Control of average particle size of carbon aerogel supported platinum nanoparticles by supercritical deposition

• DOI: 10.1016/j.micromeso.2017.01.037
• Publication Date: 2017-01-30T19:17:56Z
• Authors: Şansım Bengisu Barım; Ayşe Bayrakçeken; Selmi Erim Bozbağ; Lichun Zhang; Rıza Kızılel; Mark Aindow; Can Erkey
• Keywords: 02 engineering and technology; 0210 nano-technology

Abstract Supercritical deposition was used to synthesize Pt/carbon aerogel (Pt/CA) electrocatalysts. CAs with average pore diameters of 6, 8 and 19 nm (CA6, CA8 and CA19, respectively) were synthesized and impregnated with Pt(cod)me 2 precursor using supercritical carbon dioxide followed by the thermal conversion of the Pt precursor into its metallic form under N 2 atmosphere at various temperatures between 200 and 1000 °C. All of the prepared CAs have high surface areas with very sharp pore size distributions. XRD and TEM results show increased Pt particle size with increasing conversion temperature with a homogenous distribution of nanoparticles on the CA supports. Cyclic voltammetry was used to determine the effect of CA pore properties on electrocatalytic activity. At a conversion temperature of 400 °C, the highest and lowest electrochemical surface area values were obtained for Pt/CA19 and Pt/CA6 of (126 and 36 m 2 /g, respectively). Furthermore, Pt/CA19 showed good mass activity whereas Pt/CA6 and Pt/CA8 had lower activity values towards the Oxygen Reduction Reaction (ORR). The mass activity values for Pt/CA19 increased with increasing conversion temperature, except for the sample converted at 1000 °C which exhibited the lowest mass activity. The specific activity increased significantly with the conversion temperature up to 600 °C which gave a value six times that obtained at 200 °C. At 800 °C, the specific activity decreased slightly, probably due to a change in the CA structure at this elevated conversion temperature. The Pt/CA19 sample converted at 600 °C exhibited the best performance with a mass activity of 0.1 A/mg Pt and a specific activity of 0.24 mA/cm 2 .