title: Band gap narrowing of titanium oxide semiconductors by noncompensated anion-cation codoping for enhanced visible-light photoactivity.
abstract: "Noncompensated n-p codoping" is established as an enabling concept for enhancing the visible-light photoactivity of TiO2 by narrowing its band gap. The concept embodies two crucial ingredients: the electrostatic attraction within the n-p dopant pair enhances both the thermodynamic and kinetic solubilities, and the noncompensated nature ensures the creation of tunable intermediate bands that effectively narrow the band gap. The concept is demonstrated using first-principles calculations, and is validated by direct measurements of band gap narrowing using scanning tunneling spectroscopy, dramatically redshifted optical absorbance, and enhanced photoactivity manifested by efficient electron-hole separation in the visible-light region. This concept is broadly applicable to the synthesis of other advanced functional materials that demand optimal dopant control.
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Wenguang
authors.initials: W
authors.lastname: Zhu
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Qiu
authors.forename: Violeta
authors.initials: V
authors.lastname: Iancu
authors.forename: Xing-Qiu
authors.initials: XQ
authors.lastname: Chen
authors.forename: Hui
authors.initials: H
authors.lastname: Pan
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Nada M
authors.initials: NM
authors.lastname: Dimitrijevic
authors.forename: Tijana
authors.initials: T
authors.lastname: Rajh
authors.forename: Harry M
authors.initials: HM
authors.lastname: Meyer
authors.forename: M Parans
authors.initials: MP
authors.lastname: Paranthaman
authors.forename: G M
authors.initials: GM
authors.lastname: Stocks
authors.forename: Hanno H
authors.initials: HH
authors.lastname: Weitering
authors.forename: Baohua
authors.initials: B
authors.lastname: Gu
authors.forename: Gyula
authors.initials: G
authors.lastname: Eres
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Zhang