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

Abstract

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.