Direct Dual Z-Scheme Bi2WO6/GQDs/WO3 Inverse Opals for Enhanced Photocatalytic Activities under Visible Light

A direct dual Z-scheme photocatalyst is facilely fabricated by anchoring graphene quantum dots uniformly onto the framework of one-pot-synthesized Bi2WO6/WO3 inverse opals via electrostatic attraction. A series of Bi2WO6/GQDs/WO3 inverse opals (BGW IOs) with different Bi2WO6 contents are synthesized and evaluated for their photocatalytic activities. The results indicate that the novel dual Z-scheme heterostructure shows excellent photocatalytic performance in phenol degradation and mineralization compared with pure WO3 IO under visible light illumination. Meanwhile, 0.5Bi2WO6/GQDs/WO3 IO (0.5BGW IO) exhibits optimal photocatalytic efficiency for phenol degradation, which is 2.8 times higher than that of individual WO3 IO within 120 min. The excellent photocatalytic activities of BGW IO heterojunctions are attributed to the synergistic effect of the increased light harvesting due to the slow photon effect of Bi/W IO and the inhibited recombination of photoexcited carriers based on a direct dual Z-scheme photocatalytic mechanism. The active species capture experiment and electron spin-resonance (ESR) analysis demonstrate that •OH, •O2–, and h+ are generated in the BGW IO photocatalytic system. What is more, the BGW IO photocatalyst performs high reusability.