Boosting Singlet Oxygen Oxidation of Micropollutants at an Enzyme-like Bifunctional Single-Atom Catalyst Interface

Abstract

Singlet oxygen (¹O₂) plays a critical role in oxidation reactions, yet improving its reactivity with substrates remains a significant challenge. This study reports an enzyme-like bifunctional catalyst, Co–N₂O₂/NC, which can efficiently activate peroxymonosulfate (PMS) with high selectivity and nearly quantitatively generates ¹O₂ without producing other reactive oxygen species to achieve high reactivity. Notably, it significantly increases the bimolecular reaction rate constant between ¹O₂ and waterborne micropollutants, as demonstrated by the over 1400-fold enhancement in 4-chlorophenol (4-CP) oxidation compared to that in the bulk solution. Enzyme-like catalytic kinetics were observed, with N-sites of the N-doped carbon support serving for activating 4-CP via interfacial electronic interactions, while Co activates PMS to generate ¹O₂. The interfacial charge transfer lowers the energy barrier for ¹O₂ to approach the aromatic ring of 4-CP, which is the rate-limiting step in the oxygenation reaction. Our findings lay the foundation and offer guidance for designing catalysts that facilitate the efficient generation and use of ¹O₂, expanding its application to a broader range of oxidation processes.