Abstract
Relatively few solution electrocatalysts for CO2 reduction in aqueous solutions are reported. However, to be sustainable, electrocatalytic CO2 reduction is likely to be coupled to water oxidation in a complete device. Here we report a water-soluble Mn polypyridyl complex for the electrocatalytic reduction of CO2 to CO. This complex shows activity across a broad pH range and an excellent selectivity at pH 9 (3.8:1, CO/H2). Cyclic voltammetry indicates activity across a range of different electrode materials (boron-doped diamond, glassy carbon, and Hg/Au amalgams).
Highlights
Rising atmospheric CO2 levels are a critical challenge facing society
Many homogeneous molecular catalysts which are selective for CO2 reduction are known[4] catalysis is often reported in organic solvents such as acetonitrile (CH3CN) or N,N-dimethylformamide (DMF) with an additional proton source added in a low concentration
The observation of CO2 reduction at −1.2 V corresponds to a very low overpotential, only 0.35 V, similar to that previously reported for a pyrenemodified Mn carbonyl complex in water[28] and among the lowest values reported for a water-soluble CO2 reduction electrocatalyst
Summary
Rising atmospheric CO2 levels are a critical challenge facing society. An attractive option is to electrocatalytically[1] or photocatalytically[2] reduce CO2 to fuels or feedstocks. A pyrene-modified [Mn(bpy)(CO)3Br] derivative was immobilized on MWCNT and was reported to operate in water at η = 0.55 and TONCO > 1000, with a mixture of H2, CO, and formate being produced depending on the catalyst surface loading.[28] Very recently, a polymerized Mn complex showed catalytic activity in water.[29] It is important that this class of catalysts is further studied in aqueous electrolytes; to the best of our knowledge, the homogeneous electrocatalytic reduction of CO2 in aqueous solvents has not been previously reported. (CO)3Br] shows a high level of selectivity toward CO2 reduction
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