Observation of transition from rate law to Butler–Volmer controlled water oxidation kinetics on hematite photoanodes
Author(s)
Type
Journal Article
Abstract
Despite its central role in photoelectrochemical (PEC) water splitting, the mechanistic pathway of water oxidation on metal oxides remains unresolved, with population-based and Butler–Volmer (BV) models offering distinct views on how surface valence band holes drive the reaction. Here, we bring together these two perspectives by combining operando photoinduced absorption (PIA) spectroscopy with photocurrent analyses on α-Fe2O3 (hematite) photoanodes as a function of light intensity. We find a crossover from population-controlled, rate law water oxidation at low hole densities to a BV-like, potential driven regime at high densities, triggered by band edge unpinning once surface M–OH species are fully oxidized, and excess holes accumulate without compensation. This mechanistic transition unifies competing models of interfacial charge transfer and reveals design principles for optimizing water oxidation in metal oxide photoelectrodes.
Date Issued
2026-02-11
Date Acceptance
2026-01-22
Citation
Journal of the American Chemical Society, 2026, 148 (5), pp.4833-4838
ISSN
0002-7863
Publisher
American Chemical Society (ACS)
Start Page
4833
End Page
4838
Journal / Book Title
Journal of the American Chemical Society
Volume
148
Issue
5
Copyright Statement
© 2026 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY 4.0 .
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/41607339
Publication Status
Published
Coverage Spatial
United States
Date Publish Online
2026-01-29