Fabrication Ang Investigation On Photocatalytic Properties Of ZnO Nanorods

In this thesis,ZnO nanorods were prepared by hydrothermal method,and the process conditions for the growth of ZnO nanorods were optimized.Then Ag decorated ZnO nanorods and Ag₂O decorated ZnO nanorods were prepared by photodeposition and two-times hydrothermal method respectively.The effects of Ag and Ag₂O decorations on photocatalytic performance of ZnO nanorods were also investigated respectively.The results are obtained as below:1.Optimization of process conditions for the growth of ZnO nanorods:the hydrothermal method was used to prepare ZnO nanorods,and the effects of the concentrations of polyethyleneimine,zinc source,as well as the number of seed layer on the morphologies and optical properties of ZnO nanorods were investigated.The purpose of the optimization of processing conditions for ZnO nanorods growth was to prepare ZnO nanorods with small diameter,low density and well orientation.The diameter of ZnO nanorods decreased and then increased with the increasing of polyethylenimine concentration.When the polyethylenimine concentration was 0.012mol/L the diameter of the prepared ZnO nanorods was the smallest.Therefore,the polyethylenimine concentration for the preparation of ZnO nanorods was determined as 0.012 mol/L.The density and orientation of ZnO nanorods increased with the increase of zinc source concentration in the hydrothermal reaction solution,and the concentration of zinc source in the hydrothermal reaction was determined to be 0.03mol/L.The density of ZnO nanorods increased with the number of seed layers,the number of seed layer was determined to be 1 layer.2.Photocatalytic properties of Ag decorated ZnO nanorods:pure ZnO nanorods were firstly prepared by hydrothermal method,and then Ag decorated ZnO nanorods were prepared by photodeposition to investigate the effects of photodeposition time and AgNO₃ concentration on the photocatalytic performance of Ag decorated ZnO nanorods.The results showed that with the increase of photodeposition time,the photocatalytic performance of ZnO nanorods increased firstly and then decreased.The degeneration of photocatalytic performance at further long deposition time was caused by the agglomeration of excess Ag particles,which occupied the reaction sites of ZnO nanorods,and the utilization of light was thereby reduced.The photocatalytic properties of ZnO nanorods decreased with the increase of concentration of AgNO₃firstly and then dropped,and the best photocatalytic performance appeared in the sample prepared with the concentration of AgNO₃ of 0.003 mol/L,which suggested that the suitable amount of Ag modification could significantly improve the photocatalytic performance of ZnO,while the excessive Ag decoration could form recombination center of photo-generated electrons and holes and resulted in the decrease of photocatalytic properties of ZnO nanorods.3.Photocatalytic properties of Ag₂O decorated ZnO nanorods:the Ag₂O decorated ZnO nanorods were prepared via hydrothermal method,and its photocatalytic performance was investigated.The results showed that the photocatalytic performance of Ag₂O decorated ZnO nanorods was much improved compared with ZnO powder.