Interfacial Engineering of Nitrogen-Doped Titanium Dioxide in Hydrogel–PDMS for Photocatalytic Antimicrobial Coatings

Overview

The increasing prevalence of antibiotic-resistant infections has necessitated the development of passive, self-cleaning antimicrobial materials. Titanium dioxide (TiO2) is a widely studied photocatalyst capable of generating reactive oxygen species (ROS) that inhibit bacterial growth. However, its activation is largely confined to ultraviolet (UV) light, limiting practical efficacy. This project aims to shift the photocatalytic response of TiO2 into the visible-light spectrum through physical nitrogen doping to enhance antimicrobial performance. Nitrogen-doped TiO2 (N–TiO2) nanoparticles were synthesized via thermal decomposition of varying urea masses (0.01g–0.50g) with anatase TiO2 (0.20g) at 350°C for one hour. Each powder was dispersed at 1 w/v% in 70% ethanol and characterized using UV–Vis spectroscopy. The doped composites were then incorporated at 2 wt% into 1:1 hydrogel–PDMS films and evaluated against Bacillus subtilis at 25°C for 72 hours under visible-light exposure. The optimal film was further tested for reusability and across varyinging coating thicknesses. Films containing 0.15g of urea exhibited optimal efficacy, reducing bacterial growth by approximately 84% relative to untreated controls and by ~80% compared to the undoped TiO2 films. This formulation also demonstrated the highest absorbance at 420 nm. Higher dopant concentrations resulted in diminished antimicrobial activity. Repeated trials confirmed that antibacterial efficacy was retained for up to seven iterations, and thickness optimization at 0.05cm increased bacterial inhibition to 98%. These results demonstrate that nitrogen doping activates TiO₂-mediated ROS generation under visible light and highlight such composites as promising low-cost antimicrobial coatings.

Competition history

• CSEF 2026 Chemistry (Senior Division) · Entry S-05-08

Related projects

Closest projects by meaning, across every fair and year in the corpus.

Browse more like this

• All Chemistry projects
• CSEF Chemistry projects
• Every CSEF 2026 project