Ag/Cu modified K4Nb6O17 thin film, a novel type of photocatalyst for photocatalytic inactivation of Escherichia coli under visible light irradiation was developed. The effects of loading method of Cu species on the characteristics of Ag-Cu nanocomposites and photocatalytic antibacterial activity were studied. Samples were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectroscopy (UV-Vis). Irrespective of the preparation method, loading Ag, Cu and Ag-Cu composite as cocatalyst led to an increase in antibacterial activity as compared to bare K4Nb6O17. In comparison with conventional impregnation method, well dispersed Ag-Cu nanocomposites were obtained on the K4Nb6O17 surface by a sodium borohydride reduction method in the presence PVP. In this case, markedly improvement of photocatalytic activity was observed. The significant enhancement was ascribed to the high efficiency of electron hole pair separation related to the Ag-Cu nanocomposite on K4Nb6O17 surface and the synergistic effects of coexisting Ag and Cu ions on antibacterial activity. (C) 2012 Elsevier B.V. All rights reserved.