Hydrogen generation system using sodium borohydride for operation of a 400 W-scale polymer electrolyte fuel cell stack

Sodium borohydride (NaBH4) in the presence of sodium hydroxide as a stabilizer is a hydrogen generation source with high hydrogen storage efficiency and stability. It generates hydrogen by self-hydrolysis in aqueous solution. In this work, a Co-B catalyst is prepared on a porous nickel foam support and a system is assembled that can uniformly supply hydrogen at > 6.5 L min(-1) for 120 min for driving 400-W polymer electrolyte membrane fuel cells (PEMFCs). For optimization of the system, several experimental conditions were changed and their effect investigated. If the concentration of NaBH4 in aqueous solution is increased, the hydrogen generation rate increases, but a high concentration of NaBH4 causes the hydrogen generation rate to decrease because of increased solution viscosity. The hydrogen generation rate is also enhanced when the flow rate of the solution is increased. An integrated system is used to supply hydrogen to a PEMFCs stack, and about 465 W power is produced at a constant loading of 30 A. (c) 2007 Elsevier B.V. All rights reserved.