Fabrication of flower-like direct Z-scheme beta-Bi2O3/g-C3N4 photocatalyst with enhanced visible light photoactivity for Rhodamine B degradation

A combined hydrothermal-calcination approach is developed to synthesize hierarchical beta-Bi2O3/g-C3N4 direct Z-scheme photocatalyst with enhanced visible light photoactivity for Rhodamine B (RhB) degradation. First, Bi2O2CO3 microflowers were hydrothermally prepared using Bi(NO3)(3)center dot 5H(2)O as feedstocks, and then a series of beta-Bi2O3/g-C3N4 direct Z-scheme photocatalysts were synthesized via a facile calcination method using Bi2O2CO3 and g-C3N4 as precursors. The samples were systematically characterized by various characterization technologies including X-ray diffraction, scanning and transmission electron microscopes, Fourier transform infrared spectroscopy and N-2 absorption-desorption equipment. It was found that the g-C3N4 content in the precursors played a key role in affecting the photocatalytic activity of the final products. The beta-Bi2O3/g-C3N4 heterojunction exhibited higher photocatalytic activity than single active components (beta-Bi2O3 and g-C3N4), indicating the presence of a synergistic effect between two active components in beta-Bi2O3/g-C3N4 heterojunction. Among all as-prepared catalysts, the 70 wt.% g-C3N4/Bi2O2CO3 exhibits the highest activity for RhB degradation, and the apparent reaction rate constant k (42.2 x 10(-3) min(-1)) is 3.1 and 1.7 times as high as that of pure beta-Bi2O3 (13.5 x 10(-3) min(-1)) and g-C3N4 (25.2 x 10(-3) min(-1)), respectively. The enhanced photocatalytic performance of beta-Bi2O3/gC(3)N(4) heterostructure photocatalysts is mainly due to the high surface area, closely contacted interfaces between the beta-Bi2O3 and g-C3N4 component, and the formation of direct Z-scheme structure in the beta-Bi2O3/g-C3N4 composites. (C) 2017 Elsevier B.V. All rights reserved.