Fabrication of g-C3N4/Bi2WO6 as a direct Z-scheme excellent photocatalyst

Abstract

To improve the photocatalytic efficiency of Bi₂WO₆, two types of g-C₃N₄ nanomaterial, g-C₃N₄ quantum dots and g-C₃N₄ nanosheets, were incorporated with Bi₂WO₆ to construct two kinds of g-C₃N₄/Bi₂WO₆ Z-scheme photocatalysts with excellent photocatalytic activity. The results showed that the g-C₃N₄ quantum dots were uniformly distributed over the whole surface of Bi₂WO₆, inhibited the Bi₂WO₆ sheets from growing, and resulted in high specific surface area and more active sites. Conversely, the stronger electrostatic interaction between g-C₃N₄ and Bi₂WO₆ nanosheets led to the formation of a dense and uniform flower-like structure with small specific surface area. All the g-C₃N₄/Bi₂WO₆ composites showed higher photocatalytic activities than pure Bi₂WO₆. The g-C₃N₄ quantum dots/Bi₂WO₆ composite showed better photocatalytic activities towards the degradation of organic dyes, such as methylene blue and acid fuchsin, while the g-C₃N₄ nanosheets/Bi₂WO₆ composite showed better photocatalysis decomposition of antibiotics including ciprofloxacin and tetracycline. The enhanced photocatalytic activity of the g-C₃N₄/Bi₂WO₆ composites under sunlight irradiation could be ascribed to a Z-scheme mechanism based on the radical trapping experiments and electron spin resonance, thereby revealing that the holes played a major role in photocatalytic performance.