Improvement of Ethanol Gas-Sensing Responses of ZnO–WO(3) Composite Nanorods through Annealing Induced Local Phase Transformation

In this study, ZnO–WO(3) composite nanorods were synthesized through a combination of hydrothermal growth and sputtering method. The structural analysis results revealed that the as-synthesized composite nanorods had a homogeneous coverage of WO(3) crystallite layer. Moreover, the ZnO–WO(3) composite nanorods were in a good crystallinity. Further post-annealed the composite nanorods in a hydrogen-containing atmosphere at 400 °C induced the local phase transformation between the ZnO and WO(3). The ZnO–WO(3) composite nanorods after annealing engendered the coexistence of ZnWO(4) and WO(3) phase in the shell layer which increased the potential barrier number at the interfacial contact region with ZnO. This further enhanced the ethanol gas-sensing response of the pristine ZnO–WO(3) composite nanorods. The experimental results herein demonstrated a proper thermal annealing procedure of the binary composite nanorods is a promising approach to modulate the gas-sensing behavior the binary oxide composite nanorods.