Enhancement of visible-light photocatalytic activities of BiVO 4 coupled with g-C 3 N 4 prepared using different precursors

Abstract

Graphitic-like carbon nitride (g-C₃N₄) photocatalyst was synthesized by a facile chemical pyrolysis method, which was built on the self-condensation of different precursors to generate g-C₃N₄, e.g., melamine, urea, and thiocarbamide. And the different precursors produced a great influence on the photocatalytic activities of g-C₃N₄. Heterojunctions of g-C₃N₄ and BiVO₄ were synthesized using a facile solvent evaporation method. The formation of BiVO₄/g-C₃N₄ composites were confirmed by XRD, FT-IR, SEM, XPS, and UV-Vis DRS. The photocatalytic activities for RhB degradation were evaluated under visible-light irradiation. The photocatalytic activity of g-C₃N₄ prepared by urea was higher than that of g-C₃N₄ prepared by melamine and thiocarbamide, which was attributed to its favorable dispersibility, larger specific surface area, and higher oxidation capacity. The heterojunction composites exhibited higher photocatalytic activity than pure g-C₃N₄ or BiVO₄. The results showed obvious removal efficiency for RhB, and the optimal sample with a BiVO₄ content of 10% exhibited higher efficiency than pure g-C₃N₄ and BiVO₄, and 10 wt%BiVO₄/CN-U showed the highest photocatalytic activity. The enhanced photocatalytic activity of BiVO₄/g-C₃N₄ composite can be attributed to the intimate coupling between the two host substrates, resulting in an efficient charge separation.