High Pt loading on functionalized multiwall carbon nanotubes as a highly efficient cathode electrocatalyst for proton exchange membrane fuel cells

Abstract

A very efficient, reproducible approach has been developed to fabricate a multiwall carbon nanotube (MWCNT)-supported, high Pt loading electrocatalyst. In this strategy, MWCNT was first functionalized with an anionic surfactant, sodium dodecylsulfate (SDS), to enhance the hydrophilicity of the MWCNTs for high Pt loading. The SDS-modified MWCNTs were further used to support high loading of Pt nanoparticles (NPs) through a urea-assisted homogeneous deposition (HD) strategy, followed by reduction using ethylene glycol (EG) as the precursor of a reducing agent. Through the input of SDS on the MWCNTs, Pt complex species can be readily anchored on the outer surface of the MWCNTs, while in situ pH adjustment of the solution with urea and reduction by EG enable the Pt NPs to disperse very uniformly on the SDS–MWCNT support with small particles size. Due to its unique structural characteristics, such as high electronic conductivity, the one-dimensional nanotube structure favouring fast electron transfer and more uniform Pt NP dispersion on the support with smaller particle size, the SDS-MWCNT-supported Pt (60 wt%) catalyst considerably outperformed a commercially available Johnson Matthey catalyst with the same Pt loading supported on Vulcan carbon black, when they were each employed as a cathode catalyst in proton exchange membrane fuel cells.