| People | Locations | Statistics |
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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Macphee, Donald
University of Aberdeen
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (19/19 displayed)
- 2023Fairly and Rapidly Assessing Low Carbon Concrete Made with Slowly Reacting Cements
- 2020Exposed Aggregate Areas and Photocatalytic Efficiency of Photocatalytic Aggregate Mortarcitations
- 2019Photocatalytic Functionalized Aggregatecitations
- 2018The cuboid method for measurement of thermal properties of cement-based materials using the guarded heat flow metercitations
- 2017The reactivity of aluminosilicate glasses in cements - effects of Ca content on dissolution characteristics and surface precipitationcitations
- 2017An investigation of the electronic, structural and magnetic properties of the ruddlesden-popper phase Sr3RuCoO7citations
- 2016An investigation of the optical properties and water splitting potential of the coloured metallic perovskites Sr1-xBaxMoO3citations
- 2016Band structure and charge carrier dynamics in (W,N)-codoped TiO2 resolved by electrochemical impedance spectroscopy combined with UV-vis and EPR spectroscopiescitations
- 2016The Structure and Optical Properties of Sr1-xCaxMoO3citations
- 2015Properties and photochemistry of valence-induced-Ti3+ enriched (Nb,N)-codoped anatase TiO2 semiconductorscitations
- 2011A physico-chemical basis for novel cementitious binderscitations
- 2010Novel cement systems (sustainability)citations
- 2010Effect of Calcium Additions on N-A-S-H Cementitious Gelscitations
- 2010Effect on fresh C-S-H gels of the simultaneous addition of alkali and aluminiumcitations
- 2010Factors influencing colour in white Portland cements
- 2010Engineering Photocatalytic Cements: Understanding TiO2 Surface Chemistry to Control and Modulate Photocatalytic Performancescitations
- 2010Stability of synthetic calcium silicate hydrate gels in presence of alkalis, aluminum, and soluble silicacitations
- 2009Rhodamine B discolouration on TiO 2 in the cement environmentcitations
- 2009Study of the decalcification process in mortars degraded by NH4NO3 by using ultrasonic techniquescitations
Places of action
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article
Band structure and charge carrier dynamics in (W,N)-codoped TiO2 resolved by electrochemical impedance spectroscopy combined with UV-vis and EPR spectroscopies
Abstract
<p>Semiconductor photocatalysis is on the verge of (probably) its most important deployment and boost since the pioneering paper of Fujishima and Honda in 1972. Photo-generation of unbound excitons, i.e. separated conduction band electrons and valence band positive holes, is the fundamental primary process triggering charge separation in solid semiconductors necessary to initiate their photocatalytic activity. Immediately after being generated, charge carriers can undergo processes like recombination, trapping in mid-band-gap states or, paramount for photocatalytic processes, transfer to species adsorbed on the solid semiconductor surface. In TiO<sub>2</sub> and doped TiO<sub>2</sub>, interfacial charge transfers are the slowest amongst the primary processes; therefore, electron (and hole) transfer most likely occurs from single electron traps (i.e. involving radical species). We report here on an effective approach combining electrochemical impedance spectroscopy with other spectroscopic techniques such as UV-vis and electron paramagnetic resonance. This approach allows deriving important information about band structure and following electron dynamics triggered by photon absorption. The redox potentials of the band edges and the influence of the dopants on the band structure are elucidated by electrochemical impedance spectroscopy combined with UV-vis spectroscopy. Electron dynamics are then studied using electron paramagnetic resonance spectroscopy, to elucidate the photochemical reactions at the basis of the photo-generated electron-hole pairs, and subsequent trapping and/or recombination. Results of a TiO<sub>2</sub> sample containing W and N as dopants (0.1at.% of W) highlight a narrowing of the intrinsic band gap of about 0.12eV. The semiconductor visible light photochemistry is driven by diamagnetic donor states [N<sub>i</sub>O]<sup>-</sup>, and [N<sub>i</sub>O]w<sup>-</sup> (formally NO<sup>3-</sup>), from which electrons can be excited to the conduction band, generating EPR active paramagnetic [N<sub>i</sub>O]<sup> </sup> and [N<sub>i</sub>O]<sup> </sup> <sub>w</sub> states (formally NO<sup>2-</sup>). The formation of W<sup>5+</sup> electron trapping states, energetically more favourable than Ti<sup>3+</sup> electron trapping states, is also identified.</p>