Electronic properties of vanadium-doped TiO2.
The electronic properties of vanadium-doped rutile TiO(2) are investigated theoretically with a Hartree-Fock/DFT hybrid approach. The most common oxidation states (V(2+), V(3+), V(4+), and V(5+)) in different spin states are investigated and their relative stability is calculated. The most stable spin states are quartet, quintet, doublet, and singlet for V(2+), V(3+), V(4+), and V(5+) doping, respectively. By comparing the formation energy with respect to the parent oxides and gas-phase oxygen (ΔE), we conclude that V(4+) (ΔE=145.3 kJ mol(-1)) is the most likely oxidation state for vanadium doping with the possibility of V(5+) doping (ΔE=283.5 kJ mol(-1)). The energetic and electronic properties are converged with dopant concentrations in the range of 0.9 to 3.2%, which is within the experimentally accessible range. The investigation of electronic properties shows that V(4+) doping creates both occupied and unoccupied vanadium states in the band gap and V(5+) doping creates unoccupied states at the bottom of the conduction band. In both cases there is a significant reduction of the band gap by 0.65 to 0.75 eV compared to that of undoped rutile TiO(2).
Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstrasse 12, 53115 Bonn, Germany. rana-islam@thch.uni-bonn.de
Mazharul M
MM
Islam
Thomas
T
Bredow
Andrea
A
Gerson
D004583:Electrons; D010084:Oxidation-Reduction; D011789:Quantum Theory; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry*; D014639:Vanadium / Q000737:chemistry*
D014639:Vanadium; C009495:titanium dioxide; D014025:Titanium