Design And Application Of MoS₂/TiO₂ Nanotube Arrays Composites

With the continuous development of economic globalization and industrialization,environmental pollution and energy crisis have gradually become an important problem restricting the development of human society.According to the data,in 2014,the total discharge of sewage in China was as high as 71.6 billion tons.The cost of equipment used to maintain wastewater treatment reached 66 billion,of which the entire textile printing and dyeing garment accounted for 22 billion,which seriously hindered the development of social economy.As the world's largest textile printing and dyeing industry,China produces nearly 700,000 tons of various dyes each year,some of which are mixed with the environment,which seriously threatens China's ecological environment.Therefore,in order to maintain the ecological balance and achieve a green economy,it is necessary to actively carry out water pollution prevention and control.In order to alleviate the above problems,researchers have developed a number of methods,in which photocatalytic degradation of pollutants technology has become an important development direction in the field of environmental protection.As an excellent photocatalytic semiconductor material,titanium dioxide nanotube arrays(titanium dioxide NT As)can provide more reactive sites and charge transfer channels because of their unique axial geometry.At the same time,they can greatly reduce the loss of electrons in the formation of heterojunction interactions.However,due to the band gap and chemical properties of titanium dioxide,it can only absorb ultraviolet light without visible light and has poor electrocatalytic activity for water decomposition.In order to solve this key scientific problem,MoS2,a typical two-dimensional narrow band gap semiconductor material,was used as a modified material to design the MoS2/TiO2 composite electrode.The light response range of the composite electrode and the active sites of the photocatalysis of the composite electrode were greatly improved,and the heterojunction between the two materials promoted electricity.These advantages make the MoS2/TiO2 nanotube arrays(MoS2/TiO2 NTAs)composite electrode have remarkable effects on photocatalytic degradation of pollutants,surface Raman enhancement and electrocatalytic decomposition of water.The main research work is as follows:(1)MoS2 quantum dots(QDs)/TiO2 nanotube array composites were prepared by one-step electrochemical exfoliation and electrophoretic deposition.The photoelectric properties of the composite electrodes,electrocatalytic decomposition of water and photocatalytic degradation of pollutants were investigated.The results show that the composite electrode with MoS2 QDs has better photocatalytic performance and photoelectric conversion efficiency than pristine TiO2 NTAs.(2)A ternary Pt/VG-MoS2/TiO2 NTAs heterojunction were fabricated by hydrothermal method and cyclic voltammetry.The results of EDS,XPS and SEM showed that sulfur-rich MoS2 nanosheet arrays can effectively rivet the Pt particles at the edge sites.At the same time,the results of Mott-Schottky junction test showed that the formation of p-type semiconductor MoS2 and n-type semiconductor TiO2 heterojunction greatly promotes the charge transfer and charge concentration.The results show that the SERS enhancement factor is 2.1 ×105,and the photocatalytic degradation efficiency under visible light irradiation is more prominent than that of other TiO2 NTAs-based materials.