Engineering the S-scheme heterojunction between NiFeAl - LDH and BiOCOOH nanoflower by constructing an interfacial electric field for efficient degradation of levofloxacin under visible light

Abstract

The antibiotic levofloxacin (LVF), utilized across the world during the COVID-19 pandemic, presents a notable concern in environmental safety owing to its deposition in water bodies. This work reports the engineering of S-scheme heterojunction, NiFeAl LDH coupled with BiOCOOH nanoflower by constructing an interfacial electric field for efficient degradation of LVF under visible light. The scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis reveal the uniform decoration of NiFeAl LDH flakes over flowers like BiOCOOH and the high crystallinity is confirmed with SAED pattern distribution. The construction of an interfacial electric field was confirmed by X-ray photoelectron microscope (XPS) analysis. The X-ray diffraction (XRD), XPS, and Raman spectroscopy studies were conducted to confirm the purity and chemical bonding nature of the BiOCOOH-NiFeAl LDH nanocatalyst (NFB NCs). The band gap of materials was calculated to be 3.38 and 2.03 eV for BiOCOOH and NiFeAl LDH respectively. The NFB NCs showed remarkable performance of 95.2 % than its pristine BiOCOOH (35.4 %) and NiFeAl LDH (18 %). ESR and scavenging studies identified the major involvement of •OH, O2•- and h+ in the process. The intermediates formed during the degradation were examined by using GC–MS and a possible degradation pathway was proposed. Furthermore, the toxicity analysis using the ECOSAR program demonstrates NFB NCs safety level for extensive wastewater treatment. The stability of the NCs over six cycles and magnetic removal properties showcased their potential for large-scale wastewater treatment applications. This comprehensive study highlights the importance of LDH in advancing photocatalytic materials for environmental remediation and paves a way for manufacturing innovation.