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An interfacial lattice Ag(+) doped on TiO2 (Ag(+)/TiO2) was prepared by eluting Ag(0) clusters from a hydrothermally prepared Ag(0)/Ag(+)/TiO2 composite. An Ag(+)/TiO2@Ag(0) composite photocatalyst was subsequently obtained via a secondary Ag(0) clusters loading process to the Ag(+)/TiO2. The photocatalytic activity of Ag(+)/TiO2@Ag(0) was greatly improved compared to Ag(0)/Ag(+)/TiO2 and Ag(+)/TiO2. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) testing verified that Ag(+) ions occur as an interfacial lattice Ag(+) species in the composites. The enhancement effect of the interfacial lattice Ag(+) species is exhibited by the newly-formed Ag(+)/TiO2@Ag(0) as the interfacial lattice Ag(+) is fully exposed but not overlapped with the re-loaded Ag(0) clusters. The interfacial lattice Ag(+) ions and Ag(0) clusters are both responsible for the photocatalytic performance improvement of the catalyst, in either the photocatalytic degradation of methyl orange or photocurrent measurement.

Oxygenv acancies have ap ositive effect on the photocatalytic performance of TiO 2 ,b ut their benefits are deeplyl imited owing to their inherent lability.T oa void this disadvantage, fluorine atoms were used to "occupy" the surface oxygen vacancies (O vacancies) of TiO 2 .The "fluorine-occupied" surfaceOvacancies maintain the intrinsic nature of the Ov acancies, but they are stable under ambient and photocatalytic conditions. TiO 2 with "fluorine-occupied" surfaceOvacancies give enhanced performance in terms of both photodegradation and photocurrent conversion. The "occupied" strategy used herein holds promise to be ac ommon method for developing Ov acancy-related photocatalysts.Early works confirmed that doping of impurities into the sublattice of oxygen in TiO 2 is accompanied by the generation of Ov acancies, whichl eads to as ignificant enhancement in photocatalytic activity.T he impurity levels between the bandgap of TiO 2 are raised,a nd this is the main reason [1] why the photocatalytic activity is improved, whereas others argue that Ov acancy relatedc olorc enters as well as traps play important roles for the generation and separation of photocarriers.[2]As one important kind of defect site, Ov acancies (always accompanied by the creationo fT i 3 + centers) can act as absorption and active sites in heterogeneous catalytic reactions.[3] It was proven that Ov acancies have ag reat impact on electronic structure, charge transport, and other surface properties, all of which play roles in enhancing the photocatalytic performance of TiO 2 . [2, 3c, 4] Various Ov acancy related modified TiO 2 photocatalysts have been prepared, and they showe xtraordinary performance in many areas such as hydrogen production, water remediation, and photoelectric conversion under either UV-orv isible-light irradiation. [5] So far,Ovacancy singlym odified TiO 2 photocatalysts (also identified as Ti 3 + self-doped TiO 2 )a re usually obtained by placing bare TiO 2 in an oxygen-poor (e.g.,A ra tmosphere or vacuum) [3c, 6] or reductive environment. [5c, 7] Typically,t he two excess electrons on the Ov acancies interact with neighboring Ti 4 + ions to give three forms, that is,[2] However,t hese obtained Ov acancies remainr elatively unstablea nd can be easily recovered if catalysts are exposed to O 2 under thermalt reatment (T > 830 K) [8] or irradiation, [9] as the Ov acancies are easily reoccupied by Oa toms, which causes the disappearance of defect sites [10] and thus diminishes the benefits of Ov acancy doping.Herein, we report as ite-occupied strategy to stabilize the surfaced efects ites of the Ov acancies on the surface of TiO 2 . TiO 2 with as-modified defects ites thuss hows stable and enhanced photocatalytic performance. For experimental details, bare TiO 2 was first degassed under vacuum (0.93 Pa) at 350 8C to form the surfaceOvacancies [6a, 11] (referred to as V-TiO 2 ). Fluorine atoms were subsequently introduced to occupy the O vacancies by treating V-TiO 2 with a2 .0 m aqueous solution of NH 4 F, and an F-occupie...

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