One of the potential treatments for bacterial wound infections is photodynamic therapy. WO3-x semiconductor materials can generate reactive oxygen species when exposed to light, which can inactivate bacteria. In this work, we improved their photocatalytic performance by doping WO3-x with Cu. The wound dressing was prepared by loading Cu-WO3-x into a highly biocompatible chitosan sponge. The composite sponge dressing showed significant inactivation of Escherichia coli and Staphylococcus aureus, and in vitro toxicity assays on L929 cells demonstrated the biosafety of the dressing. Through in vivo wound healing trials, composite sponge dressings have been shown to accelerate wound healing, and this composite chitosan sponge can be possibly used for photodynamic therapy of bacterial wound infections.