UV-activated CuO nanospheres modified with rGO nanosheets for ppb-level detection of NO2 gas at room temperature

Monitoring and reducing NO2 pollution at room temperature is indispensable for human survival. Thus, we propose a light-activated route (UV light, 100 mW/cm2) to realize a high-performance NO2 detection based on CuO/rGO gas sensor. The CuO/rGO sensor under UV light illumination exhibits a high response of 22.18–100 ppm NO2 at 23 ℃, which is approximately 1.36 times of the CuO/rGO sensor and 2.31 times of the CuO sensor under dark, respectively. Meanwhile, under UV light illumination, the CuO/rGO sensor has a fast response/recovery speed of 10.9/30.9 s to 20 ppm NO2 at 23 ℃, which is obviously better than that under dark. Moreover, the light-activated CuO/rGO sensor has excellent repeatability, selectivity, ultra-low detection limit (50 ppb) and long-term stability. The significantly appealing gas-sensing performance of CuO/rGO sensor is mainly ascribed to the mesoporous structure, high specific surface area and plentiful oxygen vacancy of CuO/rGO nanocomposites. More attractively, the photo-generated carriers and formed heterojunction also greatly improve the carrier migration in the context of the NO2/CuO/rGO interaction, enhancing the gas-sensing performance of gas sensor. Our work will provide insight in utilizing light illumination to realize ultrasensitive and room-temperature detection of ppb-level NO2 gas.