Enhanced photocathodic antifouling/antibacterial properties of polyaniline–Ag–N-doped TiO2 coatings

Currently, there is tremendous interest in the development of surface coatings for outdoor applications that are self-cleaning with strong antibacterial properties. Herein, aniline was polymerized in situ with silver–N-doped TiO2 composites to fabricate PANI–Ag–N–TiO2 nanocomposites, which were then mixed with an acrylic resin to form coatings on type 316L stainless steel. Under UV–Vis light illumination, the PANI–Ag–N–TiO2 coatings delivered a stable photocathodic potential of − 0.79 V, a much larger negative potential than was realized using PANI–N–TiO2 (− 0.55 V) or PANI–TiO2 (− 0.40 V) coatings. The addition of Ag nanoparticles thus greatly enhanced the photo-cathodic response. Antimicrobial experiments demonstrated that the PANI–Ag–N–TiO2 coating offers good antibacterial activity (> 95% inhibition) against E. coli under UV–Vis light irradiation for 30 min, due to the generation of hydrogen peroxide or other reactive oxygen species capable of damaging the membrane of E. coli cells. Results suggest that PANI–Ag–N–TiO2 composite coatings offer good antifouling performance in marine environments.