▎ 摘　　要

Commercialization of a chemical sensor relies on the sensing performance, stability and selectivity for detecting gases at different environmental conditions. Here, we report ammonia sensors based on copper oxide (CuO) and reduced graphene oxide (rGO) nanocomposite with a hierarchical structure. The employed surfactant-free hydrothermal method for the sensing element synthesis is found to be efficient in yielding hierarchical nanoarchitectures. The synthesized CuO and rGO-CuO nanocomposite were characterized for structural, morphological, optical and surface adsorption properties. In order to understand the sensing properties, the printed sensors with pristine CuO and rGO-CuO composite were subjected to concentration, temperature and time-dependent ammonia sensing measurements. The rGO-CuO nanocomposite sensor showed an enhanced sensor response of 13 at room temperature (30 degrees C) and 30 at 300 degrees C, respectively which is a 10-fold increase as compared to pristine CuO based device. The selectivity experiments were carried out by exposing the sensor to ethanol, methanol, acetone, and ammonia. The sensor showed the highest response towards ammonia in comparison with other test gases. The observed sensing performance suggests the applicability of the present sensors to room temperature and elevated temperature operations. (C) 2019 Elsevier B.V. All rights reserved.