Theoretical Study of α‐V₂O₅‐Based Double‐Wall Nanotubes

Abstract

First-principles calculations of the atomic and electronic structure of double-wall nanotubes (DWNTs) of α-V2 O5 are performed. Relaxation of the DWNT structure leads to the formation of two types of local regions: 1) bulk-type regions and 2) puckering regions. Calculated total density of states (DOS) of DWNTs considerably differ from that of single-wall nanotubes and the single layer, as well as from the DOS of the bulk and double layer. Small shoulders that appear on edges of valence and conduction bands result in a considerable decrease in the band gaps of the DWNTs (up to 1 eV relative to the single-layer gaps). The main reason for this effect is the shift of the inner- and outer-wall DOS in opposite directions on the energetic scale. The electron density corresponding to shoulders at the conduction-band edges is localized on vanadium atoms of the bulk-type regions, whereas the electron density corresponding to shoulders at the valence-band edges belongs to oxygen atoms of both regions.

Theoretical study of α- and γ-V2O5 double-walled nanotubes

“…In the α-DWNTs the structure of adhesion regions is similar to the structure of the bulk α-V 2 O 5 [13] ( Fig. 3).…”

“…In most cases, the observed vanadium pentoxide nanotubes are multi-walled. In our previous work [13] we investigated the atomic and electronic structure of DWNTs obtained from the α-V 2 O 5 phase. Here we present the results of the study of γ-V 2 O 5 DWNTs and compare them with those of α-V 2 O 5 ones.…”

Thermal activation of charge carriers in ionic and electronic semiconductor β-AgIVVO3 and β-AgIVVO3@VV1.6VIV0.4O4.8 composite xerogels

“…[27][28][29] VO nanotubes are able to adapt the vanadium interlayer space and vanadium oxidation state to the amine and ionic interlayer species, and these parameter have a drastic inuence on their electric properties. [30][31][32][33][34] These layered structural architectures are repeated in other mixed valence vanadium oxides such as V 2 O 5 $H 2 O xerogels, 27 BaV 3 O 7 , TMAV 3 O 7 , just to mention some of the multiple examples found in the literature. In general, the electron conduction of mixed valence vanadium oxides is governed by the electron hopping mechanism.…”

“…7 (a) Arrhenius plot for H0A10 and H1A10 xerogels during the 1 st heating treatment and (b) Arrhenius plot for H0A10 xerogel in two heating and cooling cycles. (30) used in the measurements. Impedance complex data were recorded for successive heating/cooling cycles; which show some irreversibility during cooling.…”

Electrochemically Generated γ‐LixV2O5 as Insertion Host for High‐Energy Li‐Ion Capacitors

“…Five crystalline phasesn amed a, e, d, g,a nd w are formed during lithiation, whichi sb ased on the amount of Li ion uptake (value of x). Importantly,t he reversibility completely depends on the testing potential, [40] for example, the Li-insertion (Li x V 2 O 5 )a t% 3.4, % 3.2 and % 2.3 Vv s. Li corresponds to the formation of a/e, e/d,a nd d/g two-phase regions,r espectively.G enerally,t he d phase occurs at the value of x = 1, and there is also as udden drop in cell potential. [41,42] The transition of d to g phase can be reversibly cycled in the range of 1 < x < 2w hile preserving its structure.…”