Stable tensile-strained palladium hydride nanozymes with specifically enhanced peroxidase-like activity for intelligent glucose detection

While nanozymes with peroxidase (POD)-like activity hold promise as alternatives to natural enzymes in glucose colorimetric assays, most are hindered by their inherent oxidase (OXD)-like activity, which produces significant background signals that interfere with accurate detection. In this study, we discovered that the stably incorporating hydrogen atoms into the Pd lattice effectively enhances the POD-like activity of Pd nanozymes while concurrently reducing their OXD-like activity. The specific enhancement of POD-like activity for PdH nanozymes are attributed to tensile strain effects and resulting changes in their electronic structure. On the one hand, hydrogen intercalation into the Pd lattice induces substantially enhanced absorption and a lowered energy barrier for H₂O₂ activation, thereby significantly boosting POD-like activity by catalytically generating more hydroxyl radicals (·OH). On the other hand, lattice expansion in PdH nanozymes weakens the Pd–O₂ interaction, as it exceeds the optimal range for bridging O₂ adsorption. This impairs O₂ activation and hinders H₂O desorption during the OXD-like cycle. Based on these findings, a cascade sensing system based on PdH NCs was constructed, achieving sensitive and accurate colorimetric detection of glucose with a low detection limit. Moreover, this sensing platform demonstrates practical feasibility in detecting real serum and urine samples. This work not only provides a promising alternative to natural enzymes for sensitive and accurate biosensing of glycometabolic diseases, but also offers a tensile-strained-adjusted strategy for concurrently optimizing the activity and specificity of nanozymes.