“Enhancing wastewater treatment: DFT and experimental insights into ZnO-implanted TiO2 Z-scheme photocatalyst mediated via Smilax aspera"

Abstract

This comprehensive study aimed to optimize the performance of photogenerated carriers in catalytic and optoelectronic systems by effectively separating electron-hole pairs. Green-synthesized TiO₂ nanoparticles (average size ∼21 nm) and zinc acetate (99.5 % purity), augmented with eco-friendly integration of the plant Smilax aspera, resulted in a tailored hollow direct Z-scheme photocatalyst, ZnO–TiO₂, with adjustable ZnO loading ranging from 0.5 wt% to 5 wt%. Characterization techniques such as X-ray Diffraction, Fourier Transform Infrared Spectroscopy, Ultraviolet–Visible Spectroscopy, Transmission Electron Microscopy, Thermogravimetric Analysis and Energy-Dispersive X-ray Spectroscopy provided detailed insights into the atomic and electronic properties of the material. The analysis revealed the coexistence of anatase TiO₂ and wurtzite ZnO phases, each exhibiting distinct electronic band structures within the composite. Density functional theory calculated band gap values of 2.02 eV for TiO₂ and 2.89 eV for ZnO–TiO₂ corroborated the experimental results, offering a deeper understanding of electronic transitions within the heterojunction. The ZnO–TiO₂ composite showed significant photocatalytic efficacy in degrading Methylene Blue (98 % in 15 min) and Rose Bengal (79.69 % in 40 min) under UV light. It also exhibited antifungal potential against Aspergillus niger and Candida albicans, with inhibition zones of 28.0 ± 0.12 mm and 30.23 ± 0.68 mm, respectively. This research provides valuable insights into the eco-friendly, multifunctional applications of the ZnO–TiO₂ Z-scheme photocatalyst. This research thus provides valuable insights into the multifaceted applications of this synergistic, eco-friendly heterojunction photocatalyst in environmental remediation and its role as an effective antifungal agent.