Enhanced gas sensing properties of ZnO/SnO2 hierarchical architectures by glucose-induced attachment

A simple glucose-assisted hydrothermal process has been developed to design complex and functional ZnO/SnO2 nanostructures. In this synthesis, the abundant hydroxyl groups of glucose can ligate with Zn2+ and Sn4+, and induce nucleation. Furthermore, the glucose molecules can form stacking templates to direct the oriented attachment of nanorods and nanoplates due to the [small pi]-[small pi] electron interactions between glucose ligands. The growth mechanism is studied by changing the synthesis conditions. It is found that the morphologies of ZnO/SnO2 greatly depend on the concentrations of glucose and sodium hydroxide, as well as the molar ratios between Zn2+ and Sn4+. The as-synthesized samples are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) techniques. In particular, gas sensing tests show that these ZnO/SnO2 nanostructures exhibit enhanced sensing properties to ethanol due to the formation of nano-heterojunctions and their unique morphologies.