Plasmon-Enhanced C₂H₄ Generation in the CO₂ Electroreduction Reaction on a CuPd Tandem Catalyst

Electrocatalysis enables the conversion of CO₂ into value-added fuels and chemicals, offering a sustainable solution for greenhouse gas mitigation. However, achieving high selectivity for C2 products like ethylene (C₂H₄) remains challenging due to competing C1 pathways and complex multielectron processes. Here, we demonstrate that plasmon resonances can selectively enhance the electroreduction of CO₂ to C₂H₄ by 27.0% on a CuPd catalyst under LED illumination (625 nm) at -1.3 V_RHE. Photocurrent response, in situ FTIR spectroscopy, and COMSOL simulations reveal that plasmon-derived hot electrons and heating greatly facilitate *CO formation at the CuPd interface, which diffuses to the Cu surface for subsequent C-C coupling. DFT calculations show that the increased *CO coverage on the Cu sites reduces the energy barrier for C-C coupling, ultimately enhancing C₂H₄ generation. This work offers valuable mechanistic insights into plasmon-mediated electrocatalysis, guiding the development of more efficient plasmonic tandem electrocatalysts for future carbon recycling technologies.