Ambient Ammonia Synthesis via Electrochemical Reduction of Nitrate Enabled by NiCo 2 O 4 Nanowire Array

Abstract NiCo 2 O 4 nanowire array on carbon cloth (NiCo 2 O 4 /CC) is proposed as a highly active electrocatalyst for ambient nitrate (NO 3 − ) reduction to ammonia (NH 3 ). In 0.1 m NaOH solution with 0.1 m NaNO 3 , such NiCo 2 O 4 /CC achieves a high Faradic efficiency of 99.0% and a large NH 3 yield up to 973.2 µmol h −1 cm −2 . The superior catalytic activity of NiCo 2 O 4 comes from its half‐metal feature and optimized adsorption energy due to the existence of Ni in the crystal structure. A Zn‐NO 3 − battery with NiCo 2 O 4 /CC cathode also shows a record‐high battery performance.