Hydrogen generation from solid NaBH 4 with catalytic solution for planar air-breathing proton exchange membrane fuel cells

Abstract

In the pursuit of the development of alternative mobile power sources with high energy densities, this study elucidated a new hydrogen generation approach from solid NaBH 4 using a new catalyst, sodium hydrogen carbonate (NaHCO 3), which was placed in a small and compact cartridge. A planar air-breathing PEMFC system fitted with the cartridge has been investigated for testing hydrogen generation from NaBH 4 and NaHCO 3. NaHCO 3 allowed the hydrogen cartridge to control hydrogen generation and to improve the power density, fuel efficiency, energy efficiency, and cell response. The cell performance of solid NaBH 4 air-breathing PEMFC system strongly depended on the operating conditions: the feeding rates and concentrations of catalytic solutions for NaBH 4 hydrolysis. In various concentrations (5 - 12 wt %) of NaHCO 3 aqueous solutions, 10 wt % NaHCO 3 aqueous solution exhibited the highest maximum power density of 128 mW cm −2 at 0.7 V, which was estimated to be a Faradic efficiency of 78.4% and an energy efficiency of 46.3%. The data illustrated that NaHCO 3 was an effective catalyst for hydrogen generation with the solid NaBH 4, which is considered as a hydrogen carrier for air-breathing micro PEMFCs operated without auxiliary hydrogen controller or devices.