Fabrication of 2D/2D g-C3N4/Au/Bi2WO6 Z-scheme photocatalyst with enhanced visible-light-driven photocatalytic activity

A series of novel 2D/2D Z-scheme visible-light-driven g-C3N4/Au/Bi2WO6 (CN/Au/BWO) photocatalysts were fabricated via a photoreduction and hydrothermal reaction process. The microscopic mechanisms of interface interaction, charge transfer and separation, as well as the influence on the photocatalytic activity of CN/Au/BWO composite were systematic investigated. The photocatalytic performance of CN/Au/BWO photocatalysts was evaluated by the photodegradation of Rhodamine B under visible-light illumination. The results showed that CN/Au(1)/BWO displayed the optimum photocatalytic activity, which was 1.48 times and 1.62 times as that of Bi2WO6 nanosheets and g-C3N4, respectively. The improved photocatalytic activity of CN/Au/BWO could be mainly attributed to the construction of 2D/2D Z-scheme architectures, which not only provided abundant active sites but also effectively improved the separation rate of photogenerated carriers. It was noted that Au nano-particles acted as a redox mediator in the Z-scheme heterostructure between Bi2WO6 and g-C3N4 to promote the transmission and separation of photo-generated electrons and holes in the middle of Bi2WO6 and g-C3N4. A possible photocatalytic reaction mechanism of photocatalytic RhB degradation over CN/Au/BWO was tentatively proposed through active species trapping experiments. In summary, the current study could provide a new insight for designing effective 2D/2D Z-scheme photocatalysts to guide the further improvement of their photocatalytic activity.