▎ 摘　　要

We produced a graphene oxide (GO) based nitrogen dioxide (NO2) gas sensor with extremely low limit of detection (LOD), which is far below the WHO and EU annual standards. Based on the derived correlation among the band gap, adsorption energy, and sensing performance, we prepared semiconductive reduced GO (HGO) with simply modified acid washing process of traditional Hummers' method. HGO, prepared with dispersed state enables easy fabrication of sensing device by a simple drop casting process and showed great sensing performance when HGO showed band gap of semiconductor. This research is considered that opened a new route to preparing extremely sensitive NO2 gas sensors through very facile and cost effective processes. (C) 2019 Elsevier Ltd. All rights reserved.