Environmentally Friendly Fabrication of Surface-Modified MWNT-Supported Pt Nanocomposites for PEMFCs

The functionalisation process of carbon nanotubes (CNTs) is required as a primary step in fabricating CNTs-supported composites. In this study, multi wall carbon nanotubes (MWNTs) were treated under N-2 atmospheric pressure plasma in order to functionalise their sidewalls with nitrogen-containing and other functional groups. The surface-treated MWNTs with -NO, -NH2 and other functional groups grafted on their sidewalls were analysed by X-ray photoelectron spectroscopy (XPS). In addition, a certain amount of structural disorder generated by the continuous decoration of functional groups on the MWNT sidewalls was investigated by Raman spectroscopy and high-resolution transmission electron microscopy (TEM). The functional groups introduced by N-2 atmospheric pressure plasma were used as the chemical reaction sites for fabricating the Pt/MWNT nanocomposites. The deposition manner of Pt nanoparticles from their precursor ions (PtCl62-) was positively correlated with the proportion of the surface functional groups. The plasma-treated MWNT-supported platinum catalysts exhibited higher electrochemical activity for hydrogen adsorption/desorption and methanol oxidation than did the catalysts prepared with MWNTs treated by HNO3/H2SO4. These results were due to the uniformly deposited Pt nanoparticles on the MWNTs caused by the strong interactions between the Pt precursors and the functional groups formed by N-2 atmospheric pressure plasma.