This research aimed to explore the suitability of using a novel g-C3N4–Ag–Cu–Ni nanocomposite for the simultaneous degradation of pyrene in wastewater. The g-C3N4 phase was successfully fabricated and helped stabilize Ag–Cu–Ni particles. The nanocomposite demonstrated excellent pyrene degradation performance under various conditions, with degradation increasing as the dosage increased. The results indicate that the material is promising for water purification, especially for simultaneous photocatalytic and antimicrobial treatment of contaminated water. © 2023 Elsevier B.V., All rights reserved.