Boosting photocatalytic and antibacterial properties through Schottky heterojunction of N-TiO2/Ag reverse composite under visible light

This study investigates the functionalities of nitrogen-doped titanium dioxide (N-TiO2) with embedded dispersed silver nanoparticles (AgNPs) composites as visible-light photocatalysts and antibacterial agents. Compared with most of the silver-titania photocatalysts, the composite has a reverse concept, where the silver nanoparticles are embedded in N-TiO2 layers and act as an internal Schottky junction to limit the charge carriers' recombination. Raman spectroscopy, SSA, UV-Vis DRS, PZC, SEM-EDX, FTIR-ATR, and X-ray diffraction (XRD) confirmed that nitrogen addition through urea in the synthesis successfully narrows the TiO2 bandgap, thereby enhancing its absorption of visible light and the inclusion of AgNPs, generating internal Schottky heterojunctions that enhance charge separation and electron transfer, optimizing photocatalytic performance. The optimized N(0.43)-TiO2/ AgNPs composite achieves 86.6 % mineralization of the model pollutant Patent Blue V under visible light, with hydroxyl radicals and positive holes responsible for degradation. Beyond photocatalytic activity, the composite exhibits strong antibacterial efficacy, reducing Escherichia coli (E. coli) and Staphylococcus. Aureus (S. aureus) populations by 95.62 +/- 0.47 and 90.74 +/- 0.63 % inhibition, respectively, at a concentration of 1000 mu g mL- 1. Finally, an energy band diagram is schematized. The composite demonstrates excellent stability, emphasizing its potential for practical applications in wastewater treatment and infection control.