Behavior Regulation of *CO over Self-Evolution Tandem Catalysts Under Tuned Interfacial Electric Field Boosts CO₂ Electroreduction

Tandem or self-evolution Cu-based catalysts effectively regulate *CO to promote the conversion of CO₂ electroreduction to multicarbon (C₂₊) products. DFT calculations reveal that the adsorption capacity of *CO varies under different interfacial electric field intensities for the Cu, Ag/Cu, Pd/Cu, and Au/Cu models. Accordingly, we design three kinds of self-evolution tandem catalysts and investigate the adsorption and migration behaviors of *CO under interfacial electric fields. Electrochemical CO₂ reduction test results indicate that the higher CO selectivity of Au/Cu is attributed to its weak *CO adsorption capacity, confirmed by in situ attenuated total reflection-infrared and in situ Raman. The low C₂₊ selectivity of Pd/Cu is owing to its high reaction energy barrier and low catalytic activity. In contrast, Ag/Cu achieves a high FE_C2+ of 89.2% and a partial current density (j_c2+) of 553.9 mA cm⁻² thanks to the low reaction energy barrier and moderate *CO adsorption capacity. COMSOL multiphysics simulations reveal that the effect of the interfacial electric field on *CO external migration could be neglected in the nanometer range. Although a strong interfacial electric field increases the energy barrier for internal migration of *CO, the enhanced adsorption capacity of *CO still dominates C–C coupling in the *CO-rich microenvironment over tandem catalysts.