Abstract:

Catalytically grown carbon nanofibres were treated with a mixture of concentrated nitric and sulphuric acids at different temperatures. The effects of the oxidation treatment on the graphite structure and texture properties were studied by X-ray diffraction and N₂-physisorption. The formation of the surface oxygencontaining groups on the surface of the carbon nanofibers was investigated by DRIFT FTIR and the ionexchange method. The Pd-Pt catalysts supported on the fresh and treated carbon nanofibres were prepared with the incipient wetness impregnation method. The Pd-Pt metal dispersion and the interaction of them with the carriers were studied by the pulses of hydrogen, the high-resolution electron microscopy and the TPRFTIR. The results demonstrated that there were no clear changes of the bulk structure and the texture properties of carbon nanofibers after the treatment in the mixed acids below 150 ℃. The concentration of the formed oxygencontaining surface groups increased with raising the treatment temperatures and it could produce a pronounced promoting effect in the dispersion of metal in the carbon nanofibers. The mechanism of the role of the surface oxygen-containing groups in improving the dispersion of Pd-Pt particles was also discussed.

Key words: Carbon nanofibers; Oxidation treatment; Surface oxygen-containing groups; Supported Pd-Pt metal dispersion