Controllable fabrication and photocatalytic activity of ZnO nanobelt arrays

Well-aligned single-crystalline ZnO nanobelt arrays were fabricated on a Si wafer by a carbothermal reduction route with the assistance of a SnO2/Sn species. The as-prepared ZnO nanobelt arrays were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, UV-vis spectroscopy, and photoluminescence spectroscopy. The photocatalytic activity for methyl orange on the ZnO nanobelt arrays was also investigated under UV irradiation. The ZnO nanobelts are several tens of nanometers in thickness, 100-500 nm in width, and have a length of up to several micrometers. It has been found that the ZnO nanobelt arrays form on a substrate only when the thickness of the SnO2 coating is less than 100 nm. The rod-/comb-like ZnO nanostructures and the ZnO film can be obtained by increasing the SnO2 loading or the temperature, respectively, The ZnO nanobelts grow from the active surface at the nanobelt root via a vapor-liquid-solid mechanism. The ZnO nanobelt arrays show strong emission both in the UV and in the green region. The as-prepared ZnO nanobelt arrays have a good photocatalytic property, as evidenced by the result that over 94% of the methyl orange decomposed over the ZnO nanobelt arrays, which is better than the as-prepared ZnO film and the rod-/comb-like ZnO nanostructures under identical conditions.