Carbon Black Vulcan XC-72 Research Articles

Nanoparticles enrichment to carbon felt electrodes for non-aqueous redox flow battery

Non-aqueous electrolytes enable redox flow batteries to achieve higher energy density. However, commercially available, pristine carbon felt electrodes display high overpotentials for electrochemical reactions in a non-aqueous medium. It is then crucial to develop stable high-performance electrodes which display low activation overpotentials, low ohmic losses, and high porosity to ensure uniform flow-through distribution of the electrolyte. This study acknowledges the influence of using attached carbon-based nanoparticles to the fibers of the supporting carbon-felt electrodes. The use of reduced graphene oxide, graphene, multi-walled carbon nanotubes (CNT), carbon black Vulcan XC72, and Ketjen carbon nanoparticles bounded to the support carbon felt electrode using a Nafion ionomer was assessed. Post-mortem analysis revealed that the nanoparticles remained attached to the fibers even after intense charge-discharge cycling. The carbon felt containing CNT added to the fibers displayed the best performance on running the charge/discharge electrochemical reactions while achieving a 23 % higher energy efficiency compared to commonly used electrodes. The addition of noble metal-based nanoparticles Pt-rGO displayed only a slightly better performance of rGO. Good binding of the carbon nanoparticles was obtained by the addition of the ionomer in a ratio of 15 wt%.

Pt-Mo/C, Pt-Fe/C and Pt-Mo-Sn/C Nanocatalysts Derived from Cluster Compounds for Proton Exchange Membrane Fuel Cells

Nanosized bimetallic PtMo, PtFe and trimetallic PtMoSn catalysts deposited on highly dispersed carbon black Vulcan XC-72 were synthesized from the cluster complex compounds PtCl(P(C6H5)3)(C3H2N2(CH3)2)Mo(C5H4CH3)(CO)3, Pt(P(C6H5)3)(C3N2H2(CH3)2)Fe(CO)3(COC6H5C2C6H5), and PtCl(P(C6H5)3)(C3N2H2(CH3)2)C5H4CH3Mo(CO)3SnCl2, respectively. Structural characteristics of these catalysts were studied using X-ray diffraction (XRD), microprobe energy dispersive spectroscopy (EDX), and transmission electron microscopy (TEM). The synthesized catalysts were tested in aqueous 0.5 M H2SO4 in a three-electrode electrochemical cells and in single fuel cells. Electrocatalytic activity of PtMo/C and PtFe/C in the oxygen reduction reaction (ORR) and the activity of PtMoSn/C in electrochemical oxidation of ethanol were evaluated. It was shown that specific characteristics of the synthesized catalysts are 1.5–2 times higher than those of a commercial Pt(20%)/C catalyst. The results of experiments indicate that PtFe/C, PtMo/C, and PtMoSn/C catalysts prepared from the corresponding complex precursors can be regarded as promising candidates for application in fuel cells due to their high specific activity.

Pd-Pt nanoparticles combined with ceria nanorods for application in oxygen reduction reactions in alkaline direct ethanol fuel cell cathodes

Fuel cells are important energy conversion devices. However, challenges in this regard are still noted, such as low electrocatalyst efficiencies in the oxygen reduction reaction (ORR), which occurs slowly in electrocatalyst cathodes. In this sense, this study aimed to synthetize hybrid binary and ternary electrocatalysts formed by palladium and platinum alloy nanoparticles and ceria nanorods (CeO2 NR) supported on carbon black Vulcan XC-72 (PdxPty/Vn and (Pd3Pt1)x(CeO2 NR)y(Vn)z) for the study of the oxygen reduction reaction (ORR) and application as alkaline direct ethanol fuel cells (ADEFCs) cathodes. The binary and ternary hybrid electrocatalysts were characterized using different physicochemical and electrochemical techniques. The ternary hybrid electrocatalyst, (Pd3Pt1)15(CeO2 NR)10(Vn)75, reached higher open circuit voltage (OCV), maximum current and power densities, of 1.13 V, 219 mA cm-2 and 61 mW cm-2, respectively, compared to the commercial Pt/C Alfa Aesar (AA) and other evaluated electrocatalysts. The ternary hybrid electrocatalyst, (Pd3Pt1)15(CeO2 NR)10(Vn)75, is interesting for application as an ADEFC cathode targeting the ORR, due to an almost 3-fold maximum power density and almost twice the maximum current density compared to a commercial electrocatalyst with the same noble metal loading, explained by increased defects and oxygenated species in this electrocatalyst as revealed by Fourier Transform Infrared Spectroscopy (FT-IR) and Raman analyses.

Bifunctional FeCoP/C electrocatalyst toward overall water splitting by application of various dimensional carbon materials

Water electrolysis is a green, safe, and practical route for hydrogen refueling station, but now it confronts a big challenge of extremely high electrical energy consumption. Thus, lower the voltage of an electrolyzer is one of the critical routes to solve this issue. Here we apply carbon black Vulcan XC-72, carbon nanotubes, and graphene oxide (named as 3C) to construct an effective bifunctional iron cobalt phosphide (FeCoP/3C) electrocatalyst, the electrocatalytic activity toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) was respectively investigated. The FeCoP/3C electrocatalyst shows overpotential of 220 mV and 120 mV at current density of 10 mA cm−2, Tafel slope of 73 mV dec−1 and 129 mV dec−1 for OER and HER in 1 M KOH electrolyte, respectively. When the electrocatalyst is used to construct an overall water electrolyzer, a cell voltage of 1.597 V can be achieved at current density of 10 mA cm−2. Moreover, the FeCoP/3C displays excellent durability toward overall water splitting, because the current density retains 92% after working for 10 h continuously. This outstanding performance is mainly attributed to the electrocatalyst possessing excellent electrical conductivity, exposing sufficient active sites, facilitating fast ions transportation and electron transfer, as well as speeding up O2 and H2 release. Therefore, this FeCoP/3C electrocatalyst can be a promising bifunctional electrocatalyst for practical overall water splitting.

The study of the pyrolysis products of Ni (II) and Pd (II) chelate complexes as catalysts for the oxygen electroreduction reaction

Nitrogen-doped carbon materials were prepared by the pyrolysis of carbon black Vulcan XC-72 impregnated with nitrogen-containing Pd (II) and Ni (II) complexes. The composition of materials was studied at different stages of their synthesis. It is shown that nanoparticles of metals and/or their oxides are not the main electroactive component of materials in the oxygen electroreduction reaction (ORR). It is established that the palladium complex provides a much more efficient doping of carbon with nitrogen compared to the nickel complex of a similar composition. This results in the high ORR electrocatalytic activity of the catalyst obtained, palladium complex being used in an alkaline medium. This material is a promising one to be used as an electrocatalyst in fuel cells with an anion-conducting membrane.

Influence of Carbon Support on Catalytic Layer Performance of Proton Exchange Membrane Fuel Cells

Pt-based catalysts supported onto various carbon nanotubes (CNTs) and carbon black Vulcan XC-72 have been studied in this work. The samples have been prepared via electrochemical dispersion technique. The carbon nanotubes exhibit the mesoporous morphology with the pore size of 5—30 nm, while Vulcan XC-72 support exhibits a microporous structure. The agglomeration of Pt particles (5—7 nm) is found to be more extended at the carbon nanotubes compared to the carbon black. The examination of the synthesized catalysts in a catalytic membrane electrode assembly layer reveals that CNTs favor a power density higher than in the carbon black support owing to a more suitable porous structure of the catalyst layer. Moreover, the maximum characteristics of membrane electrode assembly are obtained for few-walled carbon nanotubes with a broad carbon having size distribution.

Pd-Based Electrocatalysts Prepared by Borohydride Reduction Method for Methanol and Ethanol Electro-Oxidation in Alkaline Medium

Pd/C, Au/C, AuBi/C, PdAu/C, PdAuBi/C electrocatalysts (with different atomic ratios and 20 wt% of metal loading) were prepared by borohydride reduction method using a water/2-propanol mixture as solvent, Pd (NO3)2.2H2O, HAuCl4.3H2O and Bi (NO3)3.5H2O as metal sources, carbon black Vulcan XC72 as support and NaBH4 as reducing agent. The activities of the prepared electrocatalysts for methanol and ethanol electro-oxidation in alkaline medium were investigated by chronoamperometry using the thin porous coating technique. Chronoamperometry experiments showed that PdAu/C (Pd:Au atomic ratio of 50:50) has superior activity and stability for methanol and ethanol electro-oxidation compared with other catalysts.

Platinum/nitrogen-doped carbon nanoparticles synthesized in nitrogen-doped carbon quantum dots aqueous solution for methanol electro-oxidation

Platinum-based catalysts are a key to develop direct methanol fuel cells, which are usually dispersed on carbon supports to enhance catalytic activity, stability and utilization. Here, platinum/nitrogen-doped carbon (Pt/N-C) nanoparticles are synthesized in nitrogen-doped carbon quantum dots (N-CQDs) aqueous solution, and catalytic performance of Pt/N-C catalysts is researched for methanol electro-oxidation. Compared with Pt catalysts supported on commercial carbon black Vulcan XC-72 (Pt/XC-72), the peak current densities of Pt/N-C catalysts are 0.59mAcm−2 Pt and 385.2Ag−1 Pt in 0.5M CH3OH and 0.5M H2SO4, while those of Pt/XC-72 catalysts are 0.39mAcm−2 Pt and 64.8Ag−1 Pt. After polarizing 7200s at a fixed potential of 0.15V (vs. Hg/Hg2SO4), the catalytic activities of Pt/N-C are 0.14mAcm−2 Pt and 86.5Ag−1 Pt, and those of Pt/XC-72 are 0.02mAcm−2 Pt and 2.6Ag−1 Pt.

Electrochemical Evaluation of Pt-Based Binary Catalysts on Various Supports for the Direct Methanol Fuel Cell

Multi-walled carbon nanotubes (MWCNTs), TiO2, MoO2, and carbon black Vulcan XC-72 were investigated as supports for PtRu and PtSn catalysts. X-ray diffraction (XRD) confirmed that all electrocatalysts examined display characteristic patterns similar to that of the Pt/C electrocatalyst, an indication that the catalysts have predominantly the Pt face-centered cubic (fcc) crystal structure. High-resolution transmission electron microscopy (HRTEM) images showed spherical PtRu and PtSn nanoparticles with a narrow particle size distribution, dispersed on the support materials. The metal loading for the prepared electrocatalyst was estimated using energy-dispersive X-ray spectroscopy (EDS), and it was observed to be closest to that of the catalysts supported on Vulcan XC-72. Cyclic voltammograms showed PtSn/C to be the most active, as it possessed a higher electroactive surface area than that of the other catalysts, followed by Pt/C > PtRu/MWCNT > PtRu/C > PtSn/MWCNT > PtSn/MoO2 > PtRu/MoO2 > PtSn/TiO2 > PtRu/TiO2. It was also observed that catalysts supported on MWCNTs were more active than those supported on metal oxides. Furthermore, catalysts supported on MWCNTs proved to be more stable than all the other supported catalysts examined. Therefore, MWCNTs have been proven in this study to be the best material for supporting electrocatalysts for direct methanol fuel cells.

Binary and Ternary Catalysts Based on Pt, Au and Ni for the Oxygen Reduction Reaction

Proton exchange membrane fuel cells (PEMFC) are currently considered as an alternative to fossil fuels for transportation, stationary, aeronautics applications1… However, the activation of oxygen reduction reaction (ORR) at the cathode of PEMFC has been and remains a key challenge to make this technology marketable. Indeed, oxygen reduction reaction has a low kinetics and requires catalyst to be activated. Platinum is known to be the most active electrocatalyst for this reaction. The disadvantages of platinum based catalysts are their high cost and low durability. Then several studies were carried out for the last decades in order to develop new catalysts both to improve the catalytic activity and the durability, and to reduce the platinum loading at the cathode. Studies indicated that structural and electronic effects involved in Pt alloys or core shell structures (with metals such as Au, Ni, Fe, Co) enhance the catalytic activity 2, 3. Recent works on Pt3M (M= Ni, Fe, Co) showed considerable improvement of catalytic activity toward the ORR4. It was also shown that the durability could significantly be improved by alloying Pt with Au. This contribution presents a comparative study of the ORR on monometallic, alloyed binary and ternary nanocatalysts based on Pt, Ni and Au. Water-in-oil microemulsion method has been implemented for synthesizing Pt/C, Au/C, PtxM1-x/C (M= Ni, Au) and PtxNiyAuz/C nanocatalysts supported on a carbon black Vulcan XC-72 support. Nanocatalysts were comprehensively characterized by atomic absorption and thermogravimetric analysis in order to determine bulk chemical compositions and metal loadings. The morphology of catalysts and the particle sizes were determined by transmission electron microscopy (TEM). X-ray diffraction (XRD) studies allowed determining their microstructure (crystallite size and alloy formation). The surface composition was determined by X-Ray photoelectron spectrometry (XPS) and electrochemical analyses. The catalytic activity and the selectivity of the nanocatalysts toward the ORR have been determined by rotating disc electrode (RDE) and rotating ring disc electrode (RRDE) in O2-saturated 0.1 M HClO4 electrolyte. It was shown that the catalytic activity of PtxAu1-x/C nanocatalysts is maintained up to 50 at % of gold in the alloy. The addition of Ni to Pt allows improving the catalytic activity in comparison to that recorded on pure Pt/C catalyst (figure 1), with an optimum for a Pt3:Ni1 ratio. Hence, different ternary PtxNiyAuz/C catalysts were synthesized keeping the Pt:Ni ratio 3:1, and their catalytic activities were determined, as well as their selectivity towards the 4-electron process. [1] C. Coutanceau, S. Baranton, “Advanced Processes in Catalytic Oxidation - Oxygen Activation in Fuel Cells and Electrocatalytic Processes”, in “From Laboratory Studies to Industrial Applications", D. Duprez and F. Cavani (Eds.), Imperial College Press, London, 2014. [2] F. H. B. Lima, J. Zhang, M. H. Shao, K. Sasaki, M. B. Vukmirovic, E. A. Ticianelli, R. R. Adzic, J. Phys. Chem. C 2007, 111, 404-410. [3] M. T. Paffet, J. G. Beery, S. Gottesfeld, J. Electrochem. Soc. 135 (1988) 1431. [4] T. Toda, H. Igarashi, H. Uchida, M. Watanabe, J. Electrochem. Soc. 1999, 146, 3750. Acknowledgement: This work was made under the framework of the SMARTCat project funded by the European Commission under the FP7 Fuel Cells and Hydrogen Joint Technology Initiative grant agreement FP7-2012-JTI-FCH-325327. Figure 1

Molten salts synthesis of tin dioxide/nitrogen-doped carbon composite as Pt catalyst support for methanol electro-oxidation

Tin dioxide/nitrogen-doped carbon composite was prepared from tin oxide/polyaniline composite by using LiCl–KCl molten salt and used as Pt catalyst support for methanol electro-oxidation. Transmission electron microscope showed that tin dioxide was uniformly distributed on the surface of nitrogen-doped carbon without obvious agglomeration. Compared with Pt catalysts supported by commercial carbon black Vulcan XC-72 and EC300J, the current density of Pt catalysts supported by the as-prepared support was more than 2 times higher after polarizing 1000 s at a fixed potential of 0.15 V (vs. Hg/Hg2SO4), exhibiting increased activity and stability for methanol electro-oxidation. Moreover, onset potential of Pt catalyst supported by the as-prepared support was nearly 0.1 V lower than that of Pt catalyst supported by EC300J.

Acid-treated PtSn/C and PtSnCu/C electrocatalysts for ethanol electro-oxidation

PtSn/C with Pt:Sn atomic ratio of 50:50 and PtSnCu/C electrocatalysts with different Pt:Sn:Cu atomic ratios were prepared using NaBH4 as reducing agent and carbon black Vulcan XC72 as support. In a second step, the electrocatalysts were treated with nitric acid to remove the less noble metals (chemical dealloying). The obtained materials were characterized by X-ray diffraction, EDX analysis, TEM images with EDX scan-line and cyclic voltammetry. The electro-oxidation of ethanol was studied by chronoamperometry and on single direct ethanol fuel cell (DEFC). The X-ray diffractograms of the as-synthesized electrocatalysts showed the typical face-centered cubic (FCC) structure of Pt alloys. After acid treatment the FCC structure was maintained and Sn and Cu atoms were removed from the nanoparticles surface. Chronoamperometry measurements showed a strong increase of performance of PtSn/C and PtSnCu/C electrocatalysts after acid treatment; however, under DEFC conditions at 100 °C, only acid-treated PtSn/C electrocatalyst showed superior performance compared to commercial PtSn/C from BASF.

Reduction free room temperature synthesis of a durable and efficient Pd/ordered mesoporous carbon composite electrocatalyst for alkaline direct alcohols fuel cell

The development of easy and environmentally benign synthesis methods of efficient electrocatalysts for use in energy conversion applications motivates researchers all over the world. Here we report a novel and versatile method to synthesize well-dispersed palladium-functionalized ordered mesoporous carbons (Pd–OMCs) at room temperature without any reducing agent by one-pot mixing of tri(dibenzylideneacetone)palladium(0) (Pd2DBA3) and OMCs together in a common N,N-dimethylformamide (DMF) solution. The formation of Pd nanoparticles and their crystallization on the OMC is catalyzed by protons in the solution and can thus be controlled by the solution pH. The complete process and the as-prepared nanocomposite was characterized by UV-spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrum (XPS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The electrocatalytic property of the decorated material was examined with cyclic voltammetry (CV). The Pd–OMC composite shows up to two times higher electrocatalytic ability with a significantly better durability towards ethanol and methanol oxidation in alkaline media compared to commercial high surface area conductive carbon black Vulcan XC-72 decorated with equivalent Pd nanoparticles. Our described method provides new insight for the development of highly efficient carbon based nanocatalysts by simple and environmentally sound methods.

Ni/Carbon Hybrid Prepared by Hydrothermal Carbonization and Thermal Treatment as Support for PtRu Nanoparticles for Direct Methanol Fuel Cell

Ni/Carbon was prepared in two steps: initially cellulose as carbon source and NiCl2·6H2O as catalyst of the carbonization process were submitted to hydrothermal treatment at 200 °C and further to thermal treatment at 900 °C under argon atmosphere. The obtained material contains Ni nanoparticles with face-centered cubic (fcc) structure dispersed on amorphous carbon with graphitic domains. PtRu/C electrocatalysts (carbon-supported PtRu nanoparticles) were prepared by an alcohol-reduction process using Ni/Carbon as support. The materials were characterized by thermogravimetric analysis, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and tested as anodes in single direct methanol fuel cell (DMFC). The performances of PtRu/C electrocatalysts using Ni/Carbon as support were superior to those obtained for PtRu/C using commercial carbon black Vulcan XC72 as support.

Carbon supported Ag nanoparticles as high performance cathode catalyst for H2/O2 anion exchange membrane fuel cell.

A solution phase-based nanocapsule method was successfully developed to synthesize non-platinum metal catalyst—carbon supported Ag nanoparticles (Ag/C). XRD patterns and TEM image show Ag nanoparticles with a small average size (5.4 nm) and narrow size distribution (2–9 nm) are uniformly dispersed on the carbon black Vulcan XC-72 support. The intrinsic activity and pathway of oxygen reduction reaction (ORR) on the Ag/C and commercial Pt/C were investigated using rotating ring disk electrode (RRDE) tests at room temperature. The results confirmed that the 4-electron pathway of ORR proceeds on small Ag nanoparticles, and showed comparable ORR activities on the self-prepared Ag/C and a commercial Pt/C. A single H2-O2 anion exchange membrane fuel cell (AEMFC) with the Ag/C cathode catalyst exhibited an open circuit potential of 0.98 V and a peak power density of 190 mW/cm2 at 80°C.

Preparation of PtSn/C Skeletal-Type Electrocatalysts for Ethanol Electro-Oxidation

PtSnCu/C electrocatalysts were synthesized with 20 wt% of metals loading and different Pt:Sn:Cu atomic ratios by borohydride reduction method using 2-propanol as solvent, H2PtCl6.6H2O, SnCl2.2H2O and CuCl2.2H2O as metals sources, NaBH4 as reducing agent and carbon black Vulcan XC72 as support. In a second step, the electrocatalysts were treated with nitric acid. The obtained materials were characterized by X-ray diffraction and EDX analysis. The electro-oxidation of ethanol was studied by chronoamperometry in acid medium at room temperature. The X-ray diffractograms of the as-synthesized electrocatalysts showed the typical face-centered cubic (FCC) structure of Pt and Pt alloys. After treatment with nitric acid the X-ray diffractrograms showed that the FCC structure was preserved and EDX analysis that Sn an Cu were partially removed. The results obtained by chronoamperometry showed for all electrocatalysts an increase of performance for ethanol electro-oxidation after acid treatment.

Nanostructured tungsten carbide/carbon composites synthesized by a microwave heating method as supports of platinum catalysts for methanol oxidation

In this work, a series of nanostructured tungsten carbide/carbon (WC/C x ) composites are in situ synthesized using a microwave heating method. The composites are used as platinum (Pt) catalyst supports for methanol oxidation in acid media. Their structure, composition and specific surface area are characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), Raman spectroscopy, and Brunauer–Emmett–Teller (BET) measurements. Platinum catalysts supported on the WC/C x composites are synthesized by an improved impregnation method. The electrochemical performance and stability of the catalysts are evaluated by cyclic voltammetry (CV) and chronoamperometry (CA). The Pt/WC/C x catalysts exhibit higher activity and stability than does the Pt/VC (Pt supported on carbon black Vulcan XC-72) catalyst. The results indicate that there is a synergistic effect between Pt and the WC/C x support, which can promote the electrocatalysis of Pt for methanol oxidation reaction (MOR).

Enhanced activity observed for sulfuric acid and chlorosulfuric acid functionalized carbon black as PtRu and PtSn electrocatalyst support for DMFC and DEFC applications

In this study, carbon black Vulcan XC72 was successfully functionalized in an autoclave with sulfuric acid (SA) and Chlorosulfuric acid (C-SA). The functionalized carbons were then used as supports to prepare PtRu/C and PtSn/C electrocatalysts by an alcohol-reduction process. Physical characterization was performed by BET, LS, XRD, EDX, and TEM. The electrochemical characterization showed that the catalysts supported on functionalized carbons exhibited better performance for alcohol oxidation if compared to those using unfunctionalized supports. The observed better performance can be mainly attributed to the easier access with protons (higher ionic transport), better wettability (higher water uptake), and better distribution of the nanoparticles over the support (higher platinum utilization); indicating that sulfonation is an efficient approach to functionalize, improve performance, and reduce costs of fuel cell catalysts.

Nanoscale graphite-supported Pt catalysts for oxygen reduction reactions in fuel cells

The nanoscale graphite particles were prepared and the Pt catalysts supported on such graphites were developed for oxygen reduction in the polymer electrolyte membrane fuel cells. Catalytic activity and carbon corrosion of the developed catalysts were evaluated using rotating disc electrode techniques and results were compared with those of a state-of-the-art commercial E-TEK Pt catalyst supported on carbon black Vulcan XC72. The results showed that the particle distribution and the structure of the developed Pt nanoparticles supported on the nanoscale graphite were similar to those of the commercial catalyst. The accelerated degradation testing results showed that the electrochemical active surface area losses after 1500 cycles were 46.92% and 62.2% for the developed catalyst and the commercial catalyst, respectively, while mass activity losses were 45.3% and 84.2%, respectively. The temperature-programmed oxidation results suggest that the developed catalysts had better corrosion resistance than the commercial catalyst. The developed Pt catalysts had similar catalytic performance to the commercial catalyst; however, the developed catalysts had much better corrosion resistance than the commercial catalyst. Overall, nanoscale graphite can be a promising electrocatalyst support to replace the currently used Vulcan XC72 carbon black.

Erythrocyte-like hollow carbon capsules and their application in proton exchange membrane fuel cells

Hierarchical nanostructured erythrocyte-like hollow carbon (EHC) with a hollow hemispherical macroporous core of ca. 230 nm in diameter and 30-40 nm thick mesoporous shell was synthesized and explored as a cathode catalyst support in a proton exchange membrane fuel cell (PEMFC). The morphology control of EHC was successfully achieved using solid core/mesoporous shell (SCMS) silica template and different styrene/furfuryl alcohol mixture compositions by a nanocasting method. The EHC-supported Pt (20 wt%) cathodes prepared have demonstrated markedly enhanced catalytic activity towards oxygen reduction reactions (ORRs) and greatly improved PEMFC polarization performance compared to carbon black Vulcan XC-72 (VC)-supported ones, probably due to the superb structural characteristics of the EHC such as uniform size, well-developed porosity, large specific surface area and pore volume. In particular, Pt/EHC cathodes exhibited ca. 30-60% higher ORR activity than a commercial Johnson Matthey Pt catalyst at a low catalyst loading of 0.2 mg Pt cm(-2).