Isotopic Probe Illuminates the Role of the Electrode Surface in Proton Coupled Hydride Transfer Electrochemical Reduction of Pyridinium on Pt(111)
Year: 2015
Type: article
Abstract: A recently proposed mechanism for electrochemical CO 2 reduction on Pt (111) catalyzed by aqueous acidic pyridine solutions suggests that the observed redox potential of ca. −600 mV vs. SCE is due to the one-electron reduction of pyridinium through proton coupled electron transfer (PCET) to form H atoms adsorbed on the Pt surface (H ads ). The initial pyridinium reduction was probed isotopically via deuterium substitution. A combined experimental and theoretical analysis found equilibrium isotope effects (EIE) due to deuterium substitution at the acidic pyridinium site. A shift in the cathodic cyclic voltammetric half wave potential of −25 mV was observed, consistent with the theoretical prediction of −40 mV based on the recently proposed reaction mechanism where pyridinium is essential to establish a high concentration of Brønsted acid in contact with the substrate CO 2 and with the Pt surface. A prefeature in the cyclic voltammogram was examined under isotopic substitution and indicated an H ads intermediate in pyridinium reduction. Theoretical prediction and observation of an EIE supported the assignment of the cathodic wave to the proposed reduction of pyridinium through PCET forming H ads and eventually H 2 on the Pt surface.
DOI: 10.1149/2.0821514jes
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $1,950
Funders: National Science Foundation, U.S. Department of Energy, Yale University, Oak Ridge Associated Universities, National Energy Research Scientific Computing Center, Office of Science, Oak Ridge Institute for Science and Education, Multidisciplinary University Research Initiative, Division of Chemistry, Basic Energy Sciences, Air Force Office of Scientific Research, Brookhaven National Laboratory
Awards: G103063029, G1126863173, G1286251239, G132563423, G1336448005, G1523888516, G1572106353, G1852020741, G2988778103, G3309502301, G338944111, G365113682, G4388105696, G4683634513, G491774827, G498139845, G5292656900, G549834383, SusChEM: A Mechanistic Approach to Understanding and Lowering the Overpotential for CO2 Reduction to C1 Organic Products, G8013083466, G803281476, NEW; PHOTOELECTROCHEMICAL CONVERSION OF CARBON DIOXIDE TO METHANOL AND HIGHER ORDER ALCOHOLS; PI: ANDREW BOCARSLY, G8507651203, G857543222, G868353320, G969889393
OpenAlex ID: W2268338702