Curvature‐Engineered Steering of Oxygen Electroreduction Pathways on Single‐Atom Catalysts

ABSTRACT Single‐atom catalysts (SACs) are a promising class of electrochemical oxygen reduction reaction (ORR) catalysts, enabling either a four‐electron (4e – ) pathway for energy conversion or a two‐electron (2e – ) pathway for H 2 O 2 production. However, the precise control and optimization of the ORR pathway remain challenging due to the lack of strategies for fine‐tuning the SACs coordination structures. Herein, we developed a curvature engineering strategy that enables, for the first time, continuous steering of the ORR pathway from 2e – to 4e – over Cu‐based SACs. Through theoretical calculations and in‐situ spectroscopy, we revealed the essential mechanism by which active‐site tensile strain and interfacial water restructuring, induced by carbon nanotubes with varying curvature, jointly govern ORR activity and selectivity. The Cu single‐atom sites on high‐curvature CNTs exhibit 4e – ORR performance comparable to that of Pt/C, while those on low‐curvature CNTs achieve up to 99.5% 2e – ORR selectivity. Proof‐of‐concept solid‐electrolyte electrolyzer equipped with Cu SACs demonstrates exceptional performance for H 2 O 2 electrosynthesis, achieving H 2 O 2 Faradaic efficiencies of 96.4% and 92.5% at 200 and 300 mA cm −2 , respectively, and sustaining >90% efficiency for over 100 h at a total current of 3 A. This work establishes curvature engineering as an ORR descriptor for precisely regulating SACs and designing advanced electrocatalysts.