Oriented immobilization of Au nanoparticles on C@P4VP core–shell microspheres and their catalytic performance

Abstract

Core–shell C@poly(4-vinylpyridine) (C@P4VP) microspheres immobilized with small and uniform Au nanoparticles were designed and fabricated. Firstly, the C@P4VP support was obtained by coating a poly(4-vinylpyridine) shell on the carbon spheres through the hydrogen-bond interaction between –COOH of carbon spheres and pyridine of 4-vinylpyridine. Then Au nanoparticles were synthesized by in situ adsorption and reduction of HAuCl₄ in the P4VP chains of the C@P4VP microspheres. Carbon spheres can serve as hard templates and prevent the polymeric P4VP shell from excessive deformation. The coordination between cross-linked networks of P4VP chains and the embedded Au nanoparticles effectively inhibit the aggregation and leaching of noble metal nanoparticles from the support. The resulting C@P4VP–Au microspheres showed excellent catalytic performance and high cyclic stability in the aqueous reduction of 4-nitrophenol by NaBH₄. Moreover, optimal activities were observed for the P4VP shell with a low cross-linked degree and a reaction system with a low pH value.