Electrochemical Performance Screening of Cu‐Based Multimetal Electrocatalysts for CO ₂ Reduction

Targeting the electrocatalytic CO ₂ reduction reaction (eCO ₂ RR) using complex multimetal catalysts is a relatively new approach in electrocatalyst design. We explored the eCO ₂ RR performance for lanthanoids and similar rare‐earth elements such as Gd, Sc, Tb, Nd, Sm, and Y as components in CuAgAl catalyst mixtures. Product selectivity is highly sensitive to the complexity of the catalysts (i.e. the number and identity of constituting elements) and the potential (activity) controlled by the compositions. Particularly, most of the Gd‐containing catalysts showed high Faradaic efficiency (FE) for C ₂₊ products (FE _C2+ ), >60%, at a current density of −400 mA cm ⁻² . Using mean absolute error analysis, we investigated the correlation between multimetal composition, product selectivity, and required potential at a defined current density. The modulation in product distribution is likely promoted by the distinct properties of the multimetal catalysts. Operando Raman measurements of two multimetal catalysts (Cu ₈₀ Ag ₅ Al ₅ Gd ₅ Sm ₅ and Cu ₈₀ Ag ₅ Al ₅ Nd ₅ Sm ₅ ) revealed different mechanisms shown by the variations in the local alkalinity of the microenvironments and catalyst reconstruction, despite both catalysts exhibit an FE _C2+ of 65%. Exploring multimetal catalysts expands the design space for elemental selection, allowing for distinct mechanisms that expand the understanding of selectivity modulation.