Short-Time Hydrothermal Synthesis of CuBi₂O₄ Nanocolumn Arrays for Efficient Visible-Light Photocatalysis

In this article, a short-time hydrothermal method is developed to prepare CuBi₂O₄ nanocolumn arrays. By using Bi(NO₃)₃·5H₂O in acetic acid and Cu(NO₃)₂·3H₂O in ethanol as precursor solutions, tetragonal CuBi₂O₄ with good visible light absorption can be fabricated within 0.5 h at 120 °C. Tetragonal structured CuBi₂O₄ can be formed after 15 min hydrothermal treatment, however it possesses poor visible light absorption and low photocatalytic activity. Extending the hydrothermal treatment duration to 0.5 h results in a significant improvement invisible light absorption of the tetragonal CuBi₂O₄. The CuBi₂O₄ obtained through 0.5 h hydrothermal synthesis shows a band gap of 1.75 eV and exhibits the highest photocatalytic performance among the CuBi₂O₄ prepared with various hydrothermal time. The removal rate of methylene blue by the 0.5 h CuBi₂O₄ reaches 91% under visible light irradiation for 0.5 h. This study proposes a novel strategy to prepare photoactive CuBi₂O₄ nanocolumn arrays within 0.5 h at a moderate temperature of 120 °C. The hydrothermal method provides a facile strategy for the fast synthesis of metal-oxide-based photocatalysts at mild reaction conditions.