▎ 摘　　要

The fabrication of highly sensitive gas sensors that can monitor environmental toxic gases, such as nitrogen dioxide (NO2), which is one the most harmful gases to human health, attracts considerable attention. In this study, a hybrid structure composed of reduced graphene oxide (rGO) and a p-type NiO hierarchical structure (NiO-rGO) is fabricated using a facile solution process. The morphology and surface properties are analyzed by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The NO2 sensitivity is enhanced by the high surface to volume ratio of the NiO hierarchical structures as well as the enhanced charge transfer of NiO to rGO. The fabricated sensor with a hierarchical NiO and rGO hybrid structure exhibiting high sensitivity and selectivity at a low temperature (100 degrees C) with a rapid response time. (C) 2016 Elsevier Ltd. All rights reserved.