Multi-twinned gold nanoparticles with tensile surface steps for efficient electrocatalytic CO 2 reduction

CO 2 reduction reactions (CO 2 RR) powered by renewable electricity can directly convert CO 2 to hydrocarbons and fix the intermittent sustainable energy in portable chemical fuels. It is of great importance to develop advanced catalysts that can boost CO 2 RR with high activity, selectivity, and efficiency at low overpotentials. Here, we report the solution synthesis using H 2 O 2 to modify the surface structures of gold multi-twinned nanoparticles (AuMPs) and create tensile surface steps. Calculations predicted significantly enhanced CO 2 adsorption and boosted CO 2 RR capabilities with inhibited hydrogen evolution reaction activity for the tensile surface steps with modified electronic structure. The H 2 O 2 -treated AuMPs with surface steps and 3.83% tensile lattices showed much higher activity and selectivity at lower overpotentials for CO 2 RR than pristine gold nanoparticles. The CO-production current density reached about 98 mA cm −2 with a Faradaic efficiency of 95.7% at −0.30 V versus reversible hydrogen electrode in the flow cell, showing a half-cell energy efficiency as high as ∼83%. Our strategy represents a rational catalyst design by engineering the surface structures of metal nanoparticles and may find more applicability in future electrocatalysis.