Room Temperature Synthesis of Visible Light Active PANI/BiOBr Z-Scheme Heterojunction for the Photocatalytic Degradation of Rhodamine B

Photocatalytic degradation using freely available sun light is one of the crucial approaches in remediation of persistent organic pollutants, such as rhodamine B (RhB). Developing effective photocatalysts is one of the key challenges in meeting such sustainable development goals. In this study, a series of binary composite photocatalysts of bismuth oxybromide (BiOBr) with varying amounts of polyaniline (PANI) were synthesized at room temperature. The nanocomposite, with 9 wt % of PANI (PB-70) displayed enhanced photocatalytic performance for the degradation of RhB dye when compared to bare PANI and BiOBr, under visible light. The degradation of 20 ppm RhB reached 100% in about 30 min using PB-70 as the photocatalyst. Moreover, complete mineralization of RhB also could be achieved using PB-70. Predominant involvement of superoxide ion (•O₂^─) radicals along with lower contributions from holes (h⁺) and hydroxyl (•OH) radicals was evident from the scavenger studies. Enhanced photophysical properties of PB-70 were confirmed, when compared to PANI and BiOBr. Formation of a Z-scheme heterojunction between PANI and BiOBr in the PB-70 was thus, found to be the reason for the enhanced photocatalytic activity.