Toward Broad-Spectrum Overall Water Splitting: An Iodide-Mediated Z-Scheme Pairing Spectrally Complementary WO3 and Single-Walled Carbon Nanotube Photocatalysts
- 1Department of Materials Design and Engineering, Faculty of Sustainable Design, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
Abstract
Extending particulate overall water splitting beyond ultraviolet (UV) and short-wavelength visible light is important for more fully utilizing the solar spectrum. Here, we report a particulate Z-scheme system comprising a single-walled carbon nanotube (SWCNT)/fullerodendron nanohybrid (CNT photocatalyst) for H2 evolution, commercially available WO3 for O2 evolution, and an iodide-derived redox mediator. Under air mass (AM) 1.5G simulated sunlight (1000 W m−2) and without sacrificial reagents or external bias, the optimized system evolved H2 and O2 at 15.2 and 7.6 µmol h−1, respectively—a stoichiometric 2:1 ratio—corresponding to a solar-to-hydrogen conversion efficiency of 0.08%. Near-stoichiometric gas evolution was sustained over three 6 h cycles, with 91% of the initial activity retained in the third cycle; X-ray diffraction revealed no detectable bulk structural change in WO3. The two photocatalysts play complementary roles: WO3 oxidizes water under near-UV and short-wavelength visible light, whereas the CNT photocatalyst exhibits chirality-dependent absorption spanning the visible to near-infrared region and evolves H2 at selected wavelengths in sacrificial half-reactions. Coupling these functions through an iodide-based redox shuttle extends CNT photocatalysis beyond sacrificial H2 evolution and offers a materials-design strategy for extending the usable spectral range of particulate overall water splitting.
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BibTeX
@article{pham2026toward,
title = {{Toward Broad-Spectrum Overall Water Splitting: An Iodide-Mediated Z-Scheme Pairing Spectrally Complementary WO3 and Single-Walled Carbon Nanotube Photocatalysts}},
author = {Thi Linh Pham and Tetsuo Aida and Yutaka Takaguchi},
journal = {Catalysts},
year = {2026},
month = oct,
doi = {10.3390/catal16100933},
url = {https://www.mdpi.com/2073-4344/16/10/933},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Toward Broad-Spectrum Overall Water Splitting: An Iodide-Mediated Z-Scheme Pairing Spectrally Complementary WO3 and Single-Walled Carbon Nanotube Photocatalysts
AU - Thi Linh Pham
AU - Tetsuo Aida
AU - Yutaka Takaguchi
PY - 2026
DA - 2026/10/21
JO - Catalysts
DO - 10.3390/catal16100933
UR - https://www.mdpi.com/2073-4344/16/10/933
AB - Extending particulate overall water splitting beyond ultraviolet (UV) and short-wavelength visible light is important for more fully utilizing the solar spectrum. Here, we report a particulate Z-scheme system comprising a single-walled carbon nanotube (SWCNT)/fullerodendron nanohybrid (CNT photocatalyst) for H2 evolution, commercially available WO3 for O2 evolution, and an iodide-derived redox mediator. Under air mass (AM) 1.5G simulated sunlight (1000 W m−2) and without sacrificial reagents or external bias, the optimized system evolved H2 and O2 at 15.2 and 7.6 µmol h−1, respectively—a stoichiometric 2:1 ratio—corresponding to a solar-to-hydrogen conversion efficiency of 0.08%. Near-stoichiometric gas evolution was sustained over three 6 h cycles, with 91% of the initial activity retained in the third cycle; X-ray diffraction revealed no detectable bulk structural change in WO3. The two photocatalysts play complementary roles: WO3 oxidizes water under near-UV and short-wavelength visible light, whereas the CNT photocatalyst exhibits chirality-dependent absorption spanning the visible to near-infrared region and evolves H2 at selected wavelengths in sacrificial half-reactions. Coupling these functions through an iodide-based redox shuttle extends CNT photocatalysis beyond sacrificial H2 evolution and offers a materials-design strategy for extending the usable spectral range of particulate overall water splitting.
SN - 2073-4344
ER -