Ag@AgxH3-xPW12O40 (Ag@AgHPW) nanoparticles (NPs), a new visible-light driven plasmonic photocatalyst, are prepared by a green photoreduction strategy without the addition of any surfactant. They show strong absorption in the visible region because of the localized surface plasmon resonance (LSPR) of Ag NPs. This plasmonic photocatalyst shows a high activity and stability for the degradation of methyl blue (MB) under visible light irradiation, which could be attributed to the highly synergy of photoexcited AgxH3-xPW12O40 (AgHPW) and plasmon-excited Ag NPs and the confinement effects at interfaces between polyoxometalates (P0Ms) and silver. POM anions have redox ability and high photocatalytic activity, whereas Ag NPs could effectively accelerate the separation of electrons and holes, both of which contribute to their high activity. (C) 2013 Elsevier Ltd. All rights reserved.