Morphological evolution of Cu doped ZnO for enhancement of photocatalytic activity

Abstract

The structure, morphology and chemical doping in metal oxide are important factors that can influence on its photocatalytic activity. In this work, a facile and template free reflux method has been used to synthesize ZnO nanostructures for the morphology control of cubes, maize corn seeds, and rods at low temperature. The photocatalytic activity of ZnO with different morphology was evaluated towards degradation of methyl orange under UV light illumination. Among all the morphology controlled ZnO, the maize corn seed shaped ZnO shows the superior photocatalytic activity. Moreover, the influence of Cu contents on the structural, optical, and photocatalytic activity of ZnO maize corn seed was also investigated systematically. The photocatalytic experiment towards the degradation of methyl orange revealed that the 0.5 mol% Cu doped ZnO exhibits 3.5 fold higher photocatalytic activity than pure corn seed shaped ZnO. The enhancement of photocatalytic activity by Cu ions substituting in ZnO lattices is attributed to synergetic effect of Cu and ZnO, increase the separation of photogenerated electron-hole pairs, oxygen vacancy, decrease in crystallite size and the higher surface to volume ratio. Based on scavengers test, it was found that both superoxide and hydroxyl radicals are mainly actives species involved for the degradation of methyl orange.