 320-780 nm, and the irradiation time is 40-50 min.

9. A CdS / MoS2 / MnO2 photocatalyst, characterized in that, Prepared by the method in any one of claims 1-8.

10. Application of the CdS / MoS2 / MnO2 photocatalyst in claim 9 in photocatalytic H2S removal.

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