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 pi 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.