Synergistic ligand–photon interactions for enhanced CO2 electroreduction on Cu-based electrodes

We demonstrate that molecular coordination and photothermal excitation synergistically regulate CO2 electroreduction selectivity on Cu. Phenanthroline (Phen)–functionalized and laser-treated Cu electrodes were investigated under 0.1 M KHCO3 at various conditions. Phen–Cu exhibited a total hydrocarbon Faradaic efficiency (FE) of 19.2% and a chain-growth probability (α) of 0.333, surpassing bare Cu (9.17%, 0.224). Illumination at 520 nm triggered localized photothermal activation, quadrupling the C3+ hydrocarbon FE (0.076%). The optimum Phen concentration (0.25 μM) maximized multicarbon selectivity, while deviations in potential or ionic environment shifted selectivity toward C1 products. EIS analysis revealed the lowest charge-transfer resistance and highest capacitance for Phen–Cu520, indicating accelerated interfacial kinetics. XPS and valence-band spectra confirmed Cu0/Cu+ stabilization, persistent N−Cu coordination, and a VB onset shift associated with stronger electronic coupling. These results reveal that ligand-photothermal synergy creates a nonequilibrium, Cu0/Cu+-rich interface that promotes CO dimerization and chain growth, providing a new strategy for directing electrochemical Fischer–Tropsch-like chemistry.