Modification of TiO2 with metal chalcogenide nanoclusters for hydrogen evolution

Using density functional theory, corrected for on-site Coulomb interactions (DFT + U), we have investigated surface modification of TiO2 with metal chalcogenide nanoclusters for hydrogen evolution. The nanoclusters have composition M4X4 (M = Sn, Zn; X = S, Se) and are adsorbed at the rutile (110) su...

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Bibliographic Details
Published in:JPhys Energy 2021-04, Vol.3 (2)
Main Authors: Rhatigan, Stephen, Niemitz, Lorenzo, Nolan, Michael
Format: Article
Language:English
Subjects:
Adsorption
Catalytic activity
Chalcogenides
Clusters
Density functional theory
Density of states
Electromagnetic absorption
Exothermic reactions
Free energy
Hydrogen
Hydrogen evolution reactions
Materials selection
Nanoclusters
Photocatalysis
Red shift
Rutile
Selenium
Surface chemistry
Titanium dioxide
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Summary:Using density functional theory, corrected for on-site Coulomb interactions (DFT + U), we have investigated surface modification of TiO2 with metal chalcogenide nanoclusters for hydrogen evolution. The nanoclusters have composition M4X4 (M = Sn, Zn; X = S, Se) and are adsorbed at the rutile (110) surface. The nanoclusters adsorb exothermically, with adsorption energies in the range −2.8 eV to −2.5 eV. Computed density of states (DOS) plots show that cluster-derived states extend into the band-gap of the rutile support, which indicates that modification produces a redshift in light absorption. After modification, photoexcited electrons and holes are separated onto surface and cluster sites, respectively. The free energy of H adsorption is used to assess the performance of metal chalcogenide modified TiO2 as a catalyst for the hydrogen evolution reaction (HER). Adsorption of H at nanocluster (S, Se) and surface (O) sites is considered, together with the effect of H coverage. Adsorption free energies at cluster sites in the range −0.15 eV to 0.15 eV are considered to be favourable for HER. The results of this analysis indicate that the sulphide modifiers are more active towards HER than the selenide modifiers and exhibit hydrogen adsorption free energies in the active range, for most coverages. Conversely, the adsorption free energies at the selenide nanoclusters are only in the active range at low H coverages. Our results indicate that surface modification with small, dispersed nanoclusters of appropriately selected materials can enhance the photocatalytic activity of TiO2 for HER applications.
ISSN:2515-7655
DOI:10.1088/2515-7655/abe424