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

A combined hydrothermal-calcination approach is developed to synthesize hierarchical β -Bi 2 O 3 /g-C 3 N 4 direct Z-scheme photocatalyst with enhanced visible light photoactivity for Rhodamine B (RhB) degradation. First, Bi 2 O 2 CO 3 microflowers were hydrothermally prepared using Bi(NO 3 ) 3 ·5H 2 O as feedstocks, and then a series of β -Bi 2 O 3 /g-C 3 N 4 direct Z-scheme photocatalysts were synthesized via a facile calcination method using Bi 2 O 2 CO 3 and g-C 3 N 4 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-C 3 N 4 content in the precursors played a key role in affecting the photocatalytic activity of the final products. The β -Bi 2 O 3 /g-C 3 N 4 heterojunction exhibited higher photocatalytic activity than single active components ( β -Bi 2 O 3 and g-C 3 N 4 ), indicating the presence of a synergistic effect between two active components in β -Bi 2 O 3 /g-C 3 N 4 heterojunction. Among all as-prepared catalysts, the 70 wt.% g-C 3 N 4 /Bi 2 O 2 CO 3 exhibits the highest activity for RhB degradation, and the apparent reaction rate constant k (42.2 × 10 −3  min −1 ) is 3.1 and 1.7 times as high as that of pure β -Bi 2 O 3 (13.5 × 10 −3  min −1 ) and g-C 3 N 4 (25.2 × 10 −3  min −1 ), respectively. The enhanced photocatalytic performance of β -Bi 2 O 3 /g-C 3 N 4 heterostructure photocatalysts is mainly due to the high surface area, closely contacted interfaces between the β -Bi 2 O 3 and g-C 3 N 4 component, and the formation of direct Z-scheme structure in the β -Bi 2 O 3 /g-C 3 N 4 composites.