Enhanced photocatalytic performance of nanosized coupled ZnO/SnO2 photocatalysts for methyl orange degradation

Nanosized coupled ZnO/SnO2 photocatalysts with different Sn contents were prepared using the coprecipitation method, and characterized by X-ray diffraction, specific surface area and UV-Vis diffuse reflectance spectroscopy. The phases, mean grain sizes and band gap energy of the coupled ZnO/SnO2 photocatalysts varied with the Sn contents and the calcination temperatures. The photocatalytic activities of the coupled ZnO/SnO2 photocatalysts, evaluated using the photodegradation of methyl orange as a probe reaction, were also found to be related to the calcination temperatures and the Sn contents. The photocatalytic activities of the coupled ZnO/SnO2 photocatalysts decreased with the increasing calcination temperatures. The maximum photocatalytic activity of the coupled ZnO/SnO2 photocatalyst, which is about 1.3 times the photocatalytic activity of ZnO and 21.3 times that of SnO2, was observed with a Sn content of 33.3 mol% under calcination at 500 °C for 10 h. The enhancement of the photocatalytic activity might arise from the hetero-junctions ZnO/SnO2 in the coupled oxides. The photo-stability of the ZnO/SnO2 photocatalyst was also studied.