Concavity promotes CO selectivity for electrochemical CO2 reduction on gold nanoparticles.

Gold is highly selective for the electrochemical reduction of CO2 to CO in aqueous media; however, performance is sensitive to surface structure and morphology. Here, size- and shape-matched pairs of concave and non-concave gold nanoparticles are compared. Concave cubic and concave stella octangula are shown to have greater intrinsic activity, higher CO faradaic efficiencies, and improved CO/H2 ratios compared to their non-concave counterparts. Importantly, the concave stella octangula maintains >85% CO selectivity -0.6 VRHE for 8 hours of electrochemical CO2 reduction.