Photocatalytic performance of inverse-opal g-carbon nitride and bismuth oxide compositing microstructures.

The development of visible-light photocatalytic materials in porous morphology with suitable photon management is significant for energy utilization and environmental protection. g-C₃N₄ and Bi₂O₃ are both typical visible-light semiconductor photocatalysts and their inverse-opal structures could provide larger surface area. Meanwhile, the fabrication of heterojunction composites is conducive to suppress the recombination of photo-generated carriers and enhance the photocatalytic performance. In this work, g-C₃N₄ inverse opals on the basis of TiO₂ or TiO₂/SiO₂ framework and Bi₂O₃ inverse opals were successfully synthesized by a simple sol-gel method. The photocatalytic performance gets improved with the introduction of g-C₃N₄ in inverse opals, and the removal of SiO₂ in SiO₂/TiO₂ framework provides additional mesoporous morphologies which further advances the light harvesting efficiency. The photocurrent densities of the inverse-opal structures are all higher than the corresponding films. The photonic band gap position originated from the periodicity of inverse opals was modulated by using colloidal crystals template in different diameters. Better photochemical characteristics are achieved when the absorption peak of Bi₂O₃ is coincident with the high-frequency photonic band edge of inverse opals. The heterostructures consisting of g-C₃N₄ inverse opals and Bi₂O₃ inverse opals were fabricated and stronger optical absorption and higher transient photocurrent responses are presented compared with both individual inverse-opal structures.. [ABSTRACT FROM AUTHOR]