Electrocatalytic and Solar‐Driven CO(2) Reduction to CO with a Molecular Manganese Catalyst Immobilized on Mesoporous TiO(2)

Electrocatalytic CO(2) reduction to CO was achieved with a novel Mn complex, fac‐[MnBr(4,4′‐bis(phosphonic acid)‐2,2′‐bipyridine)(CO)(3)] (MnP), immobilized on a mesoporous TiO(2) electrode. A benchmark turnover number of 112±17 was attained with these TiO(2)|MnP electrodes after 2 h electrolysis. Post‐catalysis IR spectroscopy demonstrated that the molecular structure of the MnP catalyst was retained. UV/vis spectroscopy confirmed that an active Mn–Mn dimer was formed during catalysis on the TiO(2) electrode, showing the dynamic formation of a catalytically active dimer on an electrode surface. Finally, we combined the light‐protected TiO(2)|MnP cathode with a CdS‐sensitized photoanode to enable solar‐light‐driven CO(2) reduction with the light‐sensitive MnP catalyst.