Electronic Properties of Vanadium‐Doped TiO₂

Abstract

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).

Greatly Enhanced Electrocatalytic N2 Reduction on TiO2 via V Doping

“…The DFT investigation by Kim et al also shows that V atom replaces a fivefold coordinated surface Ti atom in rutile TiO 2 (110) surface (namely V 2 doping site) to interact with gas molecule such as CO and O 2 , which further confirms that V 2 doping surface is reasonable for NRR process. Density of states (DOS) show that it creates both occupied and unoccupied V 3d states in the bandgap in Figure S19 (Supporting Information), corresponding to the magnetic V 4+ species (3d 1 ), consistent with Islam et al's work. Importantly, N 2 molecule more prefers to adsorb on V 2‐2 site than V 2‐1 site, which may be attributed to that the former possesses structure distortion with TiO bond changing from 1.97 to 1.98 Å (Figure S20, Supporting Information).…”

Low‐Temperature Synthesis, Characterization, and Stability of Spinel‐Type Li2NiF4 and Solid‐Solutions Li2Ni1–xCoxF4

“…The thermodynamic stability of Li 2 Ni 1– x Co x F 4 ( x = 0, 0.125, 0.25, 0.5, 1) was studied theoretically at density‐functional theory (DFT) level. Based on our experience with open‐shell transition metal compounds25 we used the DFT‐Hartree‐Fock hybrid functional PW1PW 26. The calculations were performed with the crystalline‐orbital program package CRYSTAL09 27.…”

Synthesis of ternary transition metal fluorides Li3MF6via a sol–gel route as candidates for cathode materials in lithium-ion batteries

“…Based on our experience with open-shell transition metal systems 39 we chose the DFT/Hartree-Fock hybrid functional PW1PW. 40 The calculations were performed with the crystalline-orbital program package CRYSTAL09.…”