Recent Advance in Heterogenous Electrocatalysts for Highly Selective Nitrite Reduction to Ammonia Under Ambient Condition

Industrial ammonia production mainly relies on the conventional Haber-Bosch process accompanied by high energy consumption and plentiful carbon dioxide emissions, which triggered the recent interest to explore more energy-efficient and environmentally benign alternatives. Very recently, electrochemical nitrite reduction in an aqueous medium promises new opportunities for advanced, energy-efficient, and sustainable ammonia production at ambient conditions. The ammonia formation rate and Faradic efficiency are strongly associated with the adopted electrocatalysts; therefore, striving for high-efficient electrocatalysts is the key to sustainable ammonia production via the electrochemical nitrite reduction reaction. Herein, a critical overview of recent advances in electrochemical nitrite reduction reaction to ammonia is presented, highlighting the latest innovative heterogenous electrocatalysts including noble metal catalysts, transition-metal-based catalysts, and their compounds. Meanwhile, the possible reaction pathway of nitrite electroreduction to ammonia, ammonia detection, and catalytic activity descriptor are briefly summarized. Finally, the perspective and research challenges of electrocatalysts that convert nitrite to ammonia are outlined, increasing their contributions in the route of realizing a neutral carbon footprint.