A room-temperature ppb-level H2S sensor based on MoO3/CuO/g-C3N4 via a simple synthesis

The detection of H2S for biomarkers or special occasions often requires a lower detection limit. In this work, the ppb-level H2S sensor based on MoO3/CuO/g-C3N4 (MCC) was presented by a simple method. The characterized results show that MCC-2 possesses a larger specific surface area, and has more adsorbed oxygen and oxygen vacancy compared to MoO3 and MoO3/CuO. The gas-sensitive test results show that the response of the MCC-2 sensor to 1000 ppb H2S is up to 8.24 at room temperature, which is 1.31 times of MoO3/CuO (6.28). More importantly, the theoretical detection limit of the MCC-2 sensor is as low as 1.1 ppb, which is the lowest in the recent H2S sensor. In addition, the MCC-2 sensor has reliable repeatability, excellent selectivity to H2S, and still maintains a high response after continuous test for 5 weeks. Simultaneously, the MCC-2 sensor also keeps an outstanding response at high relative humidity. The excellent gas sensing properties are due to the larger specific surface area that can enable more gases to be adsorbed on the material surface. In addition, the oxygen vacancy reduces the energy required to adsorb the target gas and the formed heterojunctions by MoO3/CuO/g-C3N4 expedite carrier migration.