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Univ. Paris-Saclay
The potential of Imogolite nanotubes as (co-)photocatalyst: a linear-scaling Density Functional Theory study
Gilberto Teobaldi
Department of Chemistry, University of Liverpool
Vendredi 12/02/2016, 11:00-12:00
NIMBE Bât.546, p.21, CEA-Saclay

We report a linear-scaling density functional theory (DFT) study of the structure, wall-polarization absolute band-alignment and optical absorption of several, recently synthesized, open-ended imogolite (Imo) nanotubes (NTs), namely single-walled (SW) aluminosilicate (AlSi), SW aluminogermanate (AlGe), SW methylated aluminosilicate (AlSi-Me), and double-walled (DW) AlGe NTs. Simulations with three different semi-local and dispersion-corrected DFTfunctionals reveal that the NT wall-polarization can be increased by nearly a factor of four going from SW-AlSi-Me to DW-AlGe. Absolute vacuum alignment of the NT electronic bands and comparison with those of rutile and anatase TiO2 suggest that the NTs may exhibit marked propensity to both photo-reduction and hole-scavenging. Characterization of the NTs’ bandseparation and optical properties reveal the occurrence of (near-)UV inside–outside charge-transfer excitations, which may be effective for electron–hole separation and enhanced photocatalytic activity. Finally, the effects of the NTs’ wall-polarization on the absolute alignment of electron and hole acceptor states of interacting water (H2O) molecules are quantified and discussed.

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