Synergistic effect of surface self-doping and Fe species-grafting for enhanced photocatalytic activity of TiO2 under visible-light

Abstract Surface grafting of transition-metal complexes or oxides is an appealing way to enhance the photocatalytic activity of TiO 2 under visible-light excitation. However, the performance of these co-catalysts assistant TiO 2 photocatalysts is still not sufficient enough due to their relatively weak visible-light absorption. Herein, we report a simple impregnation treatment with ferric ethoxide/ethanol solvent, followed with mild heating which can significantly enhance the visible-light absorption and photocatalytic activity of TiO 2 . XPS and EPR analyses manifest that the oxygen vacancies (V O s) and Fe-species are simultaneously introduced to the surface of TiO 2 . The chemical state and photocatalytic activity of the Fe-species-grafted TiO 2 − x is dependent on the heating temperature after impregnation. The sample heat-treated at 250 °C exhibits the optimal photocatalytic performance for β-naphthol degradation with rate constant 6.0, 2.7, and 3.9 times higher than that of TiO 2 , TiO 2 − x , and Fe-TiO 2 , respectively. The activity enhancement is discussed on the basis of the synergistic effect and energy-level matching of surface V O s and Fe-species co-catalyst, i.e. the V O s defects states increase the visible-light absorption and the Fe-species in the form of FeOOH promote the consumption of photo-generated electrons through multi-electron reduction of adsorbed molecule oxygen.