Construction and enhanced low-temperature H2S-sensing performance of novel hierarchical CuO@WO3 nanocomposites

Novel hierarchical CuO@WO3 nanocomposites with various CuO contents (0–10 wt%) were synthesized by anchoring discrete CuO nanoparticles (CuO NPs) on WO3 nanoplates under a hydrothermal condition for low-temperature detection of H2S gas. In the CuO@WO3 nanocomposite, CuO NPs are uniformly distributed on WO3 nanoplates, forming a p-n CuO/WO3 heterojunction. The CuO@WO3 nanocomposites show highly sensitive to H2S gas at a low operating-temperature range (25–100 °C). The 5 wt%CuO@WO3 sensor shows a high response of 830 when exposed to a 10 ppm H2S gas at 100 °C. At even lower temperatures (e.g., 50 °C and 25 °C), the 5 wt%CuO@WO3 sensor shows an obvious response to 1 ppm H2S, and their response time is less than 3 min. In addition, the CuO@WO3 sensor exhibits a highly selective response to H2S, compared with SO2, CO, CH4, H2, and organic vapors, operating at 25–100 °C. The improvement of the CuO@WO3 sensor in H2S detection at a low operating temperature is ascribed to the unique hierarchical p-n heterojunctions formed between the CuO NPs and WO3 nanoplates.