articleJournal of the American Chemical SocietySep 14, 2016GREEN OA

Hydrolysis of Electrolyte Cations Enhances the Electrochemical Reduction of CO 2 over Ag and Cu

University of Illinois Chicago · Lawrence Berkeley National Laboratory · +2 more institutions

PubMed
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Abstract

Electrolyte cation size is known to influence the electrochemical reduction of CO2 over metals; however, a satisfactory explanation for this phenomenon has not been developed. We report here that these effects can be attributed to a previously unrecognized consequence of cation hydrolysis occurring in the vicinity of the cathode. With increasing cation size, the pKa for cation hydrolysis decreases and is sufficiently low for hydrated K+, Rb+, and Cs+ to serve as buffering agents. Buffering lowers the pH near the cathode, leading to an increase in the local concentration of dissolved CO2. The consequences of these changes are an increase in cathode activity, a decrease in Faradaic efficiencies for H2 and CH4,…

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