Spiral-Growth-Induced Nanosteps on Layered Oxyhalide Photocatalysts Enhance Anisotropic Charge Separation for Visible-Light Water Splitting
7 affiliations
- 1Department of Chemical Science and Engineering
- 2Kyoto University
- 3Department of Chemistry
- 4University of California, Davis
- 5Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama, Japan, 332-0012
- 6Research Institute for Interdisciplinary Science
- 7Okayama University
Abstract
Layered mixed-anion compounds are promising photocatalysts for solar fuel production owing to their visible-light absorption and suitable band-edge positions. However, their two-dimensional crystal structures hinder the spatial separation of reduction and oxidation sites because both photogenerated electrons and holes predominantly migrate in-plane along the layered frameworks. In particular, in plate-like particles reflecting this layered structure, charge carriers must travel relatively long lateral distances. Here, we overcome this limitation for the first time by introducing step structures on the basal planes, which shorten the lateral carrier migration while spatially separating redox sites. Using the layered oxyhalide Bi 4 NbO 8 Cl as a model photocatalyst, nanoscale steps are formed on the basal planes of plate-like crystals via screw-dislocation-driven spiral growth during flux synthesis. Subsequent acid etching converts the basal planes from photogenerated electron-rich to hole-accumulating surfaces, as revealed by surface photovoltage spectroscopy, enabling preferential photodeposition of reduction cocatalysts onto the electron-rich nanosteps. This asymmetric cocatalyst loading promotes anisotropic charge separation, resulting in a 16-fold enhancement in the photocatalytic H 2 evolution rate compared to the untreated sample and achieving one of the highest apparent quantum efficiencies reported for layered oxyhalide photocatalysts. Furthermore, etched samples with nanosteps exhibit enhanced photocatalytic water oxidation under visible-light Z-scheme water splitting, demonstrating the effectiveness of this surface engineering for solar water splitting. This study establishes spiral-growth-induced step formation combined with surface etching as a new design strategy for controlling carrier flow in layered photocatalysts, unlocking their potential for solar energy conversion.
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BibTeX
@misc{ogawa2026spiralgrowthinduced,
title = {{Spiral-Growth-Induced Nanosteps on Layered Oxyhalide Photocatalysts Enhance Anisotropic Charge Separation for Visible-Light Water Splitting}},
author = {Makoto Ogawa and Hajime Suzuki and Yi-Hao Chew and Mahya Salmanion and Rajesh Kandel and Osamu Tomita and Akinobu Nakada and Akira Yamakata and Frank E. Osterloh and Ryu Abe},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008362/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008362/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Spiral-Growth-Induced Nanosteps on Layered Oxyhalide Photocatalysts Enhance Anisotropic Charge Separation for Visible-Light Water Splitting
AU - Makoto Ogawa
AU - Hajime Suzuki
AU - Yi-Hao Chew
AU - Mahya Salmanion
AU - Rajesh Kandel
AU - Osamu Tomita
AU - Akinobu Nakada
AU - Akira Yamakata
AU - Frank E. Osterloh
AU - Ryu Abe
PY - 2026
DA - 2026/09/06
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008362/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008362/v1
AB - Layered mixed-anion compounds are promising photocatalysts for solar fuel production owing to their visible-light absorption and suitable band-edge positions. However, their two-dimensional crystal structures hinder the spatial separation of reduction and oxidation sites because both photogenerated electrons and holes predominantly migrate in-plane along the layered frameworks. In particular, in plate-like particles reflecting this layered structure, charge carriers must travel relatively long lateral distances. Here, we overcome this limitation for the first time by introducing step structures on the basal planes, which shorten the lateral carrier migration while spatially separating redox sites. Using the layered oxyhalide Bi 4 NbO 8 Cl as a model photocatalyst, nanoscale steps are formed on the basal planes of plate-like crystals via screw-dislocation-driven spiral growth during flux synthesis. Subsequent acid etching converts the basal planes from photogenerated electron-rich to hole-accumulating surfaces, as revealed by surface photovoltage spectroscopy, enabling preferential photodeposition of reduction cocatalysts onto the electron-rich nanosteps. This asymmetric cocatalyst loading promotes anisotropic charge separation, resulting in a 16-fold enhancement in the photocatalytic H 2 evolution rate compared to the untreated sample and achieving one of the highest apparent quantum efficiencies reported for layered oxyhalide photocatalysts. Furthermore, etched samples with nanosteps exhibit enhanced photocatalytic water oxidation under visible-light Z-scheme water splitting, demonstrating the effectiveness of this surface engineering for solar water splitting. This study establishes spiral-growth-induced step formation combined with surface etching as a new design strategy for controlling carrier flow in layered photocatalysts, unlocking their potential for solar energy conversion.
ER -