Atomically dispersed noble-metal-sensitized semiconductor metal oxides for chemiresistive gas sensing

Semiconductor metal oxide (SMO) gas sensors have long been recognized for their low cost, facile fabrication, and high stability, yet conventional designs suffer from poor selectivity and limited sensitivity at trace gas levels. Recent advances in atomically dispersed noble‑metal sensitized SMO materials have increasingly enabled the transition from heterogeneous nanoparticle interfaces to more atomically defined sensitizer sites, offering enhanced atomic utilization and improved control over electronic modulation. These atomically dispersed noble metals create clear coordination environments that tailor gas adsorption, activation, and charge‑transfer dynamics, thereby enabling ultrahigh sensitivity, rapid response speed, and excellent selectivity. This review summarizes recent progress in the synthesis, characterization, and sensing applications of atomically dispersed noble‑metal sensitized SMOs, spanning hydrogen, carbon monoxide, nitrogen oxides, sulfur‑containing gases, and some volatile organic compounds. Finally, it highlights key challenges and future directions toward mechanism‑driven design, scalable fabrication, and integration with microelectromechanical systems for next‑generation, high-performance gas sensing technologies.