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

Abstract

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 π–π 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.