Comparative Study of Hydrothermal and Sonochemical Preparation of Cu and Ag Codoped ZnO/Graphene Nanocomposites for Enhanced Catalytic and Inactivation of Pathogens

Developing high‐performing photocatalysts and composites generate synergetic effects in modern photocatalysis. Zinc oxide (ZnO) is a promising photocatalyst; however, its wide bandgap and high charge carrier recombination rate significantly limit its visible‐light activity and overall photocatalytic efficiency. To overcome these challenges, this study focuses on the synthesis of Cu–Ag codoped ZnO/graphene nanocomposites using both hydrothermal and sonochemical methods, aiming to regulate the interfacial interaction and enhance charge separation. The hydrothermally synthesized (CAZ/Gr) H composite exhibited a lower bandgap, improved carrier transfer efficiency, and stronger Zn–O–C interfacial bonding compared to the sonochemically prepared (CAZ/Gr) S sample. Density functional theory (DFT) calculations confirmed the reduced work function and enhanced electron mobility in the hydrothermal system. Under natural sunlight, the (CAZ/Gr) H composite demonstrated superior photocatalytic degradation of organic dyes and excellent antibacterial activity against E. coli and S. aureus . These findings highlight the effectiveness of interface‐regulated, green‐synthesized ZnO‐based nanocomposites in addressing the fundamental limitations of traditional ZnO photocatalysts.