Synthesis and catalytic properties of silver nanoparticle-linear polyethylene imine colloidal systems

The excellent catalytic properties of colloidal metal nanoparticles (M-NPs), such as good selectivity, efficiency, and recyclability, have attracted great interest in academic and industrial research. However, new M-NP stabilizers/supports still need to be developed and their performance needs to be better understood. Herein, we report an approach for effectively combining a high-throughput method using linear polyethylene imine (LPEI) with in situ screening and multivariate optimization of the synthesis conditions to produce highly catalytically stable Ag-NPs. Selected Ag-NP/stabilizers were able to efficiently catalyze the p-nitrophenol (Nip) reduction by NaBH ₄ in water with a rate constant normalized to the surface area of the nanoparticles per unit volume (k ₁) up to 1.66 s ^-1 m ^-2 L. A full kinetic analysis based on the Langmuir model indicates that the Nip molecules have a much stronger adsorption affinity than BH ₄ ^- ions for the Ag-NP surface and all species are likely adsorbed and accommodated on the surface before they take part in any reaction.