Dual S-scheme heterojunction ZnO–V2O5–WO3 nanocomposite with enhanced photocatalytic and antimicrobial activity

Abstract

In this work, tri-phase direct dual S-scheme ZnO–V2O5–WO3 heterostructured nanocomposite and pure ZnO, V2O5, and WO3 nanoparticles were synthesized by using a facile co-precipitation approach to investigate antibacterial and photocatalytic characteristics of the grown nanocomposite. The physical properties of as-synthesized products were examined by employing characterization techniques such as Scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman, Fourier transform infrared spectroscopy (FTIR), and UV–vis spectroscopy. The XRD results confirmed the formation of pristine ZnO, V2O5, WO3 nanoparticles and the existence of diffraction peaks related to hexagonal phase ZnO, orthorhombic V2O5, and monoclinic phase of WO3 in ZnO–V2O5–WO3 nanocomposite. The variation in structural parameters was studied by SSP, Scherrer plot, and W–H models. The energy bandgap of nanocomposite (2.63 eV) was calculated from UV–vis spectroscopy, which indicated the usability as a photocatalyst under direct sunlight. FTIR and Raman's spectra also supported the formation of the ZnO–V2O5–WO3 nanocomposite. Spherical and roughly hexagonal morphology were seen in SEM images. EDX analysis has confirmed the existence of Zn, V, W, and O in the nanocomposite. The antibacterial test against Klebsiella pneumonia, Staphylococcus aureus, Proteus Vulgaris, and Pseudomonas aeruginosa bacteria showed higher activity. The photocatalytic performance of the ZnO–V2O5–WO3 nanocomposite (99.8%) was the highest against methylene blue (MB) as compared to pure ZnO (78.8%), V2O5 (85.8%), and WO3 (80.0%) under natural sunlight. The degradation efficiency of ZnO–V2O5–WO3 against cresol red (CR), rhodamine-B (RhB), methyl orange (MO), safranin-O (SO), and methyl red (MR) dyes was 67.0%, 86.6%, 98.0%, 76.8%, and 99.0%, respectively, under direct sunlight in 80 min. Different schematic models are designed to illustrate the photocatalytic reaction mechanism, whereas the separation of charge carriers and enhanced photocatalytic performance can be efficiently explained by S-scheme.