A plasmonic S-scheme Au/MIL-101(Fe)/BiOBr photocatalyst for efficient synchronous decontamination of Cr(VI) and norfloxacin antibiotic

Abstract

Present photocatalysts for the synchronous cleanup of pharmaceuticals and heavy metals have several drawbacks, including inadequate reactive sites, inefficient electron–hole disassociation, and insufficient oxidation and reduction power. In this research, we sought to address these issues by using a facile solvothermal-photoreduction route to develop an innovative plasmonic S-scheme heterojunction, Au/MIL-101(Fe)/BiOBr. The screened-out Au/MIL-101(Fe)/BiOBr (AMB-2) works in a durable and high-performance manner for both Cr(VI) and norfloxacin (NOR) eradication under visible light, manifesting up to 53.3 and 2 times greater Cr(VI) and NOR abatement rates, respectively, than BiOBr. Remarkably, AMB-2's ability to remove Cr(VI) in a Cr(VI)-NOR co-existence system is appreciably better than in a sole-Cr(VI) environment; the synergy among Cr(VI), NOR, and AMB-2 results in the better utilization of photo-induced carriers, yielding a desirable capacity for decontaminating Cr(VI) and NOR synchronously. The integration of MOF-based S-scheme heterojunctions and a plasmonic effect contributes to markedly reinforced photocatalytic ability by increasing the number of active sites, augmenting the visible-light absorbance, boosting the efficient disassociation and redistribution of powerful photo-carriers, and elevating the generation of reactive substances. We provide details of the photocatalytic mechanism, NOR decomposition process, and bio-toxicity of the intermediates. This synergistic strategy of modifying S-scheme heterojunctions with a noble metal opens new horizons for devising excellent MOF-based photosystems with a plasmonic effect for environment purification.

Keywords

• Au/MIL-101(Fe)/BiOBr
• Metal–organic framework (MOF)
• Plasmonic effect
• S-scheme
• Cr(VI) removal
• Antibiotic degradation