Hansan Liu

Ultrasonic spray pyrolyzed iron-polypyrrole mesoporous spheres for fuel celloxygen reduction electrocatalysts

Pyrolyzed iron-polypyrrole mesoporous spheres have been synthesized by a template-assisted ultrasonic spray pyrolysis method, and demonstrate that high volumetric surface area is critical for improving the activity of non-noble metal catalysts towards the fuel celloxygen reduction reaction.

Temperature Dependent Performance and In Situ AC Impedance of High-Temperature PEM Fuel Cells Using the Nafion-112 Membrane

In this paper, temperature dependent performance of a Nafion 112-based proton exchange membrane (PEM) fuel cell was investigated at different temperatures, 30 psig back pressure, and 100% relative humidity (RH). High cell performance of ca. 0.637 V at 1.0 A/cm 2 was obtained at 120°C. Cell voltage decreased when the temperature increased within the range of 80-20°C. An in situ ac impedance spectroscopy method under load was developed to diagnose the performance reduction. A semi-empirical treatment was initiated to obtain expressions for extinguishing the individual performance drops caused by reaction kinetics (charge-transfer resistance), membrane resistance, and mass-transfer limitation, respectively.