Study On Photocatalytic Performance Of MX₂?M=Mo;X=S? Transition Metal Chalcogenide

Molybdenum disulfide?MoS₂?has received great attention in the field of photocatalysis due to its unique layered crystal structure and physicochemical properties.The thicker block MoS₂ is an indirect band gap of 1.2 eV and the single layer or several layers of MoS₂ nanosheets?two-dimensional nanomaterials?is a direct band gap of 1.96 eV.Due to the quantum effect and the unique band structure of MoS₂ nanomaterials,it can fully absorb visible light.Nowadays,MoS₂nanomaterials have been widely used in many fields such as photocatalysis,solar cells,optoelectronic devices and FETs.In order to further improve the photocatalytic performance of MoS₂,researchers have modified MoS₂ by doping,modification and formation of composite materials,which has important practical significance for promoting the design and efficient utilization of new two-dimensional photocatalytic materials.This thesis mainly studies the photocatalytic performance of MoS₂.The main contents are as follows:1.The 1T@2H-MoS₂/Au nanosheet structure coated with Au nanoparticles?Au NPs?was prepared by simple hydrothermal method and chemical reduction method.XRD,EDS,TEM,XPS characterization analysis confirmed that the sample consisted of Au NPs,1T phase and 2H phase MoS₂.The photocatalytic degradation of methylene blue?MB?by 1T@2H-MoS₂/Au nanosheets achieved as high as 91.2%under the experimental conditions of 350W Xenon lamp illumination at room temperature.The introduction of Au NPs effectively improved the degradation efficiency of 1T@2H-MoS₂/Au nanosheets.The local surface plasmon resonance?LSPR?of Au NPs in composites under illumination will significantly enhance the visible light absorption of 1T@2H-MoS₂ nanosheets.The Au NPs introduced in the1T@2H-MoS₂ nanosheet structure,the thermal electrons generated by Au NPs under visible light irradiation promote the conversion of 2H phase to 1T phase in1T@2H-MoS₂,and the high 1T phase content effectively improves the visible light catalytic performance.The synergy between the high content of 1T phase and Au NPs in 1T@2H-MoS₂ accelerates the transfer of photogenerated electrons,thereby inhibiting the recombination of photogenerated electron-hole pairs and allowing more electrons to participate in the catalytic reaction.2.Au nanoparticles?NPs?and Ag nanoparticles?NPs?bimetallic supported1T@2H-MoS₂/Au/Ag nanosheets were prepared by deposition-precipitation and photodeposition methods.XRD,EDS,TEM and XPS characterization showed that the sample consisted of Au NPs,Ag NPs,1T phase and 2H phase MoS₂.At room temperature,1T@2H-MoS₂/Au/Ag nanosheets degraded antibiotics?tetracycline hydrochloride?under visible light irradiation,and the degradation efficiency reached79.8%.First,the double noble metal nanoparticles?Au NPs and Ag NPs?supported on the 1T@2H-MoS₂ nanosheet structure generate local surface plasmon resonance?LSPR?under visible light,thereby enhancing the visible light absorption of1T@2H-MoS₂ nanosheets.Secondly,the synergistic effect between the double noble-metals enables the efficient transfer of photogenerated electrons in the1T@2H-MoS₂/Au/Ag nanosheets.The bimetal supported on the 1T@2H-MoS₂nanosheets can promote the conversion of the 2H phase to the 1T phase,and the high1T phase content can effectively enhance the photogenerated electron transfer,thereby suppressing the photogenerated electron-hole pairs recombination.Finally,the photocatalytic performance of the 1T@2H-MoS₂ nanosheets were enhanced.