Chelating N-Heterocyclic Carbene Ligands Enable Tuning of Electrocatalytic CO Reduction to Formate and Carbon Monoxide: Surface Organometallic Chemistry.

Reported here is the chelate effect as a design principle for tuning heterogeneous catalysts for electrochemical CO reduction. Palladium functionalized with a chelating tris-N-heterocyclic carbene (NHC) ligand (Pd-timtmb ) exhibits a 32-fold increase in activity for electrochemical reduction of CO to C1 products with high Faradaic efficiency (FE =86 %) compared to the parent unfunctionalized Pd foil (FE=23 %), and with sustained activity relative to a monodentate NHC-ligated Pd electrode (Pd-mimtmb ). The results highlight the contributions of the chelate effect for tailoring and maintaining reactivity at molecular-materials interfaces enabled by surface organometallic chemistry.