Synthesis and characterization of carbon nanotubes supported platinum nanocatalyst for proton exchange membrane fuel cells

摘要

Multi-walled carbon nanotubes (MWCNTs) were used as catalyst support for depositing platinum nanoparticles by a wet chemistry route. MWCNTs were initially surface modified by citric acid to introduce functional groups which act as anchors for metallic clusters. A two-phase (water-toluene) method was used to transfer PtCl_6~(2-) from aqueous to organic phase and the subsequent sodium formate solution reduction step yielded Pt nanoparticles on MWCNTs. High-resolution TEM images showed that the platinum particles in the size range of 1-3 nm are homogeneously distributed on the surface of MWCNTs. The Pt/MWCNTs nanocatalyst was evaluated in the proton exchange membrane (PEM) single cell using H_2/O_2 at 80=C with Nafion-212 electrolyte. The single PEM fuel cell exhibited a peak power density of about 1100 mW cm~(-2) with a total catalyst loading of 0.6 mg Pt cm~(-2) (anode: 0.2 mg Pt cm~(-2) and cathode: 0.4 mg Pt cm~(-2)). The durability of Pt/MWCNTs nanocatalyst was evaluated for 100 h at 80℃ at ambient pressure and the performance (current density at 0.4 V) remained stable throughout. The electrochemi-cally active surface area (64 m~2 g~(-1)) as estimated by cyclic voltammetry (CV) was also similar before and after the durability test.