Development of catalytically active silver colloid nanoparticles stabilized by dextran.

Colloidal silver nanoparticles (Ag-NPs) with a mean diameter of 6.1 nm and a narrow size distribution were prepared by reduction of the correspondent metal salt with injection of NaBH4, in the presence of dextran, and characterized by UV–vis, TEM, and DLS. The concentration of all reactants involved in the formation of the nanoparticles was optimized with the use of a new multivariate method, which revealed a significant reduction in the number of experiments when compared with the vast majority of univariate methods described in the literature. The Ag-NPs–dextran composite was able to efficiently catalyze the p-nitrophenol reduction in water by NaBH4 with a rate constant normalized to the surface area of the nanoparticles per unit volume (k1) of 1.41 s–1 m–2 L, which is higher than values ever reported for Ag-NPs catalytic systems.