Formation of Au-Pt bimetallic nanoparticles in a two-layer SiO2 films doped with Au and Pt, respectively, through interlayer diffusion

Bimetallic Au-Pt nanoparticles have been generated inside a relatively porous SiO2 film matrix by a two-layer (2L) coating methodology. Two overlapping coating layers were deposited on glass substrates from Au- and Pt-doped inorganic-organic hybrid silica sols and air dried at 60 degrees C. The 2L coating assembly was then UV- and followed by heat-treated at 450 and 550 degrees C in air. UV-treatment decomposes AuCl(4)(-) and PtCl(6)(2-) ions in the respective layers and the subsequent heat treatment in air influences the diffusion of Au and Pt nanometals to each other to form bimetallic Au-Pt nanoparticles inside the silica matrix. A UV-visible study showed damping of Au-plasmon after heat treatments. GIXRD and TEM analyses reveal the formation of a partial Au/Pt solid solution with a small fraction of Pt ( approximately 16%), while the major fraction of Pt remains fused with the Au(Pt) solid solution.