Issue 44, 2021

The electron-transfer intermediates of the oxygen evolution reaction (OER) as polarons by in situ spectroscopy

Abstract

The conversion of diffusive forms of energy (electrical and light) into short, compact chemical bonds by catalytic reactions regularly involves moving a carrier from an environment that favors delocalization to one that favors localization. While delocalization lowers the energy of the carrier through its kinetic energy, localization creates a polarization around the carrier that traps it in a potential energy minimum. The trapped carrier and its local distortion—termed a polaron in solids—can play a role as a highly reactive intermediate within energy-storing catalytic reactions but is rarely discussed as such. Here, we present this perspective of the polaron as a catalytic intermediate through recent in situ and time-resolved spectroscopic investigations of photo-triggered electrochemical reactions at material surfaces. The focus is on hole-trapping at metal–oxygen bonds, denoted M–OH*, in the context of the oxygen evolution reaction (OER) from water. The potential energy surface for the hole-polaron defines the structural distortions from the periodic lattice and the resulting “active” site of catalysis. This perspective will highlight how current and future time-resolved, multi-modal probes can use spectroscopic signatures of M–OH* polarons to obtain kinetic and structural information on the individual reaction steps of OER. A particular motivation is to provide the background needed for eventually relating this information to relevant catalytic descriptors by free energies. Finally, the formation of the O–O chemical bond from the consumption of M–OH*, required to release O2 and store energy in H2, will be discussed as the next target for experimental investigations.

Graphical abstract: The electron-transfer intermediates of the oxygen evolution reaction (OER) as polarons by in situ spectroscopy

Article information

Article type
Perspective
Submitted
22 Apr 2021
Accepted
06 Aug 2021
First published
19 Aug 2021

Phys. Chem. Chem. Phys., 2021,23, 24984-25002

The electron-transfer intermediates of the oxygen evolution reaction (OER) as polarons by in situ spectroscopy

H. Lyle, S. Singh, M. Paolino, I. Vinogradov and T. Cuk, Phys. Chem. Chem. Phys., 2021, 23, 24984 DOI: 10.1039/D1CP01760H

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