Facile removal of polyvinylpyrrolidone (PVP) adsorbates from Pt alloy nanoparticles

The synthesis of colloidal Pt and Pt alloy nanoparticles (NPs) requires surfactants and capping agents to inhibit the overgrowth and aggregation of NPs. These reagents are also needed in the shape control synthesis of NPs to vary crystal growth rates in selected directions. Polyvinylpyrrolidone (PVP) is one of the most common water soluble capping agents for use in the synthesis of colloidal particles. However, PVP strongly adsorbed onto the surface of nanoparticles is detrimental when the NPs are used as catalysts, because surface adsorbed PVP blocks the access of reactant molecules to the active sites of nanoparticles. In this paper, we report a facile NaBH4/tert-butylamine (TBA) treatment technology for the effective removal of PVP from the surface of colloidal Pt-Pd nanocubes (NCs). This method does not change the morphology of the NPs. After treatment, the catalytic activity of Pt-Pd NCs significantly improves due to greater particle surface areas available for catalytic reactions. This facile method will find extensive applications in the fields of fuel cells, water electrolysis and photocatalytic hydrogen production.