Enhancing Activity and Reducing Cost for Electrochemical Reduction of CO ₂ by Supporting Palladium on Metal Carbides

Electrochemical CO ₂ reduction reaction (CO ₂ RR) with renewable electricity is a potentially sustainable method to reduce CO ₂ emissions. Palladium supported on cost-effective transition-metal carbides (TMCs) are studied to reduce the Pd usage and tune the activity and selectivity of the CO ₂ RR to produce synthesis gas, using a combined approach of studying thin films and practical powder catalysts, in situ characterization, and density functional theory (DFT) calculations. Notably, Pd/TaC exhibits higher CO ₂ RR activity, stability and CO Faradaic efficiency than those of commercial Pd/C while significantly reducing the Pd loading. In situ measurements confirm the transformation of Pd into hydride (PdH) under the CO ₂ RR environment. DFT calculations reveal that the TMC substrates modify the binding energies of key intermediates on supported PdH. This work suggests the prospect of using TMCs as low-cost and stable substrates to support and modify Pd for enhanced CO ₂ RR activity.