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A combination of EPR, microscopy, electrophoresis and theory to elucidate the chemistry of W- and N-Doped TiO2 nanoparticle/water interfaces

Gorman, Sam, Rickaby, Kirstie, Lu, Li, Kiely, Christopher J., Macphee, Donald E. and Folli, Andrea 2021. A combination of EPR, microscopy, electrophoresis and theory to elucidate the chemistry of W- and N-Doped TiO2 nanoparticle/water interfaces. Catalysts 11 (11) , 1305. 10.3390/catal11111305

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Abstract

The doping of TiO2-based nanomaterials for semiconductor-sensitised photoreactions has been a practice extensively studied and applied for many years. The main goal remains the improvement of light harvesting capabilities under passive solar irradiation, that in the case of undoped TiO2 is limited and restricted to relatively low latitudes. The activity and selectivity of doped TiO2 photocatalysts are generally discussed on the basis of the modified band structure; energetics of intrinsic or extrinsic band gaps including trapping states; redox potentials of band edges, including band bending at solid/fluid interfaces; and charge carriers scavenging/transfer by/to adsorbed species. Electron (and hole) transfer to adsorbates is often invoked to justify the formation of highly reactive species (e.g., HO. from water); however, a complete description of the nanoparticle surface chemistry dictating adsorption/desorption events is often missing or overlooked. Here, we show that by employing a surface electrochemical triple-layer (TLM) approach for the nanoparticles/water interface, in combination with electron paramagnetic resonance spectroscopy (EPR), transmission electron microscopy and electrophoretic measurements, we can elucidate the surface chemistry of doped TiO2 nanoparticles and link it to the nature of the dopants. Exemplifying it for the cases of undoped, as well as W- and N-doped and codoped TiO2 nanoparticles, we show how surface charge density; surface, Stern and ζ potentials; surface acidity constants; and speciation of surface sites are influenced by the nature of the dopants and their loading.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Additional Information: This is an open access article distributed under the Creative Commons Attribution License
Publisher: MDPI
ISSN: 2073-4344
Funders: European Commission (FP7-ENV-2011-ECO-INNO-TwoStage 283062)
Date of First Compliant Deposit: 8 November 2021
Date of Acceptance: 18 October 2021
Last Modified: 15 Nov 2021 10:15
URI: https://orca.cardiff.ac.uk/id/eprint/145366

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