It all depends on the ingredients: The physicochemical properties of (Ga1−xZnx)(N1−xOx), including its particle size, are dependent on the particle size of the ZnO precursor. The relationship between the physicochemical properties and photocatalytic performance of (Ga1−xZnx)(N1−xOx) for overall water splitting under visible light was investigated to identify suitable starting materials of the catalyst.
The influence of starting materials on the physicochemical and photocatalytic properties of (Ga1−xZnx)(N1−xOx) were investigated in an attempt to optimize the preparation conditions. The catalyst was successfully prepared by nitriding a starting mixture of ZnO and Ga2O3. A mixture of metallic zinc and GaN, however, did not afford the desired compound. The crystallinity, surface area, composition, and absorption characteristics of the resultant (Ga1−xZnx)(N1−xOx) solid solution are found to be dependent on the morphology of ZnO but largely insensitive to the choice of Ga2O3 polymorph. The use of coarser-grained ZnO results in a coarser-grained catalyst with elevated zinc and oxygen content and reduced uniformity in composition and crystallinity. The results demonstrate the importance of selecting appropriate ZnO and Ga2O3 starting materials for maximizing the photocatalytic activity of (Ga1−xZnx)(N1−xOx) for overall water splitting under visible light.