Synthesis and assembly of catalytically active platinum-doped polymer nanocomposites at the liquid/liquid interface

摘要

Platinum nanoparticle-doped polymer foam-like thin films were prepared via a synthesis and assembly process at the liquid/liquid interface of a chloroform solution of poly(2-vinylpyridine) and an aqueous solution of chloroplatinic acid hydrate and a subsequent UV-light irradiation process. Transmission electron microscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy investigations indicated that the foam-like thin films formed at the interface were composed of polymer molecules, and Pt(II) and Pt(IV) ions. Platinum nanoparticles with average diameter of 2.70±0.35nm appeared after UV-light irradiation, which were embedded in and adsorbed on the walls of the foams. The formation of the composite nanostructures at the interface was attributed to self-assembly of the polymer molecules at the liquid/liquid interface, reduction of PtCl_6~(2-), and interaction between PtCl_6~(2-)/intermediate PtCl_4~(2-) ions and the protonated pyridine groups. The catalytic activity of the composite film for the reduction of methylene blue by potassium borohydride in aqueous solutions was evaluated. The apparent rate constant decreased gradually with increasing the number of runs due to the partially leaching of Pt nanoparticles and became stable after the fifth cycle, indicating that the composite film can be used as an effective, stable and reusable catalyst.