Asymmetric Electronic Modulation Accelerating Proton‐Coupled Electron Transfer and CO ₂ Reduction at Strongly Negative Potentials

Abstract

ABSTRACT Electrochemical CO 2 reduction to value‐added chemicals offers a sustainable route toward carbon neutrality under mild conditions. Yet, it faces an intrinsic proton‐electron imbalance at strongly negative potentials, where the hydrogen evolution reaction (HER) dominates, depletes interfacial protons, and severely compromises CO 2 reduction selectivity. Here, we report an asymmetric Ni–Fe dual‐atom electrocatalyst that restores efficient proton‐coupled electron transfer (PCET) through cross‐site synergy. Electron migration from Fe to Ni establishes a local asymmetric electric field that enhances CO 2 adsorption and induces molecular bending at Ni sites, thereby weakening the C═O bond. Simultaneously, electron‐deficient Fe sites exhibit moderated H adsorption, suppressing HER while serving as transient proton reservoirs for adjacent Ni centers. This spatially separated yet temporally synchronized PCET pathway accelerates the rate‐determining CO 2 → COOH step and sustains efficient CO 2 ‐to‐CO conversion under deeply cathodic conditions. Consequently, the Ni─Fe dual‐atom electrocatalyst maintains CO selectivity exceeding 95% across a wide potential window from −0.9 to −1.4 V and reaches 99.1% at −1.2 V, markedly outperforming monometallic analogues that exhibit volcano‐type selectivity decay due to unbalanced PCET‐HER kinetics. This work highlights asymmetric electronic modulation as an effective strategy to resolve the intrinsic PCET‐HER selectivity conflict in CO 2 reduction.