Synthesis and Characterization of Platinum Catalysts on Multiwalled Carbon Nanotubes by Intermittent Microwave Irradiation for Fuel Cell Applications

Abstract

Pt electrocatalysts supported on multiwalled carbon nanotube (Pt/MWCNT) nanocomposites have been synthesized by a rapid intermittent microwave irradiation (IMI) technique for polymer electrolyte and direct methanol fuel cells (PEFCs and DMFCs), using H₂PtCl₆ as Pt precursor. The Pt/MWCNT nanocomposites are characterized by XRD, XPS, and TEM. The results indicate that Pt particle size and distribution on the MWCNT support are affected significantly by the oxidation treatment of MWCNTs, the IMI procedure, and the MWCNT tube diameter or surface area. The PtO_x (x = 1, 2) species was first deposited on the surface of MWCNTs by the IMI and subsequently reduced to Pt(0) with refluxing in the presence of HCOOH. Pt/MWCNT nanocomposites synthesized by this IMI method have achieved extremely uniform dispersed Pt nanoparticles with a particle size of ∼3 nm. Electrochemical measurement indicates that Pt/MWCNT nanocomposites synthesized by the IMI method display a significantly higher electrochemically active area and higher catalytic activity for the methanol oxidation reaction in comparison to a commercial Pt/C catalyst.