Graphene Aerogel Supported Pt Electrocatalysts for Oxygen Reduction Reaction by Supercritical Deposition

Mesoporous graphene aerogel (GA) supported Pt nanoparticles with narrow size distribution were prepared via supercritical deposition (SCD) using supercritical CO 2 (scCO 2 ). Pt(cod)me 2 precursor was dissolved in scCO 2 and adsorbed onto GA at 35 °C and 10.7 MPa. The Pt precursor was converted to its metal form under atmospheric pressure at various temperatures. The effects of precursor conversion temperature (400, 600, and 800 °C) on the structural properties of the composites were investigated using Raman Spectroscopy, XRD, XPS, and TEM. The average particle size increased from 1.2 to 2.9 nm when the conversion temperature was increased from 400 to 800 °C. The electrocatalytic activity of the samples towards the Oxygen Reduction Reaction were evaluated using cyclic voltammetry (CV) and rotating disc electrode (RDE) measurements. SCD helped to preserve the textural properties of the GA after the Pt nanoparticle deposition, and thus Pt/GA converted at 600 °C exhibited an enhanced mass activity of 30.6 mA mg Pt −1 , outperforming the mass activities reported in the literature for Pt/GA electrocatalysts prepared using conventional routes.