Surface-engineered Ag/TiO2/graphitic carbon nitride nanocomposites on cotton textiles for multifunctional photocatalytic, UV shielding, and antibacterial performance

• First time in situ synthesis of Ag/TiO 2 /g-C 3 N 4 nanocomposites on cotton fabric. • Ultrasound-assisted sol–gel synthesis at 70 °C enables multifunctional cotton. • Ag/TiO 2 /g-C 3 N 4 nanocomposite shows strong photocatalytic activity under solar light. • Modified cotton offers exceptional UV protection with a UV protection factor of 90. • Ag/TiO 2 /g-C 3 N 4 nanocomposite achieves complete bacterial reduction with no cytotoxicity. Ternary noble metal/semiconductor heterostructures are emerging as versatile platforms for multifunctional materials, but their integration into textiles remains limited. In this study, ultrasound-assisted sol–gel synthesis of Ag/TiO 2 /graphitic carbon nitride (gCN) nanocomposites directly on cotton fabric was developed. Two synthesis routes, i.e. in situ and ex situ were carried out at 20 °C and 70 °C to simultaneously achieve photocatalytic, UV protection, and antimicrobial properties. In situ synthesis at 70 °C resulted in the highest loading of TiO 2 and Ag nanoparticles (NPs), leading to superior multifunctional performance. The enhanced photocatalytic activity and photostability of the nanocomposite under solar light irradiation were attributed to a Type-II heterojunction between TiO 2 and gCN, the Schottky barrier formation at the Ag/TiO 2 interface, and the localised surface plasmon resonance of the Ag NPs. The synergistic effect of gCN and Ag NPs on UV-A absorption combined with TiO 2 -mediated UV-B shielding resulted in a UV protection factor of 90. The dual effect of Ag + and Ag 0 species provided complete bacterial inactivation of S. aureus and E. coli . The level of Ag NPs remained below the cytotoxic threshold, ensuring excellent cytocompatibility. These results establish Ag/TiO 2 /gCN nanocomposite-functionalised cotton as a promising candidate for advanced biomedical and technical textile applications.