Tuning catalyst-support interactions enable steering of electrochemical CO₂ reduction pathways

Tuning of catalyst-support interactions potentially offers a powerful means to control activity. However, rational design of the catalyst support is challenged by a lack of clear property-activity relationships. Here, we uncover how the electronegativity of a support influences reaction pathways in electrochemical CO₂ reduction. This was achieved by creating a model system consisting of Cu nanoparticles hosted on a series of carbon supports, each with a different heteroatom dopant of varying electronegativity. Notably, we discovered that dopants with high electronegativity reduce the electron density on Cu and induce a selectivity shift toward multicarbon (C₂₊) products. With this design principle, we built a composite Cu and F-doped carbon catalyst that achieves a C₂₊ Faradaic efficiency of 82.5% at 400 mA cm^-2, with stable performance for 44 hours. Using simulated flue gas, the catalyst attains a C₂₊ FE of 27.3%, which is a factor of 5.3 times higher than a reference Cu catalyst.