Photocatalytic properties of CuO/(001)‐TiO2 composites synthesized by the vapor–thermal method

Composites of (001)‐face‐exposed TiO₂ ((001)‐TiO₂) and CuO were synthesized in water vapor environment at 250°C with various Cu/Ti molar ratios (R_Cu/Ti). The resulting CuO/(001)‐TiO₂ composites were characterized using a variety of techniques. The synthesis under high‐temperature vapor allows close contact between CuO and (001)‐TiO₂, which results in the formation of heterojunctions, as evidenced by the shift of valence band maximum towards the forbidden band of TiO₂. An appropriate ratio of CuO can enhance the absorption of visible light and promote the separation of photogenerated carriers, which improve the photocatalytic performance. The degradation rate constant K_app increased from 5.5 × 10^?2 to 8.1 × 10^?2 min^?1 for R_Cu/Ti = 0.5. Additionally, the results showed that superoxide radicals (^?O₂^?) play a major role in the photocatalytic degradation of methylene blue.