Dependence of photocatalytic activity on structural and optical properties of nanocrystalline ZnO powders

Nanocrystalline ZnO powders were prepared from cetyltrimethylammonium bromide (CTAB)-modified NaOH, NH4OH and (CH2)6N4 solutions. The calcined ZnO powders exhibited a hexagonal structure without any secondary phase. Different shapes of ZnO powders were formed depending on CTAB concentration and type of precipitating agent. As (CH2)6N4 solution was used, rod-like ZnO structure was changed to a spherical shape when CTAB concentration was increased. The widest Eg value of approximately 3.23 eV was obtained from the sample containing the lowest defect concentration. The decolorization efficiency was higher than 90% after irradiating for 90 min and the sample with higher Eg value showed higher decolorization efficiency.