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For supercapacitor electrode material, hydrous RuO 2 /carbon black nanocomposites were prepared by the novel incipient wetness method using a fumed silica nanoparticle. First, hydrous RuO 2 /fumed silica/Ketjen black ͑KB͒ was synthesized by the sol-gelbased method. After dissolving the fumed silica, the hydrous RuO 2 /KB nanocomposite, which is composed of RuO 2 nanoparticles ͑20-60 nm͒ dispersed on the high-surface-area KB ͑1180 m 2 g −1 ͒, was formed with 3D porous structure at high loading of 60 wt % RuO 2 ͑Ru content is 46 wt %͒. The hydrous RuO 2 /KB nanocomposite electrode exhibited a specific capacitance of 647 F g −1 with high charge utilization of RuO 2 ͑72%͒, which is significantly higher than reported values by other workers at similar loading of RuO 2 . The high capacitance and the high charge utilization were probably due to enhanced proton paths within the 3D porous structure of the nanocomposite materials.

The design of highly durable, electroactive, and cost-effective catalysts to replace the currently prevalent Pt-based ones has long been a major milestone for expanding the market penetration of fuel cell electric vehicles (FCEVs). Over the past decades, catalyst degradation in automotive fuel cells under transient conditions (e.g., startup/shutdown and cell reversal) has attracted much attention due to its irreversible consequences for the membrane electrode assembly (MEA). Herein, we evaluate IrRu n /C as alternative catalysts to increase MEA anode durability under cell reversal conditions and investigate their suitability for use in FCEVs. Among the various Ir:Ru ratios, the best hydrogen oxidation activity was observed for Ir:Ru = 1:4 (mol/mol), as confirmed by rotating disk electrode measurements. The performances of IrRu 4 /C and Pt/C as anode catalysts were compared side by side, with the corresponding I-V and anode polarization tests carried out under various operating conditions (cell temperature, relative humidity, and backpressure). Importantly, IrRu 4 /C showed Pt-comparable (∼100%) MEA performance and hydrogen oxidation activity, additionally exhibiting a ∼120 times better durability under cell reversal conditions.

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The performance of macrocyclic catalysts in oxygen reduction was investigated for a direct methanol fuel cell. The dependence of catalytic activity on different factors was determined for two classes of precursors; namely, iron porphyrin (Fe-PC) and iron phthalocyanine (Fe-TPP). It was found that there was an optimal heattreating temperature for each precursor. Heat-treated Fe-TPP shows maximum activity at 750°C, while the highest performance in the case of Fe-PC is observed at 500°C. It was shown that oxygen reduction activity is affected by the number of nitrogen bonds formed with iron, particle size, and formation of carbon layers.

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