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Metal doping has long been recognized as a general strategy to modify electronic properties of semiconductors. The purpose here is to understand the behavior of oxygen vacancy when existing together with a metal dopant in rutile TiO2 through first‐principles calculation. For the coexistence of an oxygen vacancy and an Ag/Hf dopant, the dopant local effect determines that the formation energy of the oxygen vacancy depends on distances from it to the Ag/Hf dopant. Increased formation energy of an oxygen vacancy adjacent to an Ag dopant is attributed to the fact that the holes produced because of lower valence of Ag than Ti are filled by electrons left by the oxygen vacancy. The same valence of Hf as Ti results in that the electrostatic repulsive force pushes the Hf dopant outward from nearby oxygen vacancy, which lowers the formation energy of the oxygen vacancy. Furthermore, oxygen vacancies coexisting with an Ag/Hf dopant are of interest for investigating the effect of metal doping on the reliability of conductive filaments. The Hf dopant adjacent to the oxygen vacancies greatly enhances the strength of a conductive filament. The built‐in electric fields from localized electrons are considered as the seed action of metal doping in resistive switching devices. [ABSTRACT FROM AUTHOR]

The effect of Cu/O/Ti interstitials on the visible-light absorption in Cu2O/TiO2 heterojunctions has been investigated by ab initio methods. The three interstitials are, respectively, doped at the interface of the Cu2O/TiO2 heterojunctions. The Ti interstitial efficiently improves the visible-light absorption, whereas the O interstitial reduces the visible-light absorption. An independent characteristic of the visible-light absorption is found for doping with the Cu interstitial. These phenomena originate from the different concentrations of delocalized electrons induced by the doping atom. The doping with Ti atoms could induce the aggregation of Cu ions, which release more delocalized electrons and so improve the visible-light absorption in a Cu2O/TiO2 heterojunction. [ABSTRACT FROM AUTHOR]

The properties and behavior of a single Au atom supported anatase TiO2(001) surface are calculated using density functional theory (DFT) methods. The structures and energies of adsorbed single Au on an anatase TiO2(001) surface with surface oxygen vacancy, as well as subsurface oxygen vacancy, are systematically determined. Initially, the surface threefold coordinated oxygen vacancy adjacent to a single Au atom, rather than the surface two‐fold coordinated oxygen vacancy and subsurface threefold coordinated oxygen vacancy, results in more stability for anatase TiO2(001) surface with an Au adatom. Afterwards, the CO molecule is more strongly adsorbed on the single Au‐supported TiO2(001) surface with surface threefold coordinated oxygen vacancy when comparing to other structures. This is attributed to the more negatively charged Au single‐atom caused by a surface threefold coordinated oxygen vacancy presents concededly active for CO adsorption. The structures and energies of adsorbed single Au on anatase TiO2(001) surface with various oxygen vacancies are systematically addressed. The surface oxygen vacancy adjacent the adsorbed atomic Au increased the stability of atomic Au and further improved the adsorption of CO molecules. This is attributed to the oxygen vacancy above resulting in the presence of a charge reservoir in atomic Au. [ABSTRACT FROM AUTHOR]