Abstract
The study of photocatalytic performance in this dissertation can be divided into two parts according the different material system. The first part is the fabrication of CNT/TiO2 core-shell structure by atomic layer deposition (ALD). A uniform TiO2 thin film with amorphous structure was directly deposited on CNT at 100 oC. CNT/TiO2 composite was then annealed under N2 atmosphere to form anatase phase of TiO2. The heterojunction of CNT/TiO2 core-shell structure lowers the electron and hole recombination rate, which results in high photocatalytic activity. In the meanwhile, the high specific surface area provided by CNT also enhances the efficiency of photodegradation. Besides, the TiO2 nanoparticles were formed on CNT rather than film when the growth temperature was increased to 300 oC. The direct formation of TiO2 nanoparticles on CNT showed good photocatalytic properties without further heat treatment. As the photocatalytic performance of TiO2 is driven only by UV irradiation, the second part of the study is on the fabrication of GaN:ZnO compound which can absorb visible light to generate hydrogen by water splitting. ZnGa2O4 compound was first prepared by a refluxing method, and the as-prepared ZnGa2O4 compound was then nitridized to form GaN:ZnO compound. The sample showed good efficiency of photocatalysis under visible light irradiation. Besides, the Ga2O3 and ZnO nanolaminate was prepared by plasma-enhanced ALD, and it was subsequently nitridized to form GaN:ZnO compound. In comparison to the refluxing method, the Ga to Zn ratio in the laminate fabricated by PEALD can be precisely controlled, which offers good potential for application in water splitting.