Controlled synthesis of graphitic carbon nitride/beta bismuth oxide composite and its high visible-light photocatalytic activity

g-C3N4/β-Bi2O3 composites with high visible-light-driven photocatalytic activity were prepared through calcination of g-C3N4/Bi2O2CO3 of different proportions. They were characterized by powder X-ray diffraction (XRD), Fourier Translation infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy TEM (high resolution transmission electron microscopy HRTEM), UV–vis diffuse reflectance spectra (UV–vis DRS) and photoluminescence spectra (PL) techniques. It was observed that the phase structure of Bi2O3 is subject to the amount of g-C3N4 in the g-C3N4/Bi2O2CO3 precursor. Based on the results of light absorption and photocurrent measurement as well as the energy levels of β-Bi2O3 and g-C3N4, we propose a mechanism for the degradation of organic compounds over this class of catalysts.