Tailoring the Electric Field Gradient in Cu-Based Bimetallic Catalyst to Boost the Product Selectivity for CO₂...

The product selectivity of Cu-based catalysts relates to a great extent to the electron localization at active sites in the electrochemical CO₂ reduction reaction (CO₂RR). While internal electric field engineering offers a pathway to modulate Cu's electronic structure, the quantitative correlation between field intensity and CO₂RR 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 CO₂ adsorption and conversion pathways. This mechanistic insight establishes internal electric field optimization as a critical strategy for tuning Cu-based bimetallic catalysts in CO₂RR.