The Energetic and Electronic Properties of 4d Transition Metals Doped TiO2 from First-Principles

• Key Words:4d Transition Metals; Doped TiO2; Electronic Properties; Red-Shift
• Abstract:First-principles density functional theory (DFT) calculations were performed to explore the effect of substitutional 4d transition metals (TM) on the electronic properties of anatase TiO2. The defect formation energies, the band structures and the density of states were calculated to analyze the energetic properties and electronic structures of 4d TM doped TiO2. TM doping is energetically favored in O-rich growth conditions with respect to Ti-rich growth conditions. Further more, the doping is energetically favorable and becomes easy in the order of Cd < Ag < Pd < Rh < Ru < Mo <Y < Nb < Zr. TM doping has impact on the electronic properties of TiO2. There are local impurity states between the valence band (VB) and the conduction band (CB) for Ag, Pd, Rh and Ru doped TiO2, respectively. The localized intermediated states play as "springboard," which makes the electronic transition from VB to CB become easy. However, the impurity states, introduced by TM (Y, Zr, Nb, Mo, or Cd) doping, don't appear between VB and CB, but hybridize with O 2p or Ti 3d states. They pull down the bottom of CB and narrow the energy gap. The reduction values of the energy gap are 0.05, 0.04, 0.06, 0.31 and 0.22 eV, respectively, corresponding to the electron transition energy from the VB to the CB decreasing. In addition, redshift can be observed in the absorption spectra for all TM doped anatase TiO2. The theoretical analysis might provide a probable reference for the experimentally element-doped TiO2 synthesis.
• Volume:9
• Issue:12
• Translation or Not:no