The effect of poly(vinylpyrrolidone) (PVP) on the Au catalyzed reduction of p-nitrophenol: The fundamental role of NaBH4.

Abstract

The effect of polymeric ligands, like poly(vinylpyrrolidone) (PVP), on the reduction of p-nitrophenol by NaBH4 in presence of gold nanoparticles (NPs) is systematically investigated. Distinctive trends could be identified depending on the extent of the NaBH4 excess. At rather low NaBH4 concentration excess, PVP had a deleterious effect, probably due to the steric hindrance of the PVP layer on the gold surface that acted partially blocking gold active sites. However, under a large excess of NaBH4, an enhanced catalytic performance was observed, what was attributed to the exchange of the polymer by hydride anions and other ions formed during hydrolysis of NaBH4. This exchange occurred without aggregation of NPs and without compromising recycling capability. Based on these results, the design of new routes for the synthesis of supported catalysts based on PVP stabilized metal colloids can be envisaged, as no additional steps would be necessary for removing the stabilizer prior to use.