Stabilization Of Noble Metal Catalysts Supported On Carbon Nanotubes

Proton exchange membrane fuel cell (PEMFC) is one of the most promising cells used for transportation and portable power sources for it has prominent merits such as high efficiency, cleanness and et al. However, the intolerable cost and poor catalysis of the catalyst Pt currently used in PEMFC, together with other technical problems, block PEMFC from commercialization.At present, most of work has been devoted to increase the utilization of platinum (Pt) catalysts and thus to lower the catalyst usage. Multiwall carbon nanotube s (MCNTs) as a new form of carbon, have received researchers'attention due to their unique structural, electronic and mechanical properties. The use of CNTs as alternative supports of catalysts for low-temperature fuel cells has naturally stimulated significant interest among researchers. In recent years there has been a progress in the understanding of that the catalyst-support interaction plays a fundamental role in the performance of catalyst.This paper reports intermittent microwave heating (IMH) or refluence heating plus spontaneous reductuin for preparation of highly dispersed Pt/FCNTs catalysts. At first, MCNTs were functionalized by oxidation of a mixture consisting of H2SO4/H2O2 and formed functional MCNTs (FMCNTs) with oxygen containing groups such as -COOH, -OH, etc. Then the metal ions (Pt4+) were reduced spontaneously on the sidewalls of FMCNTs by the electrons from the FMCNTs without addition of any reductant. X-ray diffraction (XRD) and transmission electron microscopy (SEM) disclosed that the Pt particles were highly dispersed on the FMCNTs support and had a narrow particle distribution with a mean particle size of about 4-5 nm. Cyclic voltammetry demonstrated that the technique evented in this paper for synthesis of Pt/FCNTs catalysts exhibited higher catalytic activity for ORR at room temperature than a commercial Pt/C catalyst. The significant improvement in electrocatalytic activity was due to that the novel technique synthesized Pt nanoparticles was uniform in size and well dispersed on the surface of carbon nanotubes.