Under ambient light illumination, silver nanoparticles can be synthesized by a triblock copolymer induced reduction of [Ag(NH3)(2)](+) ions in ethanol. Conventional chemical reducing agents, thermal treatment, and radiation sources are no longer necessary in this novel approach. A possible mechanism was proposed to explain the formation and stabilization of silver nanoparticles based on UV-vis absorption spectra and transmission electron microscopy results. This novel ambient light route has been successfully applied to deposit silver nanoclusters on TiO2. Silver nanoclusters of about 2 nm in size were found to strongly anchor to the TiO2 nanoparticles with high dispersion. The resulting silver-coated TiO2 material with optimal silver loading showed enhanced photocatalytic and bactericidal activities compared to the uncoated TiO2. The reasons for the enhancements of the activities were discussed.