Harnessing BiOI/V2O5 Nanocomposites: Advanced Bifunctional Catalysts for Visible-Light Driven Environmental Remediation and Antibacterial Activity

Abstract

Efficient photocatalysts based on composite materials are essential for addressing environmental pollution and enhancing water purification. This study presents a novel BiOI/V₂O₅ nanocomposite (BVNC) with a flower-like layered structure, synthesized via a low-temperature solvothermal process followed by high-pressure annealing for visible light (VL)-driven dye degradation and antibacterial activities. Compared to individual BiOI nanoparticles (BOINP) and V₂O₅ nanoparticles (VONP), under VL, the BVNC demonstrated significantly enhanced photocatalytic and antibacterial activity. The best-performing BVNC achieved a remarkable methylene blue degradation efficiency of 95.7% within 140 min, with a rate constant value 439% and 430% of those of BOINP and VONP, respectively. Additionally, BVNC exhibited high photocatalytic efficiencies for rhodamine 6G (94.0%), methyl orange (90.4%), and bisphenol A (69.5%) over 160 min, highlighting the superior performance of the composite materials for cationic and anionic dyes. Furthermore, BVNC established outstanding antibacterial capability against Staphylococcus aureus and Escherichia coli, demonstrating zones of inhibition of 12.24 and 11.62 mm, respectively. The improved catalytic and antibacterial capability is ascribed to the presence of a robust p-n heterojunction between BOINP and VONP, which broadens the photo-absorption range, reduces bandgap energy, and facilitates the significant separation of excitons and faster release of reactive oxygen species.

Keywords: BiOI/V2O5 composite; antibacterial activity; p-n heterojunction; visible-light-driven photocatalysts; wastewater treatment.

Figure 1

FE-SEM images of various nanoparticles and nanocomposites: (a) flower-like BOINP, (b) as-synthesized nanocomposite BVNC-1, (c) BVNC-2, and (d) BVNC-3. The inset in (a) displays the FE-SEM image of VONP.

Figure 2

Low (a) and high resolution (b) HR-TEM images of BVNC-1; lattice fringe (c), EDS for elemental color mapping (d) and EDS spectrum of the whole region of figure (e) of Bi (f), V (g), O (h), I (i), respectively, in BVNC-1.

Figure 3

HR-XRD peaks (a) of as-synthesized photocatalysts: (curve a) VONP, (curve b) BOINP, (curve c) BVNC-1, (curve d) BVNC-2, and (curve e) BVNC-3, and (b) magnified XRD patterns.

Figure 4

FT-IR spectra of VONP (curve a), BOINP (curve b), BVNC-1 (curve c), BVNC-2 (curve d), and BVNC-3 (curve e), respectively.

Figure 5

HP-XPS comparative spectra of (a) Bi-4f7/2 and 4f5/2 spectra of BVNC−1 composite (red line) and individual BOINP (black line), (b) V-2p spectra of the BVNC-1 composite (red line) and individual VONP (black line), (c) I 3d spectra of the BVNC-1 composite (red line) and individual BOINP (black line), and O 1s core−level spectrum of BVNC-1 (d), BVNC-2 (e), and BVNC-3 (f), respectively.

Figure 6

UV-Vis absorbance curves (a) and Tauc plots (b) illustrating the optical bandgap of BOINP, VONP, BVNC-1, BVNC-2, and BVNC-3, respectively.

Figure 7

Absorbance spectra of BVNC-1 (a), comparative photocatalytic performance (b), kinetic plot (c), and rate constant (d) for decomposition of MB in the presence of Blank, BOINP, VONP, BVNC-1, BNVC-2, and BVNC-3, respectively.

Figure 8

Recyclability tests of BVNC-1 (a), FT-IR spectra (b), and XPS survey plots from XPS of fresh and recycled BVNC-1 (c).

Scheme 1

Scheme of the energy band of (a) p-BiOI and n-V₂O₅ before contact, and (b) the formation of the p-n junction of p-BiOI to n-V₂O₅ under VL illumination.

Figure 9

Digital photograph of antibacterial performance of nanocomposites and nanoparticles against S. aureus (a) and E. coli (b), and their corresponding zone of inhibition (c), respectively.

Scheme 2

Schematic representation of the synthesis of BVNC.