DecatungstateAu nanoparticlesPhoto-catalytic oxidationHydrocarbonsMolecular oxygenHETEROPOLY ACID CATALYSTSOLVENT-FREE OXIDATIONSELECTIVE OXIDATIONVISIBLE-LIGHTPHOTOCATALYTIC ACTIVITYGOLD NANOPARTICLESELECTRON-TRANSFEREXCITED-STATEPLASMONIC PHOTOCATALYSTSETHYLBENZENE OXIDATION