Efficient Ammonia Synthesis from Nitrate Catalyzed by Au/Cu with Enhanced Adsorption Ability

The traditional method for synthesizing NH 3 is the Haber–Bosch process which results in high‐fuel consumption and environmental pollution. Therefore, ecofriendly electrochemical synthesis of NH 3 through nitrate (NO 3 − ) reduction is a good choice. Herein, an integral Au/Cu electrode to catalyze NO 3 − reduction to NH 3 is introduced. The catalyst exhibits not only the highest NH 3 yield rate (73.4 mg h −1 cm −2 ) up to now but also a very high Faradaic efficiency of 98.02% at −0.7 V at room temperature. It is commonly believed that the transformation of NO 3 − to nitrite (NO 2 − ) is an obstacle to the NH 3 generation from NO 3 − reduction. Surprisingly, unlike most of the other catalysts, Au/Cu exhibits better activity for NO 3 − reduction than that for NO 2 − reduction. Based on the detailed experimental and density functional theory calculations, the excellent performance of Au/Cu for selective NO 3 − reduction lies in the enhanced adsorption capabilities of Au/Cu to NO 3 − in the alkaline environment and the lower energy barriers of the electrochemical reduction reaction.