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

Electrochemical CO reduction reaction (CO RR) with renewable electricity is a potentially sustainable method to reduce CO 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 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 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 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 RR activity.