Charge-Separated Pdδ−–Cuδ+ Atom Pairs Promote CO2 Reduction to C2

Positively charged Cu sites have been confirmed to significantly promote the production of multicarbon (C2) products from an electrochemical CO2 reduction reaction (CO2RR). However, the positively charged Cu has difficulty in existing under a strong negative bias. In this work, we design a Pdδ--Cu3N catalyst containing charge-separated Pdδ--Cuδ+ atom pair that can stabilize the Cuδ+ sites. In situ characterizations and density functional theory reveal that the first reported negatively charged Pdδ- sites exhibited a superior CO binding capacity together with the adjacent Cuδ+ sites, synergistically promoting the CO dimerization process to produce C2 products. As a result, we achieve a 14-fold increase in the C2 product Faradaic efficiency (FE) on Pdδ--Cu3N, from 5.6% to 78.2%. This work provides a new strategy for synthesizing negative valence atom-pair catalysts and an atomic-level modulation approach of unstable Cuδ+ sites in the CO2RR.