The Synthesis Of Metal-TiO₂ Complex Photoelectrode Based On Surface Plasmon And The Study On Their Photocatalytic Activity

Titanium dioxide（TiO₂） is one of the widely investigated materials for photocatalysis because of its unique physical and chemical properties. The major obstacles to their enhancement of photocatalytic effective lie in poor photo-generated charge separation and inefficient use of sunlight. To date, a variety of studies have been utilized to improve TiO₂ photoelectrochemical performance, such as doping with nonmetal elements（N, F, S, I, etc.）, coupling with other semiconductors, modification by metal nanoparticles and modification of morphologies. In summary, This thesis is divided into the following two aspects: 1 Preparation of metal-dielectric-metal nanostructure and study of their photocatalytic properties.Based on the standard sputtering and thermal annealing techniques, we prepared a stable plasmonic photocatalyst with a metal-dielectric-metal（MDM） structure consisting of metal nanoparticles, wide bandgap semiconductor film TiO₂ and metal film. We demonstrate that the MDM nanostructure can take advantage of strong light absorption in the whole visible light range（from 400 nm to 750nm） to harvest hot electrons arising from gap-plasmon decay and consequently increase the photocurrent generation.In particular, a 5-fold enhancement in the incident photon-to-current conversion efficiency and a 3-fold enhancement in hydrogen production as compared to a conventional plasmonic photocatalyst（such as metal nanoparticles loaded TiO₂ film） are observed for the proposed MDM architecture. 2 Preparation of the Au nanoparticles modified TiO₂ nanotubes and study of their photocalytic properties.Au nanoparticles-decorated TiO₂ nanotube arrays were prepared by a facile method, which is thermal annealing thin gold film deposited on anodic oxidized TiO₂ nanotube arrays. These electron microscope images present that Au nanoparticles were well dispersed within the wall and on the surface of the TiO₂ nanotubes. Meanwhile, the morphologies of Au nanoparticles can be controlled by changing the thickness of the deposited gold film. Associated with the excitation of LSPRs, the prepared Au nanoparticle-decorated TiO₂ nanotube arrays could work as visible light responsive photocatalysts to produce a greatly enhanced photocurrent density. By varying the initial gold film thickness, Au nanoparticle-decorated TiO₂ nanotube arrays could be optimized to obtain the highest photocurrent generation efficiency in the visible light region.