2D-Bi₂MoO₆/2D-g-C₃N₄ nanosheet heterojunction composite: synthesis and enhanced visible light photocatalytic mechanism

Abstract

In this study, a novel 2D Bi2MoO6 nanosheet/2D g-C3N4 nanosheet heterojunction composite was fabricated through a hydrothermal strategy. Afterwards, physicochemical properties of the composite were systematically detected by a series of measurements. In addition, photocatalytic activity was evaluated by the degradation of rhodamine B, methylene blue, Amido black 10B and malachite green. The results showed that Bi2MoO6/g-C3N4 possessed higher photocatalytic efficiency than that of the pristine Bi2MoO6 and g-C3N4 sample under visible irradiation. This phenomenon could be attributed to the combination of Bi2MoO6 and g-C3N4 as well as the unique 2D/2D heterostructure. Also, the as-fabricated Bi2MoO6/g-C3N4 composite possessed higher surface area, narrower bandgap energy, larger electron transport capability and longer charge carrier lifetime. Furthermore, the enhanced visible-light-driven photocatalytic mechanism was proposed and confirmed, which was mainly ascribed to the Z-scheme structure. That is, the photogenerated electrons (e(-)) in the conduction band (CB) of Bi2MoO6 and photogenerated holes (h(+)) in the valence band (VB) of g-C3N4 could combine with each other quickly, so that the e(-) in the CB of g-C3N4 and h(+) in the VB of Bi2MoO6 participated in reduction and oxidation reactions, respectively. Also, this composite exhibited superior physicochemical stability. Hence, it could be applied in advanced wastewater treatment.