▎ 摘　　要

Sensitive detection of trace nitrogen dioxide (NO2) gas at room temperature is of urgent necessity in the fields of healthcare and environment monitoring. To achieve this goal, we report on a porous composite film featuring reduced graphene oxide (rGO) nanosheets as the template platform of nanostructured cuprous oxide (Cu2O) nanowires and nanoparticles via a hydrothermal method. The sensor performance was investigated in terms of sensing response, optimal operation temperature, repeatability, long-term stability, selectivity and humidity effect on NO2 sensing. The sensor response achieved 0.66 towards 50 ppb NO2 gas with a full recovery at room temperature (25 degrees C +/- 2 degrees C), which was among the best cases of Cu2O-related NO2 detection concerning sensor response and operation temperature. Moreover, a modest repeatability, stability, selectivity as well as a negligible humidity effect on NO2 sensing were exhibited. A mass of interspaces existing within nanostructured composites as well as the synergistic effect between rGO and Cu2O materials endowed the sensing layer with favorable gas accessibility and sufficient gas-solid interaction. Simultaneously, highly conductive rGO nanosheets facilitated an effective electron transfer and collection. In brief, the asprepared rGO/Cu2O sensors showed a competitive room temperature detection capability for ppb-level NO2 gas, providing a vast potential in the future applications such as the real-time monitoring of ultralow emission.