Fusion and alloying of (bi)metallic nanocrystals onto TiO₂ nanowires in the presence of surface grafted polymer brushes

In present paper, the fusion of metal nanocrystals on TiO₂ nanowires is studied and utilized to synthesize bimetallic nanoparticles on nanowires. Cationic polydimethyl aminoethyl methacrylate (PDMAEMA) brushes are grafted onto TiO₂ nanowires, and palladium nanocrystals are produced by polymer brush-bound PdCl₄^2- and subsequent in situ reduction with NaBH₄ in high density and low polydispersity. It is found that Pd nanocrystals of 2-3 nm starts to fuse even at 100 °C, but are apparently obstructed by the polymer brush matrix. Nanocrystal fusion speeds up instantly after polymer decomposition degradation at temperatures above 300 °C. By taking advantage of the polymer brush technique successive, templated uploading of different nanoparticles and fusion, Pd-Au bimetallic nanoparticles or alloys are formed on TiO₂ nanowires. The results provide a novel method towards TiO₂ nanowire supported (bi)metallic nanoparticles and have hinted at practical uses for elucidating the catalytic behavior of the composites.