Synthesis of silver nanoparticles (Ag NPs) with state-of-the-art chemical or photo-reduction methods generally takes several steps and requires both reducing agents and stabilizers to obtain NPs with narrow size distribution.Herein,we report a novel method to synthesize Ag NPs rapidly in one step,achieving typical particle sizes in the range from 5 to 15 nm.The synthesis steps only involve three chemicals without any reducing agent:AgNO3 as precursor,polyvinylpyrrolidone (PVP) as stabilizer,and AgCl as photocatalyst.The Ag NPs were supported on carbon and showed excellent performance in thermal catalytic pnitrophenol reduction and nitrobenzene hydrogenation,and as electrocatalyst for the oxygen reduction reaction.