Effect of Platinum Nanoparticle Loading on Oxygen Reduction at a Pt Nanocluster-Activated Microporous–Mesoporous Carbon Support

Very high surface area carbon-supported Pt nanoparticle catalysts have been applied to the oxygen reduction reaction in alkaline solution. The distribution effect of deposited Pt nanoparticles onto the carbon support on the oxygen reduction reaction kinetics has been established by comparing the various carbon-supported Pt (20 and 60 wt% metal) catalysts. The various Pt catalysts were prepared by using a sodium borohydride reduction method. All the catalysts showed a face-centered cubic crystal structure as determined by X-ray diffraction method; the average platinum particle sizes were ∼4.2, ∼4.8, ∼5.4, and ∼27.2 nm for 20 wt% Pt–C(Mo2C), 60 wt% Pt–C(Mo2C)-I, 60 wt% Pt–Vulcan XC72, and 60 wt% Pt–C(Mo2C)-II catalysts, respectively. The X-ray photoelectron spectra for all the catalysts indicated that most of the platinum nanoparticles have an oxidation state of 0. The low-temperature N2 sorption, time-of-flight mass spectrometry, scanning electron microscopy, and transmission electron microscopy experiments have been carried out to characterize the structure of prepared materials. The cyclic voltammetry and rotating disk electrode techniques were used to study the oxygen electroreduction kinetics.