| In recent years,with the rapid development of social industries,severe environmental pollution and energy shortages have attracted global attention and attention.For example,environmental pollution caused by the discharge of industrial dye wastewater has caused people to pay attention to this issue.In order to solve the energy and environmental crisis,photoelectrochemical semiconductor materials are widely studied because they can convert solar energy into electrical or chemical energy.These energy conversions use only solar energy and almost no pollutants,so this is a green and continuous route.Professor Fujishima discovered in 1972 that TiO2 can obtain hydrogen and oxygen by photocatalytic decomposition of water,which has caused widespread concern in the environmental field,and semiconductor photocatalytic technology has developed rapidly.Semiconductor photocatalytic technology can not only make full use of abundant solar energy,but also meet the requirements of cheap and efficient hydrogen production and sewage purification,and has become one of the most promising environmental protection technologies.Among many photocatalyst materials,titanium dioxide(TiO2)has become a promising photocatalyst because of its excellent activity,low price,stability and non-toxicity.However,the band gap of TiO2 is wide,and the absorbed light band is in the ultraviolet band.However,this part of light accounts for only 5%of visible light and its solar utilization efficiency is low.In order to improve the photocatalytic activity of TiO2,we have synthesized different TiO2 exposed crystal planes and constructed heterojunctions with metal sulfide semiconductors to enhance the photocatalytic performance.The photocatalytic activity of TiO2 is affected by the crystal plane.The common anatase TiO2(101)plane is a low-energy plane.Therefore,by controlling the synthesis conditions,we study the anatase TiO2 and metal sulfide with different exposed crystal planes.The materials are compounded,and different crystal planes such as(101)plane,(001)plane,and curved surface are used to construct the heterojunction composite materia,which improves the photocatalytic performance.In addition,the photo-catalytic effect of two kinds of metal sulfides on the construction of heterojunctions was further studied,and the role of metal sulfides in the construction of heterostructures was discussed.The research content of this article is mainly divided into the following four parts:(1)Preparation of TiO2(TO,P25,ATO)with different crystal surfaces,and composite with Sb8O11Cl2to build a heterojunction,and the related photocatalytic activity was studied.The results show that this TiO2/Sb8O11Cl2 heterostructure is sensitive to the crystal plane.When Sb8O11Cl2 is compounded on the exposed(001)TiO2 nanosheets,the separation efficiency of photogenerated carriers is improved,and the relevant photocatalytic activity is the strongest.(2)The TiO2 nanosheets exposed on the(001)plane were composited with Bi2S3 to build a heterojunction.Compared with the original TiO2 and Bi2S,the Bi2S3/TiO2 photocatalyst shows a significant enhancement in photoelectrolysis H2.Experimental results confirm that the(001)plane exposed TiO2 nanosheets are very suitable for compounding with Bi2S3 rods to improve photoelectrochemical performance.(3)Anatase-type TiO2 nanodrum with exposed curved surface is compounded with two-dimensional MoS2 to form a heterojunction.The curved TiO2/MoS2 photocatalyst has 80%higher photocatalytic activity than the original curved TiO2 nanodrum.In contrast,a P25/MoS2 heterojunction was prepared,and the obtained sample with the highest photocatalytic activity showed only a 12%enhancement in effect over P25.The experimental results confirm that the curved surface of TiO2 is more suitable for composite MoS2 to improve the photocatalytic performance.(4)Nano-MnS is compounded with ultra-thin two-dimensional MoS2 nano-layers to build heterojunctions.Compared with the original MnS,this MnS/MoS2 heterojunction shows great improvement in photocatalytic and photoelectrochemical performance.The most active heterojunction composite has a 161%increase in photocatalytic activity and 11.5 times increase in photocurrent density. |
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