The Effect of Poly(vinylpyrrolidone) (PVP) on the Au Catalyzed Reduction of p–nitrophenol: The Fundamental Role of NaBH 4 .

Abstract The effect of polymeric ligands, like poly(vinylpyrrolidone) (PVP), on the reduction of p‐nitrophenol by NaBH 4 in presence of gold nanoparticles (NPs) is systematically investigated. Distinctive trends could be identified depending on the extent of the NaBH 4 excess. At rather low NaBH 4 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 NaBH 4 , 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 NaBH 4 . 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.