Single-atom-engineered perovskite enables near-theoretical-rate hydroxyl radical electrogeneration

Abstract Electrochemical advanced oxidation that directly activates O 2 through the oxygen reduction reaction (ORR) to generate hydroxyl radicals (•OH) offers a sustainable strategy for degrading persistent organic pollutants. However, prevailing approaches typically rely on a stepwise process involving the 2e⁻ ORR to produce H 2 O 2 followed by 1e⁻ activation. High barriers associated with intermediate desorption and inter-site transfer consequently limit the •OH yield. Here, we construct a single-active-site architecture in the perovskite oxide Pr 1.0 Sr 1.0 Fe 0.5 Zn 0.25 Mo 0.25 O 4-δ (PSFZM) that enables a direct three-electron ORR pathway for efficient •OH generation. The Zn δ ⁺ single active center selectively stabilizes *OOH and *H 2 O 2 through weak orbital interactions, while an adjacent Mo atom polarizes the O atoms of adsorbed H 2 O 2 , promoting cleavage of the peroxide bond at the active site. This strategy avoids intermediate desorption and migration, enabling continuous proton-coupled electron transfer. The catalyst achieves a •OH production rate of 821 μmol h⁻ 1 and an O 2 utilization of 37.7%, metrics competitive with previously reported systems. In a membrane-free flow cell that uses gaseous O 2 directly, the •OH generation efficiency reaches 64.7%. By combining atomic-level catalyst design with reactor engineering, this work establishes a scalable platform for sustainable wastewater treatment.