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

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.