Preparation Of Composite Catalyst Composed Of MoS₂ And Pelagic Clay And Its Photocatalytic And Catalytic Hydrogenation Performance

With the rapid development of society,environmental problems faced by human beings are becoming more and more severe.The negative effects brought by traditional treatment methods make it a research focus to find efficient and environmental-friendly solutions.Therefore,more and more photocatalysts and chemical catalysts have received tremendous attention,and have been widely applied in the field of environmental protection.Molybdenum disulfide（MoS₂）is one of them.Due to its semiconductor properties and two-dimensional layered structure,MoS₂ has been gradually applied in the field of photocatalysis in recent years.Moreover,molybdenum disulfide also has chemical catalytic performance,and has been widely used in the field of hydrodesulfurization of petroleum-related industries.However,the catalytic performance of bulk molybdenum disulfide is not very good.Therefore,how to improve the catalytic performance of molybdenum disulfide as an environmental catalyst has become a research hotspot.The composite of MoS₂ with some materials can reduce the aggregation of MoS₂nanosheets,expose more active sites,or reduce the number of stacked layers of MoS₂nanosheets,and thus improve their light utilization efficiency to achieve the purpose of improving catalytic performance of MoS₂.Considering the high structural activity,strong adsorption,and good hydrophilicity of pelagic clay,this paper prepared the composite catalysts by combining MoS₂ with pelagic clay.The photocatalytic performance and catalytic hydrogenation performance of the composite catalysts were studied and the corresponding mechanism explanations were given.Firstly,the composite catalyst composed of 2H MoS₂ and pelagic clay（2H-MoS₂/PC）was prepared by one-step hydrothermal method,and its performance in photocatalytic degradation of antibiotics and photocatalytic disinfection was studied.In photocatalytic degradation experiments,the degradation rate of 2H-MoS₂/PC to tetracycline hydrochloride under visible light was 76.82%,which was much higher than that of bulk molybdenum disulfide（30.28%）.In photocatalytic disinfection experiments,2H-MoS₂/PC showed a disinfection rate of 99.95%to E.coli.8739 within18 h under visible light,which was higher than that of bulk 2H MoS₂（61.87%）under the same conditions.The results show that the higher photocatalytic performance of2H-MoS₂/PC is mainly attributed to the following three points:（1）Pelagic clay crystallized in the process of hydrothermal reaction,and formed illite/montmorillonite（I/M）mineral.The increased number of hydroxyl groups in I/M mineral decreases the recombination rate of photogenerated carriers through electrostatic interaction.（2）2H-MoS₂/PC shows a special symbiotic structure between I/M mineral and MoS₂.The symbiotic structure effectively inhibits the growth of MoS₂ nanosheets,resulting in a smaller lateral size,which is conducive to the diffusion of photogenerated electron-hole pairs to the edge of materials.（3）The excellent hydrophilicity of pelagic clay also significantly improved the hydrophilicity of MoS₂,which is conducive to its application in aqueous systems.Secondly,1T-MoS₂/PC composite catalyst composed of 1T MoS₂ and pelagic clay was prepared by one-step hydrothermal method,and its catalytic hydrogenation performance was studied via the catalytic reduction of 4-nitrophenol（4-NP）to 4-aminophenol（4-AP）with sodium borohydride.The catalytic hydrogenation performance test results showed that the catalytic hydrogenation performance of 1T MoS₂（88.50%）is better than that of bulk 2H MoS₂（82.42%）.The catalytic hydrogenation performance of 1T and 2H MoS₂ was improved after combined with pelagic clay.The catalytic hydrogenation performance of 1T-MoS₂/PC was 96.87%,while that of 2H-MoS₂/PC was 94.67%under the same conditions.The catalytic hydrogenation performance of 1T MoS₂ or 1T-MoS₂/PC is better than that of bulk 2H MoS₂ and 2H-MoS₂/PC.Moreover,some factors affecting the catalytic hydrogenation performance of 1T-MoS₂/PC were also explored,and the optimal conditions were optimized.The results showed that the higher catalytic hydrogenation performance of1T-MoS₂/PC is mainly attributed to the following three points:（1）the existence of pelagic clay significantly reduces the aggregation of MoS₂ nanosheets,so more active sites of MoS₂ nanosheets are exposed.（2）The hydrophilicity of pelagic clay is also beneficial for the application of MoS₂ in aqueous systems.