MOF-Derived Co3O4 Dodecahedrons with Abundant Active Co3+ for CH4 Gas Sensing at Room Temperature.

Gas sensors based on metal oxide semiconductors (MOS) have attracted significant attention in monitoring of methane emission and leakage monitoring due to their high sensitivity, fast response time, simple structure and low cost. However, the high power consumption caused by long-term high-temperature operation of MOS sensors restricts their application in mobile and portable devices. In this study, MOF-derived Co3O4 dodecahedrons for low-concentration methane detection at room temperature was prepared using Zeolitic Imidazolate Framework-67 (ZIF-67) as a template and with various calcination temperatures. Among them, the Co3O4-350 calcined at 350 °C exhibited the optimal CH4 sensing performance at room temperature, with a response of Rg/Ra = 1.53 to 2000 ppm CH4. This enhanced gas sensing performance is attributed to the highest Co3+ proportions and the largest specific surface area in Co3O4-350 nanomaterials, which provided more active sites for gas adsorption and reaction. To address the challenge of slow response speed and irrecoverability during CH4 detection at room temperature, the Co3O4 nanomaterials were printed onto a micro-heater plate (MHP) to form a MEMS gas sensor. By introducing a pulse heating mode to the MEMS sensor, the response and recovery time were significantly reduced to 26 s and 21 s, respectively. This enhancement improves both the efficiency and reliability of the MEMS gas sensor for early-stage detection of CH4 leaks in various industrial applications.