TY - JOUR

T1 - Water adsorption on α-V2O5 surface and absorption in V2O5∙nH2O xerogel

T2 - DFT study of electronic structure

AU - Porsev, Vitaly V.

AU - Bandura, Andrei V.

AU - Evarestov, Robert A.

PY - 2017/12/1

Y1 - 2017/12/1

N2 - Adsorption of water on (001)-terminated α-V2O5 surface has been investigated in the framework of density functional theory. According to our calculations, molecular adsorption is preferred, and two types of adsorption sites (Lewis acid center on V atom and Lewis base center on O atoms) have been found. Water adsorption on Lewis acid site does not change the electronic structure of V2O5 surface. Adsorption on Lewis base site is less favorable but reduces the band gap value by half (from 2.5 to 1.3 eV). The reason of this decreasing is the localization of the non-bonding 1b2 electron state of water molecule within the forbidden gap of V2O5 surface. The idealized structure of V2O5∙nH2O xerogel has been computationally studied at n = 0 and 1. It is proved that only Lewis base sites are suitable for water positions. At n = 1, the water absorption energy in xerogel is close to adsorption energy of water on the oxygen atoms of α-V2O5 surface. The presence of the non-bonding states of physically absorbed water in the forbidden gap is also found in the xerogel case. This results in decreasing of the band gap from 2.7 eV to 0.7 eV.

AB - Adsorption of water on (001)-terminated α-V2O5 surface has been investigated in the framework of density functional theory. According to our calculations, molecular adsorption is preferred, and two types of adsorption sites (Lewis acid center on V atom and Lewis base center on O atoms) have been found. Water adsorption on Lewis acid site does not change the electronic structure of V2O5 surface. Adsorption on Lewis base site is less favorable but reduces the band gap value by half (from 2.5 to 1.3 eV). The reason of this decreasing is the localization of the non-bonding 1b2 electron state of water molecule within the forbidden gap of V2O5 surface. The idealized structure of V2O5∙nH2O xerogel has been computationally studied at n = 0 and 1. It is proved that only Lewis base sites are suitable for water positions. At n = 1, the water absorption energy in xerogel is close to adsorption energy of water on the oxygen atoms of α-V2O5 surface. The presence of the non-bonding states of physically absorbed water in the forbidden gap is also found in the xerogel case. This results in decreasing of the band gap from 2.7 eV to 0.7 eV.

KW - Adsorption, water

KW - Band gap

KW - DFT

KW - Electron density of states

KW - VO

KW - Xerogel

UR - http://www.scopus.com/inward/record.url?scp=85029043140&partnerID=8YFLogxK

U2 - 10.1016/j.susc.2017.08.022

DO - 10.1016/j.susc.2017.08.022

M3 - Article

AN - SCOPUS:85029043140

VL - 666

SP - 76

EP - 83

JO - Surface Science

JF - Surface Science

SN - 0039-6028

ER -