We report a linear-scaling, in-situ optimised basis-set, Density Functional Theory (DFT) investigation of single-walled open-ended aluminosilicate nanotubes with selective methyl functionalization (AlSiMe NTs) at the inner surface [1,2]. In line with experimental pore size distributions [1], optimization of the AlSiMe NT structure with six different semi-local and non-local DFT functionals suggests the presence of a shallow energetic-minimum spanning NTs with 28, 30 and 32 Al-atoms in their circumference, resulting in a larger diameter than pristine aluminosilicate nanotubes (AlSi NTs). Analysis of the AlSiMe NTs electronic structure reveals the wall polarization and real-space separation between valence and conduction bands, characteristic of pristine AlSi NTs [3], to be qualitatively unaffected by the methylation. The wall of the AlSiMe NTs are however found to be less polarized (-7/-25%) than AlSi NTs, with NTs of a smaller diameter being less polarized. Spurred by recent measurements suggesting a high selectivity for hydrophilic reagents on different sides of the tube cavity, we quantify the affect of the wall polarization on the absolute alignment of states for adsorbed H2O molecules inside and outside the tube. These simulations indicate shifts as large as 2 eV between inner-outer H2O states and combined with the reported hydrophobic nature of the AlSiMe NT cavity [1,2], these findings should be useful for informing the design of novel strategies to integrate chemical separation and heterogeneous (photo-)catalysis in confined volumes. [1] I. Bottero et al., Phys. Chem. Chem. Phys., 2011, 13, 744 [2] C. Zanzottera et al. J. Phys. Chem. C, 2012, 116, 20417 [3] G. Teobaldi et al., J. Phys.: Condens. Mat., 2009, 21, 195301

Selectively inner-surface methylated single-walled aluminosilicate nanotubes, toward integration of chemical separation and (photo-)catalysis in confined volumes?

249th National Meeting (2015)

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