Synthesis and surface modification of ZnO nanoparticles
ZnO precursor was prepared by direct precipitation from zinc acetate and ammonium carbonate. ZnO nanoparticles were synthesized by calcination of the precursor at 450 [degree sign]C for 3 h and the calcination after the heterogeneous azeotropic distillation of the precursor, respectively. The synthesized ZnO nanoparticles were characterized by FT-IR, XRD and TEM. It is concluded that the heterogeneous azeotropic distillation of the precursor effectively reduced the formation of hard agglomerates. The surface modification of synthesized ZnO nanoparticles was conducted by capping with oleic acid, and the existence of organic layer can be confirmed by the FT-IR spectra. The lipophilic degree of surface modified ZnO nanoparticles was measured. The ZnO nanoparticle surface was also modified by SiO2 coating. The FT-IR spectrum and XPS clearly showed the formation of an interfacial chemical bond between ZnO and SiO2. In addition, photocatalytic degradation of methyl orange in aqueous solution was performed using ZnO nanoparticles or ZnO/SiO2 nanoparticles as photocatalyst, respectively. The results showed that the ZnO/SiO2 nanoparticles have reduced catalytic activity than that of ZnO nanoparticles.