Electrochemical Investigation of pH-Dependent Activity of Polyethylenimine-Capped Silver Nanoparticles

The pH-dependent electroanalytical behavior and catalytic activity of branched polyethylenimine-capped silver nanoparticles (PEI-AgNPs) were studied by using nanoparticle collision electrochemistry, linear sweep voltammetry, and UV/Vis spectroscopy. The electrochemical collision signals respond rapidly to pH-induced protonation of the PEI chain at the AgNP surface. This method allows for screening and catalytic activity evaluation of PEI-AgNPs for the decomposition of organic dyes, demonstrated in this work with methylene blue. Higher oxidation of PEI-AgNPs was observed at neutral and basic pH, when the particles are stabilized by the PEI chain. Cumulatively, these results indicate that NP collision electrochemistry can be used in addition to spectroscopy and microscopy for studying the effect of the capping agent on the electrochemical behavior of AgNPs and evaluating the relationship between the surface properties and catalytic activity. These measurements provide fundamental information about how surface characteristics, environment, and capping ligands affect NP properties and activity.