Chemically Selective Alternatives to Photoferroelectrics for Polarization‐Enhanced Photocatalysis: The Untapped Potential of Hybrid Inorganic Nanotubes

Abstract

Linear‐scaling density functional theory simulation of methylated imogolite nanotubes (NTs) elucidates the interplay between wall‐polarization, bands separation, charge‐transfer excitation, and tunable electrostatics inside and outside the NT‐cavity. The results suggest that integration of polarization‐enhanced selective photocatalysis and chemical separation into one overall dipole‐free material should be possible. Strategies are proposed to increase the NT polarization for maximally enhanced electron–hole separation.

Structural resolution of inorganic nanotubes with complex stoichiometry

“…In addition, the E /2 N profiles for ZZ and AC SiCH 3 in Fig. 7 , and earlier DFT results for ZZ SiCH 3 52 , also presents minima. Altogether these results indicate that, at least for Si-based INTs, the presence of an inner H-bonding network is not actually necessary for the appearance of a well-defined E /2 N minimum.…”

“…In the methylated INTs (m-INTs) discovered a few years ago 21 , inner hydroxyl groups are substituted by methyl groups, leading to a nominal composition (OH) 3 Al 2 O 3 Si(Ge)CH 3 . They are considered as ZZ nanotubes 21 , 22 , 30 , 34 , 52 , like their hydroxylated analogs. Narrow diameter distributions are reported 22 .…”

“…For the analysis we adopt the same radial atomic labeling as in refs. 34 , 52 that is H 1 –C 2 –Si 3 (Ge 3 )–O 4 –Al 5 –O 6 –H 7 from the nanotube cavity to its outer surface (see Fig. 1 ).…”

Solid wetting-layers in inorganic nano-reactors: the water in imogolite nanotube case

“…S13 in the ESI, † such an increase of the Ge-INT's wall dipole density markedly affects the electrostatics inside the cavity with a $1.3 eV shi of the vacuum electrostatic plateau inside the nanotube's cavity. Given the increased m s for the pHyd Ge-INT with respect to the dry Ge-INT, and the calculated sensitivity of the electron acceptor/donor states of nano-conned species to the cavity electrostatics, 65,66 these results suggest that the pHyd Ge-INTs may be substantially more effective as redox co-catalysts than the pristine dehydrated Ge-INT.…”

Metal Chalcogenides Based Heterojunctions and Novel Nanostructures for Photocatalytic Hydrogen Evolution

“…More importantly, INTs present a real-space separation of the valence band and the conduction band edges, which may be beneficial for electron-hole (e − /h + ) separation via optical charge-transfer excitations across the nanotube walls [95]. The forward-looking improvement of e − /h + separation can therefore be effective in sustaining photocatalytic reactivity directly by the nanotube itself [96][97][98]. Although the computed VB and CB edges and the corresponding energy drive toward photoreduction (or photooxydation) appear to depend weakly on the nanotube diameter and the curvature, the separation of charges in methyl-modified INTs seems to be related to the nature of isomorphic substitution with respect to the inner cavity (Figure 15a,b) [73].…”