Chemical Functionalization of Carbon Supported Metal Nanoparticles by Ionic Conductive Polymer via the "Grafting From" Method
Résumé
favor Platinum nanoparticles (Pt-NPs) supported on carbon powder are prepared via a water-in-oil microemulsion method and modified by a disulfide aryl initiator either by a postgrafting method or by a one pot in situ "grafting from" method. It is shown that the grafting of the disulfide derivation initiator is quantitative from 2 to 10 wt %, independently on the method. ATRP of sodium styrene sulfonate (SSNa) has then been performed from the initiator molecules grafted on the surface of the Pt-NPs supported on an electron conductive porous substrate and electrochemical measurements are performed. Although the polymerization reaction was not total (60%), derivatization of the Pt-NPs-initiator/C with different polymerization densities and polymer molecular weights are obtained. Electrodes fabricated from such nanocomposites shows enhanced performances toward the oxygen reduction reaction. Higher activity is obtained with lower polymerization density and higher polymer molecular weight. The enhancement of activity is attributed to the difference in hydrophilic character between the polymer skeleton (which could favor oxygen transport toward active sites) and the pendant sulfonic acid groups (which favor the proton transport toward the active sites).