UV-activated efficient formaldehyde gas sensor based on cauliflower-like graphene-modified In-doped ZnO at room temperature

So far, for photoelectric metal oxide semiconductor gas sensors, it is a huge bottleneck to achieve high response performance and low detection limit of formaldehyde at room temperature. This work introduced the synthesis of cauliflower-like graphene-modified In-doped ZnO (GR/In-ZnO) composites via a facile one-pot method with a large comparative surface area for low-concentration formaldehyde sensing at room temperature. GR/In-ZnO-300 showed the highest response to 10 ppm formaldehyde, up to 1891%, which was 12 times that of In-ZnO-300. In addition, the theoretical detection limit of GR/In-ZnO-300 was as low as 13 ppb, and the response at this concentration was 137%. Through the characterization of Surface Photovoltage (SPV), Transient Photovoltage (TPV), Surface Photocurrent (SPC), X-ray Photoelectron Spectroscopy (XPS), and nitrogen gas adsorption isotherms, good formaldehyde sensing performance of GR/In-ZnO-300 was attributed to the excellent separation and transmission capacity of photogenerated carriers, the high specific surface area (109.2 m2/g), and abundant oxygen defects on the surface. This work provides a feasible strategy for the design of low-concentration formaldehyde sensing materials with a rapid response at room temperature. •Cauliflower-like GR/In-ZnO is fabricated via a facile one-pot method.•GR/In-ZnO-300 exhibits high response and low detection limit at room temperature.•Excellent gas sensing performance is explained by SPV, TPV, and SPC spectrum.•GR promotes carrier migration and provides a large specific surface area and abundant oxygen vacancies.