Ultrasonically dispersed ultrathin g-C₃N₄ nanosheet/BaBi₂Nb₂O₉ heterojunction photocatalysts for efficient photocatalytic degradation of organic pollutant

Here, we present new graphite-like C₃N₄ (g-C₃N₄)/BaBi₂Nb₂O₉ composites with remarkable photocatalytic activities under solar light irradiation that were prepared by a facile ultrasonic dispersion method. A heterojunction was formed with Aurivillius type BaBi₂Nb₂O₉ particles and ultrathin g-C₃N₄ nanosheets, and this composite material was characterized by using several techniques. The ultrathin g-C₃N₄ nanosheets promoted extensive contact in the heterojunction, as observed by morphological analyses. Moreover, the as-synthesized ultrathin g-C₃N₄ nanosheets are highly porous with a specific surface area of 141 m²/g. The BaBi₂Nb₂O₉ particles strongly absorb ultraviolet (UV) light whereas, by comparison, g-C₃N₄ absorbs visible light more effectively, as established by diffuse reflectance spectroscopy DRS analysis. These properties substantially improved the capacity of the as-fabricated g-C₃N₄/BaBi₂Nb₂O₉ heterojunction to photocatalytically degrade the organic dye Rhodamine B (RhB) under simulated solar light and 40 W UV–visible light irradiation, versus either of the separate components of the heterojunction. Specifically, an optimal composite with approximately 30 wt% BaBi₂Nb₂O₉ content exhibits an apparent reaction rate 0.02056 min⁻¹ for RhB photodegradation under simulated solar light, which was nearly 1.5- and 4.3-fold higher than that of the pristine g-C₃N₄ and BaBi₂Nb₂O₉ photocatalysts, respectively. In addition, the same composite had an apparent reaction rate of 0.0155 min⁻¹ for RhB photodegradation under 40 W UV-Vis light irradiation, which was approximately 1.4- and 2.8-fold higher than the pristine components. These functionalities are also supported by photoluminescence spectroscopy analyses and photocurrent responses, which indicate a photosynergistic effect for the g-C₃N₄/BaBi₂Nb₂O₉ heterojunction that enhances photoinduced interfacial charge transfer.