Polydopamine enhances the photocatalytic performance of a BiOBr-loaded 3D-printed monolithic photoreactor by fused deposition modeling

Abstract

Further improvement in the performance of monolithic photoreactors is crucial for their practical applications. Herein, a BiOBr@PDA composite was prepared via the solvothermal method, and then, it was loaded onto a 3D-printed monolithic photoreactor under ambient conditions to form the 20D-BiOBr@PDA photocatalyst. Using rhodamine B (RhB) as a model pollutant, the photocatalytic activity of the prepared devices was systematically evaluated. Results revealed that tuning the amount of polydopamine (PDA) coating significantly influenced the photocatalytic performance. When 20 mL of a dopamine solution was employed, the resulting 20D-BiOBr@PDA exhibited the highest photocatalytic efficiency, achieving a 95.0% degradation of RhB within 1 h. Furthermore, selective degradation experiments were conducted using various pollutants, including cationic dyes (RhB and methylene blue (MB)), an anionic dye (methyl orange (MO)), and an antibiotic (tetracycline (TC)). The 20D-BiOBr@PDA photocatalyst demonstrated the most pronounced degradation toward RhB, while the degradation efficiencies for MB, MO, and TC reached 94.3%, 47.3%, and 55.0%, respectively, after 3 h. Reactive species trapping experiments identified superoxide radicals (·O²⁻) as the predominant reactive species responsible for RhB degradation. Moreover, cyclic stability tests indicated that after 10 continuous cycles, the degradation efficiency of 20D-BOB@PDA for RhB remained at 90.0% within 1 h, confirming its excellent reusability and stability. This new approach introduces conductive polymers to enhance the photocatalytic performance of monolithic photoreactors.