2D Slab Models of Nanotubes Based on Tetragonal TiO2 Structures: Validation over a Diameter Range

Abstract

One-dimensional nanomaterials receive much attention thanks to their advantageous properties compared to simple, bulk materials. A particular application of 1D nanomaterials is photocatalytic hydrogen generation from water. Such materials are studied not only experimentally, but also computationally. The bottleneck in computations is insufficient computational power to access realistic systems, especially with water or another adsorbed species, using computationally expensive methods, such as ab initio MD. Still, such calculations are necessary for an in-depth understanding of many processes, while the available approximations and simplifications are either not precise or system-dependent. Two-dimensional models as an approximation for TiO2 nanotubes with (101) and (001) structures were proposed by our group for the first time in Comput. Condens. Matter journal in 2018. They were developed at the inexpensive DFT theory level. The principle was to adopt lattice constants from an NT with a specific diameter and keep them fixed in the 2D model optimization, with geometry modifications for one of the models. Our previous work was limited to studying one configuration of a nanotube per 2D model. In this article one of the models was chosen and tested for four different configurations of TiO2 nanotubes: (101) (n,0), (101) (0,n), (001) (n,0), and (001) (0,n). All of them are 6-layered and have rectangular unit cells of tetragonal anatase form. Results of the current study show that the proposed 2D model is indeed universally applicable for different nanotube configurations so that it can be useful in facilitating computationally costly calculations of large systems with adsorbates.

Time-Dependent Density Functional Theory Calculations of N- and S-Doped TiO2 Nanotube for Water-Splitting Applications

“…As it is reported in the literature, the absorption spectrum of TiO 2 NT can be slightly blueshifted in comparison with TiO 2 thin films[39] and powders[40]. The blueshift of the absorption spectrum is well pronounced for the pristine TiO 2 NT.Our group has previously studied the anatase (n,0) TiO 2 (001) NT and anatase (0,n) TiO 2 (101) NTs[13][14][15]43] by means of ground state total energy calculations. In this work, the pristine TiO 2 NT is rolled up from the anatase TiO 2 (101) 6-layered slab.…”

“…Our group has previously studied the anatase (n,0) TiO 2 (001) NT and anatase (0,n) TiO 2 (101) NTs [13][14][15]43] by means of ground state total energy calculations. In this work, the pristine TiO 2 NT is rolled up from the anatase TiO 2 (101) 6-layered slab.…”

Application of Spinel and Hexagonal Ferrites in Heterogeneous Photocatalysis

“…In addition to the above-mentioned issues in the field of photocatalysis, attention should be paid to the fact that scientific knowledge in the subject of ab initio is still insufficient, as pointed out by, among others, Lisovski et al [44]. Ab initio is a computational chemistry method based on quantum chemistry, and in the case of a photocatalyst, it enables determination of, among others, exciton lifetimes, stability, the redox position of valence and conduction bands, bandgap, and adsorption energies.…”