Plate-on-plate structured Bi2MoO6/Bi2WO6 heterojunction with high-efficiently gradient charge transfer for decolorization of MB

• 2-D plate-on-plate Bi2MoO6/Bi2WO6 has been synthesized by a hydrothermal method.
• The Bi2MoO6/Bi2WO6 heterojunction provided charge separation at the interface.
• There is a gradient electron transfer in the Bi2MoO6/Bi2WO6 heterojunction.

To improve photocatalytic activity of semiconductor for increasing environmental pollution, heterojunction structured semiconductor composite has attracted a lot of attention due to direct enhancement in quantum efficiency. Despite numerous efforts, the current great challenge in materials science is to develop highly active photocatalysts. Here, 2-D plate-on-plate Bi2MoO6/Bi2WO6 heterojunction has been synthesized by one-pot hydrothermal method, which presented desirable combinations of their photocatalytic properties, much higher than the individual component. Surprisingly, the photocatalytic activity of the heterojunction could be remarkably enhanced after being annealed at 500 °C. Characterization results indicated that solid state reaction leads to the substitution of Mo or W into W or Mo sites at Bi2MoO6/Bi2WO6 interface, respectively, forming a novel Bi2WxMo1−xO6 component. The formed Bi2WxMo1−xO6 thin layer as the gangplank produced highly efficient gradient charge transfer due to matching band gap position. This unusual photocatalytic activity may be not only for the purpose of environmental remediation, but also for water splitting and photoelectrochemical cell.