Bimetallic MOF-Derived NiO/In2O3 Heterojunctions for NO2 Sensing

Low-temperature (including room-temperature) gas sensors are crucial for energy-efficient and safe detection applications. In this study, we report the synthesis of In2O3-sensitized NiO nanoparticles (NPs) for NO2 detection. The NiO/In2O3 hybrid materials were obtained by pyrolysis of Ni/In bimetallic metal–organic framework (MOF) nanosheets (NSs) fabricated through ultrasonic synthesis and cation exchange. Gas sensing tests revealed that the In2O3 sensitization significantly enhances the NO2 sensing performance of NiO, enabling a response of 1.5 at room temperature (RT) and an optimal response at 100 °C. The NiO/In2O3 sensor demonstrates enhanced selectivity toward NO2, an ultra-low detection limit (41 ppb), and long-term stability. This study presents an effective MOF-derived route for developing high-performance low-power gas sensors.