Development of a direct ammonia-fueled molten hydroxide fuel cell

A fundamental study on direct ammonia fuel cells with a molten hydroxide electrolyte was conducted. The electrochemical oxidation of ammonia on Pt electrode in a molten NaOH-KOH electrolyte was investigated by cyclic voltammetry and mass spectrometry. Ammonia was proved to be oxidized to N2 on the Pt electrode during anodic polarization in the molten hydroxide electrolyte. Furthermore, the direct ammonia fuel cell, i.e., Pt gas diffusion electrode|molten NaOH-KOH electrolyte|Pt gas diffusion electrode, was assembled and operated at 200-220 °C. The cell achieved the maximum power density of ca. 16 mW cm−2 at 220 °C with the supply of NH3 and humidified O2 to the anode and cathode, respectively. The mechanism of ammonia oxidation over Pt electrodes in a molten hydroxide electrolyte was discussed based on the results obtained.