Ultrasensitive ppb-level H₂S gas sensor at room temperature based on WO₃/rGO hybrids

Gas sensors with high performance and low energy consumption are necessary for system integration in the environment monitoring of explosives. High-performance room-temperature hydrogen sulfide (H₂S) gas sensors were fabricated based on the hybrids of tungsten oxide (WO₃)/reduced graphene oxide (rGO). WO₃ nanocubes modified with different contents of rGO were synthesized by acid-based hydrothermal method. The optimal amount of rGO in the composite is 5 wt%, at which the room-temperature operating sensor presents the highest sensitivity of approximately 32.7 to 500 ppb H₂S, a fast recovery time of ~ 180 s, as well as an excellent sensing selectivity. The overall improvement in sensing performances demonstrated an important progress made in H₂S sensor fabrication for portable and real-time gas detection. The improved gas-sensing performance is attributed to the large specific surface area of the WO₃ nanocubes, the formation of WO₃/rGO heterojunctions, and the enhanced electron transfer efficiency.