Plasmon-Enhanced CH Generation in the CO Electroreduction Reaction on a CuPd Tandem Catalyst.

Electrocatalysis enables the conversion of CO into value-added fuels and chemicals, offering a sustainable solution for greenhouse gas mitigation. However, achieving high selectivity for C2 products like ethylene (CH) remains challenging due to competing C1 pathways and complex multielectron processes. Here, we demonstrate that plasmon resonances can selectively enhance the electroreduction of CO to CH by 27.0% on a CuPd catalyst under LED illumination (625 nm) at -1.3 V. Photocurrent response, 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 CH 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.