Oxygen Vacancy‐Mediated Catalysts toward Selective H₂O₂ Reduction in Cellular Environment

Abstract

Abstract Abnormal hydrogen peroxide (H 2 O 2 ) levels in the cellular environment are closely related to cell dysfunction and serious diseases. Thus, selective and sensitive H 2 O 2 detections are urgently needed for clinical diagnosis and therapy. Herein, via surface defect engineering, an oxygen‐tolerant electrocatalyst based on tin oxide for selective H 2 O 2 reduction and detection with exceptional stability and activity is designed and developed. When introduced at an appropriate level (≈5.3%), surface oxygen vacancies help lower the charge transfer resistance for enhancing the H 2 O 2 reduction reaction, while maintain the weak oxygen (O 2 ) adsorption, which enables a constant H 2 O 2 reduction (sensing) response in the electrolyte at variable oxygen levels. Moreover, the tin oxide‐based assay system exhibits outstanding stability over a wide pH range of 4–9, as well as selectivity in the presence of interferent endogenous and exogenous electroactive species, which is suitable for trace H 2 O 2 monitoring secreted from NB4 cells, a model cancer cell. The oxygen vacancy‐mediated tin oxide achieves the highest stability as well as high selectivity compared to reported electrochemical probes for specific H 2 O 2 detection in biological environments, with the potential for biological and biomedical applications.