IMPROVED PHOTOCATALYTIC PROPERTIES OF FLOWER-LIKE Bi2O2CO3/TiO2 NANOCOMPOSITE STRUCTURES

In this paper, hierarchical composites of TiO2 nanoparticles supported on flower-like spherical Bi2O2CO3 structures were synthesized by a two-step hydrothermal method. The prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectrometry (DRS), photoluminescence (PL) and photocurrent measurement. The photocatalytic activity of the composites was investigated as a function of the amount of TiO2 in the degradation of RhB under UV-Vis light irradiation. The Bi2O2CO3/TiO2 composites exhibited significantly enhanced performance compared with pure Bi2O2CO3 or TiO2. For instance, the Bi2O2CO3/TiO2 composite with 0.44 mL tetrabutyl titanate addition (i.e. BT-2) showed the best photocatalytic activity, which is about 3.7 times and 4.3 times as high as that of pure TiO2 or Bi2O2CO3, respectively. The improved performance of the Bi2O2CO3/TiO2 composites can be attributed to the formation of binary heterojunctions, which facilitate separation of photogenerated electron-hole pairs. Furthermore, the composites showed high stability and long-term reusability. To better understand the photocatalytic mechanism, experiments involving active species trapping were conducted, revealing that the holes and hydroxyl radicals played key roles in the photocatalytic reaction process.