In2S3-decorated TiO2 nanotubes with a Type-II heterojunction for enhanced photoelectrochemical cathodic protection of 316L stainless steel

In this study, TiO 2 nanotubes decorated with In 2 S 3 films were fabricated by anodic oxidation followed by hydrothermal deposition. Under optimized conditions (2 mmol precursor, 12 h), the TiO 2 /In 2 S 3 photoanode delivered a photocurrent density of 3 μA cm −2 and a photovoltage drop of 400 mV under AM 1.5 G irradiation, demonstrating enhanced photoelectrochemical cathodic protection. In addition, the composite exhibited strong photocatalytic antimicrobial activity. Plate count assays showed a dose-dependent bactericidal effect, achieving bacterial elimination at 2.5 mg/mL under illumination, while exhibiting negligible dark toxicity. Mechanistic analysis indicated that the type-II heterojunction promotes charge carrier separation and inhibits recombination, thereby improving both photoelectrochemical cathodic protection and antibacterial performance. • A photocurrent density of 3 μA cm −2 and OCP shift of 400 mV vs.Ag/AgCl were achieved under AM 1.5 G. • Complete bacterial elimination was realized at 2.5 mg/mL under illumination. • Type-II heterojunction enhanced charge separation and suppressed recombination.