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

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.