Ag-induced anatase-rutile TiO2−x heterojunction facilitating the photogenerated carrier separation in visible-light irradiation.

Nanocomposites Ag-TiO 2−x have been fabricated simply by Ag+ ion exchange of H 2 Ti 3 O 7 nanowires. Ag NPs, appearing on the catalyst surface, exhibit strong visible-light absorption and generate hot electrons due to their localized surface plasmon resonance. Moreover, Ag introduction leads to the generation of anatase-rutile biphase heterojunction with Ti3+ defect energy level, narrowing the bandgap to 2.85 eV and inhibiting the recombination of electron-hole pairs, thus facilitating photocatalytic reduction of Cr (VI) under visible light. A possible photocatalytic reduction mechanism, i. e., the synergistic effect of the Ti3+ defect energy level, anatase-rutile heterojunction and SPR effect of Ag nanoparticles, has also been proposed. [Display omitted] • Ag decorated anatase rutile heterojunction Ag-TiO 2-x nanowires were prepared by a simple ion-exchange strategy. • Intensive interfacial contact between Ag NPs, anatase and rutile phase promotes the separation of electron-hole pairs. • Synergistic effect of Ag SPR and defect sites of Ti3+ in TiO 2 biphase increases the utilization of visible light. • Ag-TiO2-x shows good photocatalytic reduction efficiency for Cr (VI) under visible light irradiation. [ABSTRACT FROM AUTHOR]