Ab initio study of oxygen point defects on tungsten trioxide surface

Abstract

The gas response of tungsten trioxide (WO 3) based sensors strongly depends on the surface properties. Reconstructed surfaces and oxygen point defects at the surface of the monoclinic WO 3 are studied using a self-consistent scheme based on first-principle. The oxygen vacancy is found to be the predominant defect independently of the oxygen partial pressure. Indeed, under rich oxygen atmosphere the formation enthalpies are found to be 1.45 eV in LDA (1.28 eV in GGA) for the oxygen vacancy instead of 2.70 eV (2.42 eV) for the oxygen adatom. When the oxygen partial pressure is lowered, the oxygen vacancy formation enthalpy decreases and becomes exothermic under very O-poor condition (-1.65 eV in LDA and-1.36 eV in GGA). On the other hand, the formation enthalpy of an oxygen adatom rises. Finally, the oxygen vacancy formation acts as a n-doping by introducing negative charge carriers at the bottom of the conduction band. All these results can be very helpful in order to explain the electrical resistivity measurements.

Anisotropic Effects of Oxygen Vacancies on Electrochromic Properties and Conductivity of γ-Monoclinic WO3

“…40 From the theoretical side, density-functional theory (DFT) has been widely applied to the study of O deficient WO 3 (WO 3−x ). [41][42][43][44][45] In particular, the hybrid functional DFT calculations in O deficient and lithium doped γ-WO 3 using the DFT + U method. 45 Both methodologies have proved to describe in at least a qualitatively correct way ground state properties (in particular, charge localization) and the electronic structure.…”

DFT study on interaction of NO2 with the vacancy-defected WO3 nanowires for gas-sensing

“…Tungsten trioxide (WO 3 ), which is a wide band-gap n-type semiconductor [1], has been experimentally proved to be a promising gas-sensing material for sensitive detection of various toxic and dangerous gases, such as NO x [2,3], NH 3 [3,4] and CO [3,5,6] and so on. So far, considerable progress has been made in the experimental studies about preparation and gas-sensing properties of WO 3 , especially one-dimensional (1D) nanowires.…”

Polaron mobility in oxygen-deficient and lithium-doped tungsten trioxide

“…More studies of the electronic and structural properties of perfect and defective W O 3 can be found in Refs. [52,[54][55][56][57]. Despite intensive research many questions regarding the properties of polarons in W O 3 remain unclear.…”