Effects of organic acid catalysts on the hydrogen generation from NaBH₄

Sodium borohydride has received much attention from fuel cell developers due to its high hydrogen storage capacity. In this study, organic acid solutions such as malic, citric, acetic acids were successfully utilized to accelerate and control hydrogen generation from stabilized sodium borohydride solutions. The generated hydrogen by malic acid was then continuously supplied to a PEMFC single cell. A power density of 168 mW cm^-2 was achieved with a hydrogen flow rate of 0.050 L min^-1 that was generated by adding 10 wt% aqueous malic acid to the stabilized sodium borohydride solution at an air flow rate of 0.11 L min^-1 without humidification. Further increase of power density to 366 mW cm^-2 is practicable by maintaining a precise hydrogen flow rate of 0.3 L min^-1. The current study focuses on the development of an instant hydrogen generation method for micro fuel cell applications. We successfully demonstrated that fast and direct generation of hydrogen could be achieved from stabilized borohydride using inexpensive organic acid solutions rather than expensive metal catalysts and a PEMFC single cell could be operated by generated hydrogen.