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-TiO 2 ) 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-TiO 2 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 TiO 2 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)-TiO 2 /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 S taphylococcus . Aureus ( S. aureus ) populations by 95.62 ± 0.47 and 90.74 ± 0.63 % inhibition, respectively, at a concentration of 1000 μg 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. • Novel composite material embedding commercial 30-50 nm Ag NPs in N-doped TiO2. • The composite photocatalyst has a reverse concept, in which the silver nanoparticles are inside the doped photocatalyst. • The composite was thoroughly characterized, showing silver present in low amount at the nitrogen-doped titania surface. • Successful application for both PBV photocatalytic degradation and antibacterial activity under visible light.