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Electrocatalytic Reduction Of Carbon Dioxide By The Binuclear Copper Complex [Cu2(6-(diphenylphosphino-2,2'-bipyridyl)2(MeCN)2][PF6]2
Published 1994 · Chemistry
The dicopper complex [Cuz(p-PPh~bipy)z(MeCN)z] [PF&, 1 (PPhzbipy = 6-(diphenylphosphino)-2,2'-bipyridyl), and its pyridine analog [Cu~(~1-PPh~bipy)~(py)~][PF6]2, 2, are electrocatalysts for the reduction of carbon dioxide. Two sequential single-electron transfers to 1 are observed at E1/2(2+/+) = -1.35 V vs SCE and at E1/2(+/0) = -1.53 V vs SCE in MeCN. Both are required to effect COz reduction. A 13C-labeling study shows that 13C02 is selectively reductively disproportionated to 13C0 and 13c032-. Cyclic and rotating disk voltammetry, chronoamperometry, and computer simulation of cyclic voltammetry have been applied to characterize the heterogeneous electron transfers and homogeneous chemical kinetics of catalysis by the dicopper complexes. Infrared spectroelectrochemical measurements were used to observe products formed during electrocatalysis. On the basis of these kinetic and spectroscopic studies, a mechanism for the catalytic reduction of COz is proposed.