Achieving Switchable CO/H₂ Detection with Selectivity-Tunable SnO₂–Co₃O₄ Sensors

The limited selectivity of metal oxide semiconductor (MOS) sensors poses a persistent challenge to their practical implementation. Here, we demonstrate switchable CO/H 2 detection through tailored gas adsorption properties enabled by compositional engineering of SnO 2 –Co 3 O 4 nanocomposites. To address gas mixture quantification, we developed a dual-functional sensor array featuring distinct SnO 2 –Co 3 O 4 sensing units optimized for H 2 and CO detection, respectively. This architecture, when integrated with gradient boosting regression (GBR) algorithms, achieves simultaneous concentration prediction of both analytes in complex gaseous environments. Furthermore, a comprehensive investigation combining experimental characterization and first-principles calculations reveals the underlying mechanism governing selectivity modulation in these heterostructures. The work offers critical experimental insights and theoretical foundations for rational design of high-selectivity gas-sensing platforms.