Abstract
CuO x /TiO2 co-photocatalysts with various Cu loading contents were synthesized by an impregnation method, and their photocatalytic activities were evaluated by photodegradation of organic pollutants under visible light illumination. The as-prepared CuO x /TiO2 composites exhibited a unique structure, in which CuO x clusters with about 2-3 nm nanocrystals were uniformly distributed on the TiO2 cube. The mesoporous Ti3+/TiO2 substrate with a uniform pore structure greatly improved the uniformity of the loaded Cu, wherein Ti3+ acted as a reducing agent for reducing Cu2+ to Cu+ and Cu0. The reversible process of the Cu species between Cu+ and Cu0 markedly enhanced the photocatalytic activity of the CuO x /TiO2 co-photocatalyst, by promoting the transfer of photogenerated electrons and suppressing the recombination of photogenerated electron and hole pairs. The synergistic effect between CuO x and TiO2 also played an important role in enhancing the photocatalytic activity of the CuO x /TiO2 co-photocatalyst. The results indicated that CuO x /TiO2-1 had the highest photocatalytic efficiency, which was 1.5 times higher than that of the commercial nano-TiO2 P25 under visible light, and demonstrated a good stability even after five recycles. This structural design and the valence control strategy for the Cu atom provide an idea that facilitates the utilization of visible light and the improvement of the photocatalytic activity of TiO2, promoting the practical application of the TiO2 photocatalyst.