A scalable route to mixed and layered sandwich-structured carbonaceous–anatase TiO2 coatings with bi-functional photocatalytic activity for air pollution remediation and solar water splitting
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
This study showcases how carbonaceous materials, including graphene (G), fullerene (F), and multi-walled carbon nanotubes (MWCNTs), can be integrated within titanium dioxide (TiO2) films as either: (i) mixed or (ii) layered sandwich structures (TiO2/carbonaceous material/TiO2) and show bifunctional photocatalytic activity. Our composites are engineered to address both NOx pollution and water splitting within the same platform. In the mixed composite (TGmix), graphene's high conductivity and electron-accepting ability enhance the photo-oxidation of NOx, where under UVA light 17.6 % NO and 9.6 % total NOx removal was seen, which was significantly higher than TiO2 alone, which showed 6.8 % NO and 1.3 % total NOx removal. Whereas in the sandwich-layered composite (TGT), the architecture promotes hole accumulation on the surface, favouring water splitting, with incident-photon-to-current efficiency (IPCE) reaching 68 % at 1.23 VRHE (pH = 7) under 250 nm illumination; a factor of ∼2 increase compared to TiO2 alone. Transient photocurrent (TPC) and diffuse reflectance transient absorption spectroscopy (DR-TAS) were employed operando to probe the kinetics of electron extraction and hole-mediated water oxidation. At 1.23 VRHE, the TGT sample showed slightly faster electron extract kinetics to T (TGT: t50 %–0.25 ms and T: t50 %–0.268 ms), along with a significantly higher long-lived hole carrier population that drove water oxidation, which were found to linearly correlate with the observed photocurrent density.
Our wholistic study, including in operando investigations, informs the rational design of active carbonaceous composite coatings within anatase TiO2 that can be grown at scale for applications in NOx air pollution remediation and solar water splitting.
Our wholistic study, including in operando investigations, informs the rational design of active carbonaceous composite coatings within anatase TiO2 that can be grown at scale for applications in NOx air pollution remediation and solar water splitting.
Date Issued
2026-01-01
Date Acceptance
2025-10-13
Citation
Carbon, 2026, 246
ISSN
0008-6223
Publisher
Elsevier BV
Journal / Book Title
Carbon
Volume
246
Copyright Statement
© 2025 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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Publication Status
Published
Article Number
120939
Date Publish Online
2025-10-19