Selective CO 2 Electroreduction to CO by an Organometallic Nickel Catalyst Featuring a C 3 –Symmetric Tris(Phosphino)Alkyl Ligand

High Resolution Image Download MS PowerPoint Slide We report a Nickel CO 2 reduction electrocatalyst based on a C 3 -symmetric tris(phosphino)alkyl ligand, CNPPh 3, which displays a metalated axial carbon atom. Catalyst Ni H Br selectively reduces CO 2 to CO (FY CO = 94%) at −2.3 V vs Fc +/0 with a TO F max = 65 s –1 in DMF/[TBA]PF 6 with 3.5 M of added H 2 O. Cyclic voltammetry (CV) and an exhaustive computational study of the reaction mechanism show that our Ni II complex undergoes two one-electron reduction events before the CO 2 binding step. Afterward, the catalytic CO 2 reduction takes place through a reduction-first pathway. The formation of a Ni–CO intermediate along the CO 2 reduction pathway was inferred by CV, and the corresponding [Ni II –CO] + complex was isolated. FTIR spectroelectrochemistry (SEC) allowed for the detection of three different Ni–CO species: [Ni–CO] +, [Ni–CO] 0, and [Ni–CO] − . This work provides critical insights into the electrocatalytic CO 2 reduction, laying the foundation for efficient CO 2 conversion strategies.