Novel approaches for highly selective, room-temperature gas sensors based on atomically dispersed non-precious metals

Abstract

Atomically dispersed (AD) materials have incredible catalytic ability and offer atom economy with 100% metal utilization during catalytic reactions. Herein, we report the first attempt to synthesize AD FeNC materials for use as highly selective, room-temperature gas sensors. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM), extended X-ray absorption fine structure (EXAFS) spectroscopy, and Mössbauer spectroscopy characterization methods confirm the existence of atomically dispersed Fe with an FeN₄ coordination. We demonstrate a room temperature, sensitive, and selective NO₂ gas sensor technology using this platform, offering significant advantages over existing technology. Density functional theory (DFT) calculations verify that electrons are transferred to NO₂ from FeN₄ during NO₂ adsorption. Both DFT calculations and experiments also reveal that the barrier for NO₂ decomposition by AD FeNC is 0.73 eV, which is significantly lower than previously reported barriers (2.60–3.54 eV) in other materials. Such unique catalytic properties combined with a high surface affinity for NO₂ molecules enable AD FeNC gas sensors to have excellent selective NO₂ detection at room temperature. The method proposed here can inspire the use of AD materials to detect other gases and catalyze similar novel developments in the gas sensor industry.