Structure Sensitivity in the Electrocatalytic Reduction of CO2 with Gold Catalysts

A golden opportunity: Gold is an active and selective electrocatalyst for the reduction of CO₂ to CO in aqueous electrolytes. An investigation of the structure sensitivity of Au single crystals for electrocatalytic CO₂ reduction establishes that reaction kinetics are strongly dependent on the surface structure. Under‐coordinated sites are revealed as the active sites for CO₂ reduction by selective poisoning experiments.

Abstract

An understanding of the influence of structural surface features on electrocatalytic reactions is vital for the development of efficient nanostructured catalysts. Gold is the most active and selective known electrocatalyst for the reduction of CO₂ to CO in aqueous electrolytes. Numerous strategies have been proposed to improve its intrinsic activity. Nonetheless, the atomistic knowledge of the nature of the active sites remains elusive. We systematically investigated the structure sensitivity of Au single crystals for electrocatalytic CO₂ reduction. Reaction kinetics for the formation of CO are strongly dependent on the surface structure. Under‐coordinated sites, such as those present in Au(110) and at the steps of Au(211), show at least 20‐fold higher activity than more coordinated configurations (for example, Au(100)). By selectively poisoning under‐coordinated sites with Pb, we have confirmed that these are the active sites for CO₂ reduction.

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