Preparation of MOF-derived ZnO/Co3O4 nanocages and their sensing performance toward H2S

We report a type of micro-electro-mechanical system (MEMS) H2S gas sensors with excellent sensing performance at the ppb level (lowest detection limit is 5 ppb). The sensors were fabricated with ZnO/Co3O4 sensing materials derived from Zn/Co-MOFs by annealing at a suitable temperature of 500 & DEG;C. ZnO/Co3O4-500 exhibits the highest response when exposed to 10 ppb H2S gas at 120 & DEG;C, and the response/recovery times are 10 s/21 s. Moreover, it exhibits outstanding selectivity, long-term stability (retained 95% response after 45 days), and moisture resistance (only a minor fluctuation of 2% even at 90% RH). This can be ascribed to the fact that ZnO/Co3O4-500 has regular morphology, abundant oxygen vacancies (52.8%) and high specific surface area (96.5 m(2) g(-1)). This work provides not only a high performance H2S MEMS gas sensor but also a systematic study of the effect of the annealing temperature on the sensing performance of ZnO/Co3O4 sensing materials derived from bimetal organic frameworks.

Automated summary

We have developed a highly sensitive H2S gas sensor based on a micro-electro-mechanical system (MEMS) with a ppb level detection limit (as low as 5 ppb). The sensor utilizes ZnO/Co3O4 sensing materials derived from Zn/Co-MOFs through annealing at 500°C. The ZnO/Co3O4-500 sensor shows the highest response when exposed to 10 ppb H2S gas at 120°C, and it exhibits excellent selectivity, long-term stability, and moisture resistance due to its unique morphology and properties.