Synergistic Mn/N/F Tri-Doped TiO_۲ Nanoparticles: Bandgap Narrowing and Defect Passivation for Solar-Driven Pollutant Degradation

The persistent challenge of organic pollutant remediation demands efficient solar-driven photocatalysts. Titanium dioxide (TiO۲), though widely used, suffers from a wide bandgap (~۳.۲ eV), limiting activity to UV light and rapid charge recombination. This study introduces a tri-doped TiO۲ system (Mn/N/F- TiO۲) to overcome these limitations. Nitrogen doping narrows the bandgap via localized states above the valence band, enabling visible-light absorption (۴۰۰–۶۵۰ nm). Manganese introduces mid-gap Mn³⁺/Mn²⁺ redox states, suppressing charge recombination by trapping electrons. Fluorine passivates surface defects, stabilizes the anatase lattice, and enhances hydrophilicity for improved charge transfer. Characterization via XRD, XPS, BET, and DFT confirms homogeneous dopant incorporation, reduced crystallite size (۱۴.۳ nm), and optimized mesoporosity (surface area = ۱۱۸ m۲/g, pore volume = ۰.۳۵ cm۳/g). The tri-doped catalyst achieves ۹۸% methylene blue degradation under visible light in ۱۲۰ min—surpassing single/dual-doped counterparts. The enhanced performance stems from synergistic effects: extended carrier lifetimes and efficient charge separation. By balancing bandgap engineering, defect passivation, and structural stability, this work establishes a multi-dopant design framework for TiO۲ photocatalysts. The findings advance scalable solar-driven technologies, offering solutions for wastewater treatment, self-cleaning surfaces, and sustainable photocatalysis, bridging the gap between lab-scale innovation and practical environmental applications.

کلیدواژه ها:

Photocatalysis ، TiO۲ ، Co-doping ، density functional theory ، Bandgap Narrowing