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Summary: In the purpose of maximizing the utilization of noble metal Pt in oxygen reduction catalysts, we illustrate a synthesis method of preparing the low‐platinum PtNi/C alloyed oxygen reduction reaction (ORR) catalyst, which is developed through the H2‐induced treatment to a glucose reduced PtNi/C alloy. After post‐treatment with H2/N2 mixture gases, this catalyst displays excellent ORR catalytic activity and durability for the synergetic influences of electronic and geometry effects on catalysts during the alloying. Specifically, the as‐prepared PtNi/C (350°C‐6 h) sample delivers preponderant ORR activity with only 53.5% Pt usage than the commercial Pt/C. The specific activity and mass activity are corresponding 7.49 times and 3.5 times to the commercial Pt/C. This catalyst exhibits excellent ORR catalytic activity after 10 000 potential cycles in acid, which benefits from the well alloyed core‐shell structure of PtNi/C. H2‐induced thermal treatment has significant effects on the development of high performance low‐platinum PtNi/C alloy catalyst, and plays the significant role in the formation of well‐alloyed core‐shell structures. The lowered d‐band center is believed to facilitate ORR catalysis through weakening the adsorption of intermediate oxygen species on the alloyed Pt surface. Therefore, PtNi/C(350°C‐6 h) alloyed catalyst possesses outstanding ORR catalytic activity with much lower Pt loading. [ABSTRACT FROM AUTHOR]

Low-temperature solid oxide fuel cell (SOFC, 300-600°C) technology fueled by methanol possessing significant importance and application in polygenerations has been developed. Thermodynamic analysis of methanol gas-phase compositions and carbon formation indicates that direct operation on methanol between 450 and 600°C may result in significant carbon deposition. A water steam/methanol ratio of 1/1 can completely suppress carbon formation in the same time enrich H production composition. Fuel cells were fabricated using ceria-carbonate composite electrolytes and examined at 450-600°C. The maximum power density of 603 and 431 mW cm was achieved at 600 and 500°C, respectively, using water steam/methanol with the ratio of 1/1 and ambient air as fuel and oxidant. These results provide great potential for development of the direct methanol low-temperature SOFC for polygenerations. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Pinholes in the membrane electrode assembly (MEA) of a fuel cell can lead to premature fuel cell failure. The main causes for pinhole formation are contaminant particles, non-uniform stress distribution, and membrane corrosion. In this paper fuel cell performance is compared before and after piercing the MEA with a pin to introduce a pinhole. Experiments revealed that under some operation conditions, the presence of a pinhole did not immediately impact performance. This implies that fuel cell engineers might overlook pinhole damage in its initial stages. However, durability testing shows that the performance of a fuel cell with a pinhole declines faster than that of a fuel cell with an intact MEA. During open circuit voltage measurement, a substantial voltage drop is observed for the fuel cell with a pinhole in the MEA. Simulation results point to the formation of a hot spot in the cathode catalyst layer of the fuel cell at the site of the pinhole. The temperature of the hotspot is 4∼5 K higher than the surrounding area, which is not so high as to impair performance. This explains the steady operation of the fuel cell over a 40-hour run cycle. This study identifies increasing anode pressure as a method for pinhole detection in fuel cell stacks. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Nanostructured Ce0.8Sm0.2O1.9 (SDC) is investigated for low-temperature solid oxide fuel cells based on SDC- 30 wt% (53 mol% Li2CO3:47 mol% Na2CO3) composite electrolyte in this work. SDC is prepared by the combined citrate and EDTA complexing method. X-ray powder diffraction shows that it forms a well-cubic fluorite structure after being sintered at 700°C for 2 h. The particle is about 12 nm detected by the transmission electron microscopy. Conductivity for the composite is much higher than the pure SDC at comparable temperatures. A transition of ionic conductivity occurs at 450°C for the composite electrolyte. The single cells are fabricated by a simple dry-pressing process and tested at 450–600°C. A maximum power density of 900 mW cm-2 and the open-circuit voltage of 0.92 V are achieved at 600°C. The conduction mechanism has been discussed by comparing the conductivity of composite electrolyte under different conditions. AC impedance for single cell indicates that the electrochemical process involving cathode and anode reactions is the rate-limiting step. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]