Doped photocatalyst immobilization on tubular surface: continuous photocatalysis of pharma drugs under visible light

Abstract

This study presents the fabrication and characterization of nitrogen-doped TiO₂ (N–TiO₂) thin films deposited on cylindrical quartz tubes for photocatalytic applications. A binder-free modified dip-coating technique is developed to uniformly immobilize the TiO₂ films, using a sol–gel process with amine-based precursors to control nitrogen doping levels. Thermal annealing ensured strong adhesion of the films to the substrate. Characterization by XRD, UV-vis spectroscopy, FTIR, and XPS confirmed nitrogen incorporation, phase formation, and modifications in band gap and surface chemistry. XPS further detailed the elemental composition and electronic states, highlighting the role of nitrogen in enhancing photocatalytic properties. The visible-light-driven photocatalytic performance is evaluated through the degradation of ciprofloxacin in aqueous medium, with more than 85% degradation efficiency. The improved activity is attributed to effective nitrogen doping and robust film adhesion. This scalable method offers a promising route to producing durable, high-performance photocatalysts for sustainable water treatment technologies.