Abstract
Wide spectral responsive photocatalysts with improved charge separation and transfer capacity have attracted researchers for various photo-oxidative and reductive applications. This work reports Vis-NIR active photocatalyst Ag@Bi4O5I2/SPION@calcium alginate (here in designated as ABSA) prepared by hydrothermal impregnation for high performance degradation of azithromycin (AZY) and selective reduction of NO3- into N-2. The composite catalyst ABSA shows 98.4% AZY degradation in 90 min with visible light. Surprisingly, the apparent rate constant for ABSA catalyst (0.08321 min(-1)) is similar to 8 times higher than bare Bi4O5I2. The photocatalyst is capable of selectively reducing NO3- into N-2 with formic acid at a wide range of pH especially in acidic conditions with similar to 100% photo-reduction and 97.6% N-2 selectivity. The high performance is manifested in the excellent photoreduction and oxidative capabilities under UV, visible, NIR and sunlight. SPIONs and Ag improve the visible activity, I-3(-)/I- redox mediates better charge flow and Ag provides "hot electrons" via SPR effect. O-center dot(2-) radicals are the active species during AZY degradation as confirmed by ESR probe. (CO3-)-C-center dot plays immensely important role in selective NO3- reduction into N-2. This work reports a relatively simple photocatalytic system with more bio-benevolence utilizing Bi4O5I2 and Calg and modifying with Fe3O4 and Ag as dopants for a wide spectral photo-redox capability. The hybrid wide spectrum responsive material integrates environmental friendliness, robust structure, full recycling and stability with sturdy improvement in photocatalytic efficiency.