Z-scheme g-C3N4/BiVO4 photocatalysts with RGO as electron transport accelerator

Abstract

BiVO4 is known for its ability to decompose water under visible light irradiation. However, BiVO4 overall suffers from rapid recombination of photogenerated carriers, low photochemical conversion efficiency, low specific surface area, poor conductivity, and weak adsorption capacity of dye. These features limited its application in photocatalysis. In this work, ternary Z-scheme g-C3N4/RGO/BiVO4 nanocomposites were successfully fabricated by in situ electrostatic adsorption of g-C3N4 sheets on RGO/BiVO4 surface using hydrothermal and thermal oxidations processes. The ternary Z-scheme g-C3N4/RGO/BiVO4 nanocomposites were then tested for photodegradation of Rhodamine B. The introduction of graphene into direct Z-scheme g-C3N4/BiVO4 nanocomposites as an electronic accelerator efficiently enhanced the photocatalytic properties. The as-prepared g-C3N4/RGO/BiVO4 composites exhibited optimal visible light responses with significantly improved photocatalytic performances toward degradation of Rhodamine B. The degradation efficiency using ternary photocatalyst reached 100% after 20 min of irradiation time. The reaction rate constant was estimated to 1.537, which was almost 29- and 20-folds higher than those of pure g-C3N4 and binary g-C3N4/BiVO4, respectively. The synergistic effect between BiVO4, RGO and g-C3N4 yielded g-C3N4/RGO/BiVO4 composites with Z-scheme charge transfer mechanism, promoting rapid separation and slow recombination of photogenerated electron–hole pairs with strong photocatalytic activity. Overall, these findings look promising for design of future Z-scheme photocatalysts for environmental degradation of organic dyes.