Ambient Ammonia Synthesis via Electrochemical Reduction of Nitrate Enabled by NiCo₂O₄ Nanowire Array

Abstract

NiCo₂ O₄ nanowire array on carbon cloth (NiCo₂ O₄ /CC) is proposed as a highly active electrocatalyst for ambient nitrate (NO₃ ^- ) reduction to ammonia (NH₃ ). In 0.1 m NaOH solution with 0.1 m NaNO₃ , such NiCo₂ O₄ /CC achieves a high Faradic efficiency of 99.0% and a large NH₃ yield up to 973.2 µmol h^-1 cm^-2 . The superior catalytic activity of NiCo₂ O₄ comes from its half-metal feature and optimized adsorption energy due to the existence of Ni in the crystal structure. A Zn-NO₃ ^- battery with NiCo₂ O₄ /CC cathode also shows a record-high battery performance.