Zn-Assisted TiO_2–<i>x</i> Photocatalyst with Efficient Charge Separation for Enhanced Photocatalytic Activities

A new Zn-assisted method has been employed to synthesize reduced TiO₂(TiO_2–<i>x</i>) photocatalyst via a one-step hydrothermal process. In order to prevent the oxidation of TiO_2–<i>x</i> in air, hydrofluoric acid is introduced in the preparative process for the stabilization of the Ti³⁺ and oxygen vacancies, as confirmed by low-temperature electron paramagnetic resonance. The obtained reduced TiO₂ presents a wide-spectrum solar light absorption, including the near-infrared region. In addition, {110}–{111} and {101}–(001) dual-facet exposures are generated by Cl- and F-based surface-terminated reagents, respectively. The generated {001} and {101} facets on reduced TiO₂ samples act as hole and electron collectors, respectively, which contributes to the charge separation of the catalyst. Finally, the synergistic effect between Ti³⁺ doping and dual-facet exposure results in the high photocatalytic performance for degradation of Rhodamine B and formic acid