Interplanar synergy of a copper-based electrocatalyst favors the reduction of CO2 into C2+ products†

Although electrocatalytic reduction of carbon dioxide (CO₂) into chemicals and fuels over Cu-based catalysts has been extensively investigated, the influence of their exposed facets on product selectivity remains elusive. To address this, a series of Cu-based catalysts with different ratios of exposed Cu(100) and Cu(111) facets were synthesized and examined for CO₂ electroreduction, based on which a remarkable interplanar synergistic effect on the selectivity of C₂₊ products was demonstrated. The optimized Cu-based interplanar synergistic catalyst could deliver a faradaic efficiency of 78% with a C₂₊ partial current density of 663 mA cm⁻², which is extremely superior to that of its corresponding Cu counterparts with only the Cu(111) or Cu(100) facet. The interplanar synergistic effect was disclosed using density functional theory calculations to mainly benefit from favorable adsorption and activation of CO₂ into *CO on the Cu(111) facet and significantly promoted C–C coupling on the interface of the Cu(111) and Cu(100) facets, as confirmed by observation of the favorable surface coverage of atop-bound and bridge-bound *CO as well as formation of *OC–CHO intermediates during in situ infrared spectroscopy analysis.