Visualizing Labor Division in Oxygen Electrocatalysis: Fully Exposed Ni Clusters Enabling Dual‐Site Catalysis via Asymmetric Atomic Bridging

ABSTRACT

Fully exposed metal cluster catalysts combine the atomic precision of single‐atom catalysts with the multi‐site reactivity of nanomaterials; however, achieving both structural stability and site‐specific bifunctionality remains challenging. Herein, we report a Janus‐type bifunctional catalyst comprising fully exposed atomic‐layered nickel clusters anchored on Co ₂ P nanocrystals (Ni _AC ‐Co ₂ P), demonstrating excellent oxygen reduction/evolution reaction (ORR/OER) performance. Leveraging an electronic metal‐support interaction, interfacial charge redistribution fine‐tunes the d‐band centers, optimizes intermediate adsorption and promotes dual‐site catalysis. Theoretical calculations show the Ni‐P‐Co bridge lowers the *OOH formation barrier in ORR (half‐wave potential of 0.90 V), while Ni clusters facilitate *O to *OOH conversion in OER (overpotential of 260 mV), enabling efficient four‐electron kinetics via spatially decoupled dual‐site cooperation. Operando x‐ray absorption spectroscopy further confirms this mechanism, revealing Ni sites at the Ni‐P‐Co bridge undergo reversible Ni‐P coordination modulation and transient Ni‐O bond formation during ORR, whereas Ni‐Ni clusters transform into NiOOH‐like species to drive OER. Importantly, Ni _AC ‐Co ₂ P‐assembled Zn‐air battery delivers a peak power density of 199.8 mW cm ⁻² and stable cycling performance exceeding 1400 h (approximately 4200 cycles). This work introduces a dual‐site catalysis paradigm in transition metal phosphide‐supported, fully exposed cluster catalysts, providing a robust strategy for designing multifunctional catalysts for energy conversion.