Dynamic Heterovalent Dual-Cu Sites for O═O Cleavage in Electrocatalytic Oxygen Reduction Reaction.

Activation and cleavage of the inert O═O bond represent a central challenge in energy electrochemistry. Here, the Cu dual-atom catalyst (Cu-DAC) is constructed via bottom-up pre-coordination assembly and post-encapsulation pyrolysis. The resulting Cu-DAC features a well-defined Cu-Cu distance (∼3.31 Å) with switchable Cu1+/Cu2+ states, enabling dynamic dual-site coordination with O2. Cu-DAC achieves 0.87 VRHE half-wave potential for oxygen reduction reaction (ORR), a near-unity 4e- selectivity, and outstanding stability. Multiple operando spectroscopic characterizations and ab initio dynamic simulations (AIMD) reveal that the dynamic heterovalent [Cu1+─O─O· -─Cu2+] unit elongates the O-O bond and promotes its cleavage via dual-site confinement and electron donation. By specifically elucidating how these dual-atom sites dynamically evolve to facilitate O─O bond cleavage, we provide vital atomic-level principles for the rational design of dynamically active catalysts.