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In order to reduce the catalyst loading of electrodes for Proton Exchange Membrane Fuel Cells, the Vertically Aligned Carbon Nanotubes (VACNT) grown on Al foil by Plasma Enhanced Chemical Vapor Deposition is introduced as the catalyst support material. The electrode catalyst, Pt was deposited on the VACNT by sputtering deposition for both anode and cathode. The as-prepared electrodes with different Pt loadings were assembled with commercial membrane and gas diffusion layers as five-layer Membrane Electrode Assemblies for single cell performance testing. The morphology and composition of the Pt/VACNT samples were characterized by Scanning Electron Microscopy, Transmission Electron Microscopy and Energy Dispersive X-ray Spectroscopy. The performances and electrochemical properties of the single cells were studied by Polarization Curve and Impedance Spectroscopy. The best utilization of Pt is 0.30 g/kW at maximum power density of 697 mW/cm 2 with Pt loadings of 102 μg/cm 2 at cathode and 108 μg/cm 2 at anode, which is 21% increasing as compared to that of the commercial catalyst under the identical conditions. [ABSTRACT FROM AUTHOR]

Abstract: In situ grown carbon nanotubes (CNTs) on carbon paper as an integrated gas diffusion layer (GDL) and catalyst layer (CL) were developed for proton exchange membrane fuel cell (PEMFC) applications. The effect of their structure and morphology on cell performance was investigated under real PEMFC conditions. The in situ grown CNT layers on carbon paper showed a tunable structure under different growth processes. Scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) demonstrated that the CNT layers are able to provide extremely high surface area and porosity to serve as both the GDL and the CL simultaneously. This in situ grown CNT support layer can provide enhanced Pt utilization compared with the carbon black and free-standing CNT support layers. An optimum maximum power density of 670mWcm−2 was obtained from the CNT layer grown under 20cm3 min−1 C2H4 flow with 0.04mgcm−2 Pt sputter-deposited at the cathode. Furthermore, electrochemical impedance spectroscopy (EIS) results confirmed that the in situ grown CNT layer can provide both enhanced charge transfer and mass transport properties for the Pt/CNT-based electrode as an integrated GDL and CL, in comparison with previously reported Pt/CNT-based electrodes with a VXC72R-based GDL and a Pt/CNT-based CL. Therefore, this in situ grown CNT layer shows a great potential for the improvement of electrode structure and configuration for PEMFC applications. [Copyright &y& Elsevier]

Abstract: An efficient fabrication method for carbon nanotube (CNT)-based electrode with a nanosized Pt catalyst is developed for high efficiency proton-exchange membrane fuel cells (PEMFC). The integrated Pt/CNT layer is prepared by in situ growth of a CNT layer on carbon paper and subsequent direct sputter-deposition of the Pt catalyst. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrate that this Pt/CNT layer consists of a highly porous CNT layer covered by well-dispersed Pt nanodots with a narrow size distribution. Compared with conventional gas-diffusion layer assisted electrodes, the CNT-based electrode with a Pt/CNT layer acting as a combined gas-diffusion layer and catalyst layer shows pronounced improvement in polarization tests. A high maximum power density of 595mWcm−2 is observed for a low Pt loading of 0.04mgcm−2 at the cathode. [Copyright &y& Elsevier]

Abstract: Multi-walled carbon nanotubes (MWCNTs) are functionalized with 2-pyrridone functional groups by wrapping poly(vinylpyrrolidone) polymers around it under high-powered sonication. The presence of 2-pyrridone functional groups facilitates the complexation of metal ions (Fe3+, Co2+). The best oxygen reduction catalyst, MWCNT–FeCo, is synthesized by annealing poly(vinylpyrrolidone)/MWCNTs/Fe–Co complex in ammonia at 900°C and exhibits nearly four-electron oxygen pathway (n ∼3.8). X-ray diffraction pattern shows that low loading of metallic Fe nanoparticles (0.79wt.%) and bimetallic FeCo nanoparticles (0.34wt.%) is formed on the MWCNT–FeCo catalysts. X-ray photoelectron spectroscopy reveals that ∼1at.% of nitrogen has been doped into MWCNT–FeCo catalysts. [Copyright &y& Elsevier]