Pt/C Electrocatalyst Durability Enhancement By Inhibition Of Pt Nanoparticle Growth Through Microwave Pretreatment Of Carbon Support

Durability enhancement of Pt supported on carbon (Pt/C) electrocatalysts through a simple microwave (MW) pretreatment of the carbon support has been studied. Vulcan XC 72 carbon (either in suspension or dry state) was subjected to MW irritation for a short period of time (similar to 5 min) prior to synthesis of the Pt/C electrocatalysts (20 wt.% Pt) through a polyol route. Platinum deposited onto MW-pretreated and unmodified carbons demonstrated similar initial Pt particle size distributions (average particle size similar to 3.3 nm) and electrochemical surface area (ECSA). However, ECSA evolution based on an accelerated stress test (AST) in acidic conditions suggested a clear durability enhancement of the MW-pretreated Pt/C samples over the unmodified equivalent. Transmission electron microscope (TEM) images of the post-AST samples reveal spherical and nanorod morphologies of the Pt nanoparticles for the untreated and the MW-pretreated carbon supports, respectively. X-ray photoelectron spectroscopy (XPS) evidences presence of surface active sites (C-O*) on the carbon support generated from the MW irradiation. Those active sites turned out to be suitable nucleation sites for redeposition of the dissolved Pt species to form new Pt nanoparticles during AST. The mechanism reduces the rate of Pt nanoparticle active surface area loss, and thus provides increased durability. The proposed concept opens a new territory for a scalable process to further advance the electrocatalyst.