Controllable Synthesis And Photocatalytic Performance Of Copper Doped Titanium Dioxide Nanomaterials

Titanium dioxide（TiO₂）is one of the common metal oxide semiconductors with a large bandgap,which was widely used in different fields including photocatalysis and sensors due to its less toxicity,low cost,good physicochemical stability and strong capacity of light absorption.However,TiO₂has large bandgap（E_g=3.0-3.2 e V）and can only absorb the ultraviolet light（λ<387 nm）,leading to poor photocatalytic performance in the visible region.In order to extend the spectral response range of the TiO₂photocatalyst and improve photocatalytic efficiency,it is necessary and meaningful to modify the TiO₂.Among different approaches,the doping of transition metal ions into TiO₂is one of the effective methods.Among various transition metal ionsdoped TiO₂,copper-doped TiO₂nanocrystals have attracted much attention due to their low cost,high photocatalytic activity and high absorption ability in the visible light region.Therefore,in this thesis,hydrothermal and hot-injection methods were used to synthesize copper-doped TiO₂nanomaterials,and the effects of the doping amount and morphology as well as the crystal structure on the photocatalytic performance was studied.The research work is summarized as follows:（1）TiO₂nanowires were synthesized through a hydrothermal method by using titanium oxide（IV）powder as a titanium source.Then,different-shaped Cu-doped TiO₂nano-and micro-crystals were synthesized by using Cu Cl and Cu Cl₂as copper sources,respectively.The effects of Na OH concentration,hydrothermal time,the amount of precursors and calcination temperature on the growth of TiO₂nanowires were explored.According to the experimental results from transmission electron microscopy（TEM）,ultraviolet-visible diffuse reflectance（UV-Vis DRS）and Brunner-Emmet-Teller（BET）measurements,the doping amount of Cu ions played an important role in the tuning of the morphology of resultant products,and the shape varied from linear to tubular.At the same time,the bandgap decreased and the specific surface area increased.The X-ray photoelectron spectroscopy（XPS）results indicated that the valence state of copper element was+1 in the Cu-doped TiO₂nanostructures.Finally,it was found that the photocatalytic activity of the Cu-doped TiO₂nanostructures was better than other samples when the Na OH concentration was 10M and the Cu dopant concentration was5%.（2）TiO₂nanorods were synthesized through a hot-injection method by using titanium tetrachloride as the titanium source.Then,Cu-doped TiO₂nanorods were synthesized by using copper acetylacetonate and copper acetate as the Cu source,respectively.By adjusting the amount of Ti precursors,the effects of Ti precursors on the morphology and size of TiO₂nanorods were explored.X-ray diffractometer（XRD）and transmission electron microscopy（TEM）showed that TiO₂nanorods were brookite nanorods.The size was increased as the amount of precursors was increasing.The ultraviolet absorption spectroscopy was used to study the effects of Cu-doping on the absorption properties.Finally,the sample synthesized in the presence of 5%copper acetylacetonate exhibited better photocatalytic activity.