Inhibited proton transfer enhances Au-catalyzed CO[subscript 2]-to-fuels selectivity
Author(s)
Wuttig, Anna; Yaguchi, Momo; Motobayashi, Kenta; Osawa, Masatoshi; Surendranath, Yogesh
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Alternative title
Inhibited proton transfer enhances Au-catalyzed CO2-to-fuels selectivity
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CO[subscript 2] reduction in aqueous electrolytes suffers efficiency losses because of the simultaneous reduction of water to H[subscript 2]. We combine in situ surface-enhanced IR absorption spectroscopy (SEIRAS) and electrochemical kinetic studies to probe the mechanistic basis for kinetic bifurcation between H[subscript 2] and CO production on polycrystalline Au electrodes. Under the conditions of CO[subscript 2] reduction catalysis, electrogenerated CO species are irreversibly bound to Au in a bridging mode at a surface coverage of ∼0.2 and act as kinetically inert spectators. Electrokinetic data are consistent with a mechanism of CO production involving rate-limiting, single-electron transfer to CO[subscript 2] with concomitant adsorption to surface active sites followed by rapid one-electron, two-proton transfer and CO liberation from the surface. In contrast, the data suggest an H[subscript 2] evolution mechanism involving rate-limiting, single-electron transfer coupled with proton transfer from bicarbonate, hydronium, and/or carbonic acid to form adsorbed H species followed by rapid one-electron, one-proton, or H recombination reactions. The disparate proton coupling requirements for CO and H[subscript 2] production establish a mechanistic basis for reaction selectivity in electrocatalytic fuel formation, and the high population of spectator CO species highlights the complex heterogeneity of electrode surfaces under conditions of fuel-forming electrocatalysis.
Date issued
2016-07Department
Massachusetts Institute of Technology. Department of ChemistryJournal
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences (U.S.)
Citation
Wuttig, Anna et al. “Inhibited Proton Transfer Enhances Au-Catalyzed CO 2 -to-Fuels Selectivity.” Proceedings of the National Academy of Sciences 113.32 (2016): E4585–E4593. © 2016 National Academy of Sciences
Version: Final published version
ISSN
0027-8424
1091-6490