Oxygen vacancies enable the visible light photoactivity of chromium-implanted TiO2 nanowires

Although computational studies have demonstrated that metal ion doping can effectively narrow the bandgap of TiO2, the visible-light photoactivity of metal-doped TiO2 photoanodes is still far from satisfactory. Herein, we report an effective strategy to activate the visible-light photoactivity of chromium-implanted TiO2 via the incorporation of oxygen vacancies. The chromium-doped TiO2 activated by oxygen vacancies (Cr-TiO2-vac) exhibited an incident photon-to-electron conversion efficiency (IPCE) of ~6.8% at 450 nm, which is one of the best values reported for metal-doped TiO2. Moreover, Cr-TiO2-vac showed no obvious photocurrent decay after 100 h under visible-light illumination.