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Facile synthesis of Rh–Sn catalysts for the electrocatalytic oxidation of ethanol is carried out via a surfactant-free microwave-assisted method. The bifunctional mechanism and electronic modification with C–C bond splitting enable this electrocatalyst to be remarkably active and durable at high fuel concentrations, which allows for a significant reduction in the volume and weight of the fuel cell system.

An anode electrode with the carbon buffer layer is fabricated to increase the performance of direct methanol fuel cell (DMFC). The carbon buffer layer is located in the middle of the anode catalyst layers, consists of porous carbon and Nafion ionomer. Since the porous and relatively hydrophilic carbon buffer layer absorbs methanol, the flux of the methanol solution in the anode electrode can be controlled. And methanol crossover is decreased by the effect of the carbon buffer layer. Consequently, methanol can be oxidized more efficiently and the performance of DMFC increases. Therefore, the membrane electrode assembly (MEA) with the carbon buffer layer on the anode electrode exhibits higher open circuit voltage (OCV) and maximum power density compared to those of conventional MEA. Especially with 3.0 M methanol solution, the maximum power density is increased by ∼60%.

Pd-based nanoparticles, such as 40 wt.% carbon-supported Pd50Pt50, Pd75Pt25, Pd90Pt10 and Pd95Pt5, for anode electrocatalyst on polymer electrolyte membrane fuel cells (PEMFCs) were synthesized by the borohydride reduction method. PdPt metal particles with a narrow size distribution were dispersed uniformly on a carbon support. The membrane electrode assembly (MEA) with Pd95Pt5/C as the anode catalyst exhibited comparable single-cell performance to that of commercial Pt/C at 0.7 V. Although the Pt loading of the anode with Pd95Pt5/C was as low as 0.02 mg cm−2, the specific power (power to mass of Pt in the MEA) of Pd95Pt5/C was higher than that of Pt/C at 0.7 V. Furthermore, the single-cell performance with Pd50Pt50/C and Pd75Pt25/C as the anode catalyst at 0.4 V was approximately 95% that of the MEA with the Pt/C catalyst. This indicated that a Pd-based catalyst that has an extremely small amount of Pt (only 5 or 50 at.%) can be replaced as an anode electrocatalyst in PEMFC.

To understand the difference in degradation characteristics between carbon-supported platinum (Pt/C) and platinum–nickel alloy (Pt1Ni1/C) cathode catalysts in membrane electrode assemblies (MEAs) of a polymer electrolyte membrane fuel cell (PEMFC), constant current operation of MEA in a single cell was conducted for 1100 h. A significant change in cell potential for the Pt1Ni1/C MEA was observed throughout the test. High-resolution transmission electron microscopy showed that sintering and detachment of metal particles in the Pt1Ni1/C catalyst occurred more sparingly than in the Pt/C catalyst. Instead, X-ray photoelectron spectroscopy element mapping revealed dissolution of Ni atoms in the Pt1Ni1 catalysts even when the Pt1Ni1/C catalyst used in the MEA was well synthesized.

A methanol-tolerant cathode electrode composed of heterogeneous composites was developed to overcome CO poisoning and large O2 mass transfer overpotential generated by methanol crossover as well as the limitation of a single alloy catalyst with methanol-tolerance in direct methanol fuel cells (DMFCs). Two additives, PtRu black and PTFE particles, were well distributed in the Pt/C matrix of the cathode electrode, and had significant effects upon open circuit voltage (OCV) and performance. A small amount of PtRu black protected the Pt surface during the oxygen reduction reaction (ORR) by decreasing CO poisoning. In addition, hydrophobic PTFE particles reduced the O2 mass transfer overpotential induced by water and permeated methanol in the cathode. Despite only 0.5 mg cm−2 of metal catalysts in the cathode, the membrane electrode assembly (MEA) with 3 M methanol showed high performance (0.117 W cm−2), which was larger than that of the traditional MEA (0.067 W cm−2).

A catalyst-coated membrane (CCM) as used in the membrane electrode assembly (MEA) of a polymer electrolyte membrane fuel cell is treated by dilute sulfuric acid solution (0.5 M) at boiling temperature for 1 h. This treatment improves the single-cell performance of the CCM without further addition of Pt catalyst. The changed microstructure and electrochemical properties of the catalyst layer are investigated by field emission scanning electron microscopy with energy dispersive X-ray, mercury intrusion porosimetry, waterdrop contact angle measurement, Fourier transform-infrared spectrometry in attenuated total reflection mode, electrochemical impedance spectroscopy, and cyclic voltammetry. The results indicate that this pretreatment enhances MEA performance by changing the microstructure of the catalyst layer and thus changing the degree of hydration, and by modifying the Pt surface, thus enhancing the oxygen reduction reaction.

Nickel hexacyanoferrate supported palladium nanoparticles are synthesized from mixtures of nickel hexacyanoferrate nanoparticles, L-ascorbic acid, and Pd(NO3)2 in EtOH (Ar, 80 °C, 3 h).

Pt/SnO2/C nanostructures with SnO2/Pt molar ratios ranging from 2.5 to 0.6 were synthesized by simple and fast microwave-assisted routes. The materials are composed of 3–5 nm SnO2 and Pt nanoparticles dispersed on the carbon support, with the morphology of the coating depending on the SnO2/Pt ratio: a homogenous layer of nanoparticles coating the carbon surface is obtained for SnO2/Pt of 2.5, whereas small Pt–SnO2 clusters are formed for lower ratios. The electrocatalytic activity of the composites on the ethanol oxidation reaction (EOR) was studied by cyclic voltammetry and chronoamperometry. All the binary catalysts exhibited lower onset potentials for the EOR and slower decay of the current density with time than a commercial Pt/C catalyst. However, improved peak current densities were only observed for the composites with ratios 1.6, 1.0 and 0.6, indicating that the formation of metal and metal oxide nanoparticles clusters is favorable for the EOR. This morphology facilitates the hydroxyl groups transfer from the metal oxide to the platinum at low potentials and also the electron transfer between carbon and platinum. The best overall performance was found for the catalyst with SnO2/Pt = 1, on which the number of three-phase boundaries is maximized. Moreover, the catalyst with SnO2/Pt = 1 continued to exhibit significantly better catalytic performance on the EOR than the commercial catalyst after potential cycling.

Synthesis of electrochemically active carbon supported nanoparticles (NPs) was achieved via direct one-step sputtering onto a carbon containing liquid substrate. Platinum (Pt) and platinum–nickel (PtNi) NPs of approximately 2 nm in size were uniformly deposited onto carbon supports via a sputtering method with polyethylene glycol (PEG) being used as a liquid substrate. Unlike expensive ionic liquids, this experiment leads to direct application for the electrocatalyst, due to the absence of the surface absorbable ions which can hinder electrochemically active surfaces. The fabricated carbon supported Pt NPs had comparable activity to commercial Pt/C catalysts, and PtNi NPs on carbon synthesized by co-sputtering exhibited 1.9 times higher mass activity at 0.95 V for the oxygen reduction reaction relative to the conventional catalyst. Synthesis via a sputtering process onto the PEG is beneficial due to repeatable results, has easy scalability for mass production as well as a simple and convenient preparation method for NPs.