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Moss B, Svane KL, Nieto-Castro D, Rao RR, Scott SB, Tseng C, Sachs M, Pennathur A, Liang C, Oldham LI, Mazzolini E, Jurado L, Sankar G, Parry S, Celorrio V, Dawlaty JM, Rossmeisl J, Galán-Mascarós JR, Stephens IEL, Durrant JR. Cooperative Effects Drive Water Oxidation Catalysis in Cobalt Electrocatalysts through the Destabilization of Intermediates. J Am Chem Soc 2024; 146:8915-8927. [PMID: 38517290 PMCID: PMC10995992 DOI: 10.1021/jacs.3c11651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 03/07/2024] [Accepted: 03/08/2024] [Indexed: 03/23/2024]
Abstract
A barrier to understanding the factors driving catalysis in the oxygen evolution reaction (OER) is understanding multiple overlapping redox transitions in the OER catalysts. The complexity of these transitions obscure the relationship between the coverage of adsorbates and OER kinetics, leading to an experimental challenge in measuring activity descriptors, such as binding energies, as well as adsorbate interactions, which may destabilize intermediates and modulate their binding energies. Herein, we utilize a newly designed optical spectroelectrochemistry system to measure these phenomena in order to contrast the behavior of two electrocatalysts, cobalt oxyhydroxide (CoOOH) and cobalt-iron hexacyanoferrate (cobalt-iron Prussian blue, CoFe-PB). Three distinct optical spectra are observed in each catalyst, corresponding to three separate redox transitions, the last of which we show to be active for the OER using time-resolved spectroscopy and electrochemical mass spectroscopy. By combining predictions from density functional theory with parameters obtained from electroadsorption isotherms, we demonstrate that a destabilization of catalytic intermediates occurs with increasing coverage. In CoOOH, a strong (∼0.34 eV/monolayer) destabilization of a strongly bound catalytic intermediate is observed, leading to a potential offset between the accumulation of the intermediate and measurable O2 evolution. We contrast these data to CoFe-PB, where catalytic intermediate generation and O2 evolution onset coincide due to weaker binding and destabilization (∼0.19 eV/monolayer). By considering a correlation between activation energy and binding strength, we suggest that such adsorbate driven destabilization may account for a significant fraction of the observed OER catalytic activity in both materials. Finally, we disentangle the effects of adsorbate interactions on state coverages and kinetics to show how adsorbate interactions determine the observed Tafel slopes. Crucially, the case of CoFe-PB shows that, even where interactions are weaker, adsorption remains non-Nernstian, which strongly influences the observed Tafel slope.
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Affiliation(s)
- Benjamin Moss
- Imperial
College London, Molecular Sciences
Research Hub (MSRH), 82
Wood Lane, London W120BZ, United Kingdom
| | | | - David Nieto-Castro
- Institut
Català d’Investigació Química (ICIQ), Avda. Països Catalans 16, 43007, Tarragona, Spain
| | - Reshma R. Rao
- Imperial
College London, Molecular Sciences
Research Hub (MSRH), 82
Wood Lane, London W120BZ, United Kingdom
| | - Soren B. Scott
- Imperial
College London, Molecular Sciences
Research Hub (MSRH), 82
Wood Lane, London W120BZ, United Kingdom
| | - Cindy Tseng
- Imperial
College London, Molecular Sciences
Research Hub (MSRH), 82
Wood Lane, London W120BZ, United Kingdom
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089-1062, United
States
| | - Michael Sachs
- SLAC
National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Anuj Pennathur
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089-1062, United
States
| | - Caiwu Liang
- Imperial
College London, Molecular Sciences
Research Hub (MSRH), 82
Wood Lane, London W120BZ, United Kingdom
| | - Louise I. Oldham
- Imperial
College London, Molecular Sciences
Research Hub (MSRH), 82
Wood Lane, London W120BZ, United Kingdom
| | - Eva Mazzolini
- Imperial
College London, Molecular Sciences
Research Hub (MSRH), 82
Wood Lane, London W120BZ, United Kingdom
| | - Lole Jurado
- Institut
Català d’Investigació Química (ICIQ), Avda. Països Catalans 16, 43007, Tarragona, Spain
| | - Gopinathan Sankar
- SLAC
National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Stephen Parry
- Diamond
Light Source, Harwell
Science and Innovation Campus, Fermi Ave., Didcot OX11 0D, United Kingdom
| | - Veronica Celorrio
- Diamond
Light Source, Harwell
Science and Innovation Campus, Fermi Ave., Didcot OX11 0D, United Kingdom
| | - Jahan M. Dawlaty
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089-1062, United
States
| | - Jan Rossmeisl
- University
of Copenhagen, Universitetsparken
5, 2100 København
Ø, Denmark
| | - J. R. Galán-Mascarós
- Institut
Català d’Investigació Química (ICIQ), Avda. Països Catalans 16, 43007, Tarragona, Spain
- ICREA, Passeig Lluís Companys 23, 08010, Barcelona, Spain
| | - Ifan E. L. Stephens
- Imperial
College London, Molecular Sciences
Research Hub (MSRH), 82
Wood Lane, London W120BZ, United Kingdom
| | - James R. Durrant
- Imperial
College London, Molecular Sciences
Research Hub (MSRH), 82
Wood Lane, London W120BZ, United Kingdom
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Lewis NB, Bisbey RP, Westendorff KS, Soudackov AV, Surendranath Y. A molecular-level mechanistic framework for interfacial proton-coupled electron transfer kinetics. Nat Chem 2024; 16:343-352. [PMID: 38228851 DOI: 10.1038/s41557-023-01400-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 11/15/2023] [Indexed: 01/18/2024]
Abstract
Electrochemical proton-coupled electron transfer (PCET) reactions can proceed via an outer-sphere electron transfer to solution (OS-PCET) or through an inner-sphere mechanism by interfacial polarization of surface-bound active sites (I-PCET). Although OS-PCET has been extensively studied with molecular insight, the inherent heterogeneity of surfaces impedes molecular-level understanding of I-PCET. Herein we employ graphite-conjugated carboxylic acids (GC-COOH) as molecularly well-defined hosts of I-PCET to isolate the intrinsic kinetics of I-PCET. We measure I-PCET rates across the entire pH range, uncovering a V-shaped pH-dependence that lacks the pH-independent regions characteristic of OS-PCET. Accordingly, we develop a mechanistic model for I-PCET that invokes concerted PCET involving hydronium/water or water/hydroxide donor/acceptor pairs, capturing the entire dataset with only four adjustable parameters. We find that I-PCET is fourfold faster with hydronium/water than water/hydroxide, while both reactions display similarly high charge transfer coefficients, indicating late proton transfer transition states. These studies highlight the key mechanistic distinctions between I-PCET and OS-PCET, providing a framework for understanding and modelling more complex multistep I-PCET reactions critical to energy conversion and catalysis.
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Affiliation(s)
- Noah B Lewis
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ryan P Bisbey
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Karl S Westendorff
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Yogesh Surendranath
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
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Mayer JM. Bonds over Electrons: Proton Coupled Electron Transfer at Solid-Solution Interfaces. J Am Chem Soc 2023; 145:7050-7064. [PMID: 36943755 PMCID: PMC10080693 DOI: 10.1021/jacs.2c10212] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
This Perspective argues that most redox reactions of materials at an interface with a protic solution involve net proton-coupled electron transfer (PCET) (or other cation-coupled ET). This view contrasts with the traditional electron-transfer-focused view of redox reactions at semiconductors, but redox processes at metal surfaces are often described as PCET. Taking a thermodynamic perspective, transfer of an electron is typically accompanied by a stoichiometric proton, much as the chemistry of lithium-ion batteries involves coupled transfers of e- and Li+. The PCET viewpoint implicates the surface-H bond dissociation free energy (BDFE) as the preeminent energetic parameter and its conceptual equivalents, the electrochemical ne-/nH+ potential versus the reversible hydrogen electrode (RHE) and the free energy of hydrogenation, ΔG°H. These parameters capture the thermochemistry of PCET at interfaces better than electronic parameters such as Fermi energies, electron chemical potentials, flat-band potentials, or band-edge energies. A unified picture of PCET at metal and semiconductor surfaces is presented. Exceptions, limitations, implications, and future directions motivated by this approach are described.
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Affiliation(s)
- James M Mayer
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
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