Electrospray synthesis and photocatalytic activities of ZnO-SiO₂ composites particles

A new and rapid method for zinc oxide (ZnO) and ZnO-SiO₂ (ZS) composite particles by the simple electrospray method was reported. Free agglomeration and smaller particle size of ZS composite obtained with an increase in the applied voltage that correlates with the charge repulsion within the particles. The presence of silica inhibited the ZnO particles and crystal growth. The XRD and FTIR spectra indicated that silica covered the ZnO particles. Smaller ZS molar ratio with higher applied voltage had a significant role in minimizing the agglomeration of the particle production. This suggested a morphological control of the composite through electrospray. The results of the photocatalytic degradation of methylene blue (MB) in aqueous solution revealed that the presence of silica effectively inhibited the photocatalytic activity of ZnO particles in which the ZnO without and with silica had degradation rate 85% and 63%, respectively. The effect of silica amount to the ultraviolet (UV) shielding property of ZnO particles also examined.