High-purity hydrogen generated by the hydrolysis of sodium borohydride can be used as proton exchange membrane fuel cells (PEMFCs) for portable device applications. Because of its advantages in high storage capacity, controllable reaction, and mild condition, hydrogen generation by catalytic hydrolysis of a chemical hydride, such as sodium borohydride, has recently attracted much attention for development. Hydrogen generated by the hydrolysis of sodium borohydride using a Ru catalyst is reported in the present study. A multi-layer coating process was used on the Ru/Ni foam catalyst to enhance the cycling generation. The optimal deposition density of the Ru particle on Ni foam was confirmed by SEM morphology. The cycling generation for the steady state reaction can be maintained at least 10 times, and gradually decreases to 82% performance after the 17th cycling generation.
It was found that a combination of 20 wt% NaBH4 solution concentration and 3 wt% NaOH yields the highest performance for hydrogen generation. A hydrogen generation efficiency of 95% was obtained for a solution with a 1-g/min flow rate flowing onto the 6-cm2 area of a catalyst plate, which had a hydrogen generation rate of 0.45 L/min. As the solution flow rate was increased, the reaction efficiency decreased because of the decreased reaction time. Hydrogen fuel saturated with water generated by a NaBH4 solution shows an advantage over that from a gas cylinder for fuel cell operation. A PEM fuel cell was integrated with the hydrogen generator in the present study. The hydrogen fuel from the hydrogen generator with saturated water vapor showed a better cell performance compared with using hydrogen from a gas cylinder. Copyright © 2012 John Wiley & Sons, Ltd.