Electroreduction of nitrate to ammonia in alkaline solutions using hydrogen storage alloy cathodes

The galvanostatic and potentiostatic electrolysis of nitrate was carried out in alkaline solution using three types of hydrogen storage alloy electrodes. Ammonia was produced and its current efficiency was influenced by a series of factors, such as nitrate concentration, type of electrode and its initial state, applied current and potentials. The electrolysis on the fully hydrided electrode in the 0.5 M KOH + 0.05 M KNO3 solution produced ammonia with a current efficiency of 90% at -1.2 V versus SCE. It was found that the dissolved hydrogen atom in the alloy electrode could directly participate in the reduction process and enhance the catalytic activity of the electrode. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.