Multi-twinned gold nanoparticles with tensile surface steps for efficient electrocatalytic CO₂ reduction

CO₂ reduction reactions (CO₂RR) powered by renewable electricity can directly convert CO₂ to hydrocarbons and fix the intermittent sustainable energy in portable chemical fuels. It is of great importance to develop advanced catalysts that can boost CO₂RR with high activity, selectivity, and efficiency at low overpotentials. Here, we report the solution synthesis using H₂O₂ to modify the surface structures of gold multi-twinned nanoparticles (AuMPs) and create tensile surface steps. Calculations predicted significantly enhanced CO₂ adsorption and boosted CO₂RR capabilities with inhibited hydrogen evolution reaction activity for the tensile surface steps with modified electronic structure. The H₂O₂-treated AuMPs with surface steps and 3.83% tensile lattices showed much higher activity and selectivity at lower overpotentials for CO₂RR 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. [Figure not available: see fulltext.].