Enhanced formaldehyde gas sensing properties of ZnO nanosheets modified with graphene

In this study, pure ZnO (ZnO-1, ZnO-2) with two different morphologies, and graphene doped ZnO-2 (G-ZnO-2) were synthesized using a simple hydrothermal process at 150 °C. The formaldehyde gas sensing performance of the G-ZnO-2 composite, synthesized by an in-situ method was investigated. The morphologies and the structures of the nanomaterials were characterized by X-ray diffraction, field emission scanning electronic microscopy, and transmission electron microscopy. The experimental results indicate that the G-ZnO-2 based sensor exhibits unique advantages for the sensing of formaldehyde gas at concentrations in the range of 2 to 2000 ppm, such as fast response/recovery time and good selectivity, at an optimal working temperature of 200 °C. The improved sensing performance of the G-ZnO-2 composite indicates that the addition of graphene is effective in improving the formaldehyde sensing performance of ZnO-based sensors.