Bifunctional electrocatalysis for CO₂ reduction via surface capping-dependent metal–oxide interactions

Multi-component materials are a new trend in catalyst development for electrochemical CO₂ reduction. Understanding and managing the chemical interactions within a complex catalyst structure may unlock new or improved reactivity, but is scientifically challenging. We report the first example of capping ligand-dependent metal–oxide interactions in Au/SnO₂ structures for electrocatalytic CO₂ reduction. Cetyltrimethylammonium bromide capping on the Au nanoparticles enables bifunctional CO₂ reduction where CO is produced at more positive potentials and HCOO⁻ at more negative potentials. With citrate capping or no capping, the Au–SnO₂ interactions steer the selectivity toward H₂ evolution at all potentials. Using electrochemical CO oxidation as a probe reaction, we further confirm that the metal–oxide interactions are strongly influenced by the capping ligand.