Synthesis of CuO_x/TiO₂ Photocatalysts with Enhanced Photocatalytic Performance

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.