Tailoring the Electric Field Gradient in Cu‐Based Bimetallic Catalyst to Boost the Product Selectivity for CO 2 Electroreduction

The product selectivity of Cu‐based catalysts relates to a great extent to the electron localization at active sites in the electrochemical CO 2 reduction reaction (CO 2 RR). While internal electric field engineering offers a pathway to modulate Cu's electronic structure, the quantitative correlation between field intensity and CO 2 RR performance remains unexplored. This work systematically investigates gradient electric field effects in Cu‐based bimetallic systems, contrasting conventional electron‐withdrawing metals (Ag/Au) with electron‐donating counterparts. Indeed, guided by the theoretical calculations, the cost‐effective In, Fe, and Ni metals, which donate electrons to Cu interface, were integrated into Cu via single‐step co‐reduction. It achieves distinct selectivity at > 100 mA cm −2 with Cu‐In, delivering 87% CO Faradaic efficiency (FE), whereas Cu‐Fe/Ni shifts toward HCOOH (FE ~40%). In situ Raman spectroscopy characterization and density functional theory (DFT) calculations confirm that field‐regulated electron localization governs CO 2 adsorption and conversion pathways. This mechanistic insight establishes internal electric field optimization as a critical strategy for tuning Cu‐based bimetallic catalysts in CO 2 RR.