Inhibited proton transfer enhances Au-catalyzed CO[subscript 2]-to-fuels selectivity
Name
Wuttig-2016-Inhibited proton tra.pdf
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Author(s)
Wuttig, Anna
Yaguchi, Momo
Motobayashi, Kenta
Osawa, Masatoshi
Surendranath, Yogesh
Alternative Title
Inhibited proton transfer enhances Au-catalyzed CO2-to-fuels selectivity
Date Issued
July 2016
Journal
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
Abstract
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.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1073/pnas.1602984113
