Oxygen Plasma Induced Hierarchically Structured Gold Electrocatalyst for Selective Reduction of Carbon Dioxide to Carbon Monoxide

Abstract

Electrochemical reduction of CO 2 into C1 products with high energy density has attracted attention due to the demands for renewable energy sources. Herein, we demonstrate a selective electrocatalytic CO 2 reduction system where the cathode consists of hierarchically structured Au islands catalysts. To be more specific, the Au islands were prepared by oxygen plasma treatment on the Au foil, to increase the current density for the selective production of carbon monoxide with over 95% of faradaic efficiency. Faradaic efficiency, production rate, and the onset potential for CO 2 reduction were significantly improved by the expanded surface area, compared with a polycrystalline Au electrode. Furthermore, the performance of CO 2 reduction to CO was enhanced by adding ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) which has high CO 2 -capture ability and catalytic activity. On the other hand, the rate-determining step of the Au electrode for the CO production determined by Tafel plots was found to be consistent with the initial one electron transfer step to form the surface adsorbed CO 2• -intermediates regardless of the application of hierarchically structured catalyst and ionic liquid in the CO 2 reduction system.

Recent Advances in Inorganic Heterogeneous Electrocatalysts for Reduction of Carbon Dioxide

“…Koh et al fabricated a hierarchically structured Au film composed of nanoscale islands by the oxygen‐plasma method . Thanks to the expanded specific surface area, the Au island‐type electrocatalyst showed an outstanding CO 2 reduction performance including enhanced current density, good selectivity for CO (FE > 95%) and relatively positive onset potential as compared with the Au foil.…”

Nanostructured nonprecious metal catalysts for electrochemical reduction of carbon dioxide

“…The improved catalytic performances are demonstrated in nanostructured catalysts. Typically, nanostructured noble metals such as Au, Ag, and Pd have exhibited highly selective conversion of CO 2 to CO at relatively low overpotentials [14][15][16][17][18][19][20][21][22][23][24][25][26]. For example, monodisperse 8-nm Au nanoparticles showed a faradaic efficiency (FE) of up to 90% at −0.67 V vs. the reversible hydrogen electrode (RHE) in an aqueous 0.5 M KHCO 3 electrolyte [16].…”

Contributors to Enhanced CO2 Electroreduction Activity and Stability in a Nanostructured Au Electrocatalyst

“…Moreover, Koh et al. reported that Au hierarchical nanostructures prepared using oxygen plasma treatment increase the current density for the selective production of CO . The origin of these behaviors has not yet been fully determined in these oxidation‐mediated nanostructured Au catalysts.…”