High O2 tolerant metal-based catalysts for selective H2O2 reduction by constructing an ultra-thin oxide passivation layer.

The design and development of highly selective and sensitive methods for the electrochemical reduction and detection of hydrogen peroxide (H₂O₂) are of paramount importance, as H₂O₂ is closely associated with various disease biomarkers. Although frequently used H₂O₂ reduction catalysts can avoid influence from many interferences, their inability to simultaneously prevent the oxygen reduction reaction (ORR) during H₂O₂ detection presents a significant limitation. In this study, a selective sensing platform based on noble metal/tin oxide (NM/SnO₂) was fabricated by depositing an ultra-thin passivation layer of SnO₂ onto noble metal catalysts using atomic layer deposition (ALD) technology. The amorphous SnO₂ layer effectively inhibits O₂ diffusion to the metal/oxide interface, endowing NM/SnO₂ with remarkable tolerance to the ORR and enhancing its selectivity and performance in the electrochemical detection of H₂O₂. Based on this sensing platform, a series of bioassay systems were developed that can accurately detect multiple biomarkers, including glucose, lactate, and choline. This work provides a straightforward and controllable strategy for fabricating ORR-tolerant H₂O₂ reduction catalysts, with promising applications in electroanalysis and clinical diagnosis.