Defect processes in F and Cl doped anatase TiO2

Abstract

Titanium dioxide represents one of the most widely studied transition metal oxides due to its high chemical stability, non-toxicity, abundance, electron transport capability in many classes of optoelectronic devices and excellent photocatalytic properties. Nevertheless, the wide bang gap of pristine oxide reduces its electron transport ability and photocatalytic activity. Doping with halides and other elements has been proven an efficient defect engineering strategy in order to reduce the band gap and maximize the photocatalytic activity. In the present study, we apply Density Functional Theory to investigate the influence of fluorine and chlorine doping on the electronic properties of TiO2. Furthermore, we present a complete investigation of spin polarized density functional theory of the (001) surface doped with F and Cl in order to elaborate changes in the electronic structure and compare them with the bulk TiO2.

Structural, Electronic, and Optical Properties of Group 6 Doped Anatase TiO2: A Theoretical Approach

“…Focusing on the DOS graph, the bandgap is estimated at 3.04 eV for the Cr i and 3.09 eV for the Cr Ti cases (Figure 2a,b). The bandgap of perfect anatase is calculated at 3.12 eV (shown in Figure 2g as a reference), which agrees with other theoretical studies and already published reports that show experimental values for the bandgap at 3.2 eV [27,33,34,50].…”

“…It belongs to the tetragonal I4/amd space group and its lattice parameters are measured to be a = 3.782 Å, b = 3.782 Å, and c = 9.502 Å [46]. Herein, the DFT calculated lattice parameters are a = 3.804 Å, b = 3.804 Å, and c = 9.729 Å, which agree with previous theoretical studies [8,34,47]. The dopants' percentage was 1 X (=Cr, Mo, W) atom per 108 TiO2 atoms, which results in a 0.92% doping percentage.…”

“…Transition metal oxides such as TiO2, tin oxide (SnO2), and zinc oxide (ZnO) represent an important class of materials due to their chemical stability, photocatalytic properties, and high electrical conductivity [1][2][3][4][5][6][7][8][9][10]. Anatase TiO2 has been widely investigated as a photocatalyst and as a solar cell material due to its intense absorption in the ultra-violet wavelength region [1][2][3][4][5][6][7].…”

“…Anatase TiO2 has been widely investigated as a photocatalyst and as a solar cell material due to its intense absorption in the ultra-violet wavelength region [1][2][3][4][5][6][7]. Furthermore, it has been long established as an effective electron transport layer (ETL) in dye-sensitized solar cells (DSSCs) and recently in organic (OSCs) and perovskite solar cells (PSCs) [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. The bandgap of anatase TiO2, which is around 3.2 eV [26,27], reduces its absorption in the near-infrared and visible region [7].…”

“…To decrease its bandgap and tune the electronic and optical properties, doping with appropriate elements is beneficial. A considerable variety of literature reports demonstrate that doping of anatase TiO2 with halogens, nitrogen, or transition metal ions such as zinc (Zn) significantly changes the electronic and optical properties [28][29][30][31][32][33][34]. For instance, when we dope TiO2 with chlorine (Cl) or nickel (Ni), the bandgap is reduced to 3 and 2.6 eV, respectively [33,34].…”