Preparation And Performance Study Of Single Crystal TiO₂(B) Nanorod-based Composite Visible Light Photocatalyst

With the increasing demand for economy and the development of industrial technology,the application of traditional energy sources such as coal and petroleum have been overspent resulting in severe environmental issues and energy crises.In order to solve this calamity,semiconductor photocatalysis technology was chosen to degrade organic pollutants and promote hydrogen production via the water splitting process.TiO₂?B?semiconductor is widely used because of its non-toxic and low cost,but the separation efficiency of photogenerated e^--h⁺pairs in TiO₂?B?is still unsatisfactory,and its intrinsically large band gap restricts its catalytic activity in the visible light region.This paper combined the TiO₂?B?with other semiconductor by forming a heterojunction structure to promotes the separation of photo-generated charge.Simultaneously,the absorption capacity of the visible light is improved by introducing the Ti³⁺into the composite system through the surface engineering.The degradation effects of composite photocatalysts on several common pollutants under visible light and their ability to produce hydrogen were emphatically analyzed,and the photocatalytic mechanisms of as-prepared composites visible-light materials have also been discussed.The main contents of this thesis are as follows:?1?TiO₂?B?nanorods were synthesized by a hydrothermal method,and then strontium hydroxide was used as strontium source in a second hydrothermal reaction.Then SrTiO_3-x/TiO_2-x?B?composite visible-light pholocatalyst was synthesized by in-situ reduction method.The degradation efficiency of phenol is 95%and the reduction efficiency of Cr?VI?94%under visible light.Simultaneously,the hydrogen production efficiency under simulated sunlight irradiation is 160.2?mol·h^-1·g^-1.According to the characterization and performance test of synthetic materials,the mechanism of catalytic action was put forward.Two semiconductors contact closely by a hydrothermal reaction to form a heterojunction,which provides a bridge for charge transfer thus it speeds up the transmission of photo-generated charges.Secondly,the introduction of Ti³⁺broadens the range of photocatalytic response.?2?Ag-TiO_2-x?B?/g-C₃N₄ composite visible-light photocatalysts were fabricated by hydrothermal-calcination,photo-deposition procedure,and followed by in-situ solid-state chemical reduction procedure.The photocatalytic degradation efficiency of phenol and ammonia nitrogen under visible light were 98%and 93%,respectively.The catalytic reduction efficiency of Cr?VI?can reach 95%,and a hydrogen production efficiency of 410?mol·h^-1·g^-1 was obtained under simulated sunlight irradiation.On the basis of a series of characterization and performance tests,the corresponding catalytic mechanism was also be proposed.Firstly,the heterojunction structure was formed by calcination between nanorods and nanosheets.Secondly,the introduction of Ti³⁺into the TiO₂?B?is beneficial to shorten its band gap width,this keeps the preservation of photocatalysis in the light beyond the ultraviolet region.The synergistic effect of heterojunction structure and Ti³⁺improves the photocatalytic activity under visible light.In addition,the SPR effect of Ag nanoparticles further promotes electron transfer...