3D flower-like Ni doped CeO2 based gas sensor for H2S detection and its sensitive mechanism

Real time detection of H2S has been a hot topic and problem to be solved in recent years. Here, Ni doped CeO2 based MEMS gas sensors with high sensitivity, selectivity, stability, moisture resistance and reliable fabrication potency for detection of H2S have been developed. The sensors can quantitatively detect H2S on ppb level. The response can reach 3.1 (without obvious change within 40 days from 20 to 90 RH%) when exposed to 500 ppb H2S gas at its optimal operation temperature 200 ºC, and the response and recovery time is only 8 s and 13 s respectively. Furthermore, it displayed a lower detection limit (LOD) down to 10 ppb H2S. The enhanced sensing performance of the samples is confirmed as the increase of oxygen vacancies and catalytic role in oxidation of H2S, and their sensing mechanism was revealed by DFT calculation and in situ experiments. This work offers an insight to CeO2 based materials for highly sensitive gas sensors.