Heterovalent Y-doping MOF-derived core-shell nanocages sensors for highly sensitive room-temperature NH3 detection

Metal oxides derived from metal-organic frameworks (MOFs) have garnered significant attention for gas sensing owing to their superior properties and unique architectures. Doping is an effective strategy for enhancing gas-sensing capabilities. In this study, core–shell–structured Y-doped ZnO nanocages are synthesized via a two-step ZIF-8-templated calcination strategy. Material characterizations reveal that Zn and O are uniformly distributed and highly enriched within the core and shell layers, whereas the distribution of Y within the cavity establishes a highly conductive network throughout the nanocage. The 4Y-ZnO sensor demonstrate competitive room-temperature ammonia-sensing performance; it yields a high response of 602 toward 500 ppm NH 3 with satisfactory selectivity and a detection limit of 0.64 ppm. Mechanistic investigations reveal that Y doping promotes oxygen-vacancy formation, thus enhancing the adsorption of the target gas to amplify gas-sensing reactions, whereas the inherited core–shell architecture provides a substantially enlarged surface area for efficient gas diffusion. Density functional theory (DFT) calculations confirm that Y doping effectively enhances charge transfer and modulates the surface electronic structure, thus promoteing selective NH 3 adsorption and supporting the experimentally observed high sensitivity and selectivity. In this study, high-performance MOF-derived gas sensors are designed through synergistic structural and compositional optimization.