Facile synthesis of bimetallic nanoparticles by femtosecond laser irradiation method

Abstract

Bimetallic Pt–Au and Fe–Pt nanoparticles are successfully fabricated by high-intensity laser irradiation of aqueous solution without any chemical reducing agent. The mechanism of the formation of bimetallic nanoalloys by laser irradiation of the solution without using any reducing agent was mainly attributed to the optically induced decomposition of water molecule. When an intense femtosecond laser field is focused in an aqueous solution containing metal ions, the free electrons will be produced by the dissociation of water molecules, these free electrons and hydrogen radicals contained in the plasma might be caught by H+ or OH− ions to form the bubbles of H2 and O2 gases or they can be trapped by metal ions, resulting in the formation of metal atoms during the femtosecond laser irradiation process. The average size of the bimetallic nanoparticles increases with irradiation time. This technique is simple and ‘green’ process without using any chemicals except for metal salt and dispersing agent.