Composition production methods are provided that can include providing PdO nanoparticles on a nitrogen-doped titanium oxide surface to form a catalytic mixture. Catalytic compositions and/or bactericides are provided that can include a substrate supporting Ti, O, N, and Pd. Water purification methods are provided that can include exposing an aqueous solution to a composition comprising at least a substrate supporting Ti, O, N, and Pd. Photocatalytic methods are provided that can include: providing a composition comprising one or both of Ti and Pd; exposing the composition to visible radiation to activate the composition; and in the substantial absence of the visible radiation, contacting the composition with an aqueous solution to purify the aqueous solution. Embodiments of the disclosure provide visible light photocatalysts that can demonstrate faster photocatalytic disinfection rates on Escherichia coli (E. coli) under visible light illumination as compared to nitrogen-doped titanium oxide (TiON), as well as catalytic activity after visible light illumination is substantially removed.
GOVERNMENT RIGHTS STATEMENT
 This invention was made with Government support by the Center of Advanced Materials for the Purification of Water with Systems, National Science Foundation, under Agreement Number CTS-0120978; Grant Number DEFG02-91-ER45439 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.