Overcoming the Sensitivity‐Selectivity Trade‐Off in Chemiresistive CO Sensors Through a Single‐Atom Pt‐Activated Lattice Oxygen Strategy

ABSTRACT The sensitivity‐selectivity trade‐off remains a fundamental challenge in chemiresistive carbon monoxide (CO) sensing, as enhanced surface redox activity often promotes non‐specific reactions with chemically similar interferents. Single‐atom noble‐metal sensitizers improve adsorption selectivity but suffer from ultra‐low loading, limiting sensing sensitivity. Here, we report a single‐atom Pt‐activated lattice oxygen strategy that simultaneously enhances sensitivity and selectivity by engaging lattice oxygen in CO sensing. By incorporating single‐atom Pt into the SnO 2 lattice, the sensor achieves a ∼15‐fold sensitivity enhancement relative to SnO 2 , excellent selectivity against common interfering gases, and a sensing response even under oxygen‐deficient conditions. Spectroscopic analyses combined with first‐principles calculations reveal a dual functional role of lattice‐anchored Pt: single‐atom Pt establishes preferential CO adsorption sites via electronic interaction with CO, while its strong coupling with the Sn─O framework upshifts the O 2p band center, lowers the activation barrier for lattice‐oxygen‐mediated CO oxidation, and thereby enhances sensing sensitivity. Integration of the sensor into a portable CO breath analyzer further demonstrates over 8‐fold higher sensitivity than a commercial sensor under simulated exhalation conditions. This work establishes single‐atom Pt‐activated lattice oxygen strategy as an effective approach to overcome the sensitivity‐selectivity trade‐off in CO sensing.