Electrochemical Nitrate Reduction Reaction to Ammonia at Industrial-Level Current Densities

Abstract

The electrochemical nitrate reduction reaction (NO₃⁻RR) represents a promising green synthesis technology, enabling both resource utilization of nitrate (NO₃⁻) pollutants in wastewater and provision of a sustainable ammonia (NH₃) source for carbon neutrality. The key challenge in advancing NO₃⁻RR toward practical application lies in developing catalytic systems that maintain excellent activity, high selectivity, and long-term stability at industrial-level current densities (>300 mA cm⁻²). Although NO₃⁻RR has been developed to a certain extent, there has yet to be a comprehensive summary and analysis of the advancements in this field at industrial-level current densities up to now. This review begins with an introduction to the mechanism and theoretical basis of NO₃⁻RR, systematically summarizes and analyzes catalyst design strategies for industrial-level current densities, including alloying methods, in situ derivation strategy, heterostructure construction, doping engineering, and self-supporting electrode fabrication. In addition, the progress of industrial-level NO₃⁻RR-based electrolyzers, including flow reactor and membrane electrode assembly (MEA) technology are discussed. Meanwhile, techno–economic analysis (TEA) and life cycle assessment (LCA) are employed to investigate the economic viability and environmental impact of NO₃⁻RR, providing a comprehensive evaluation of the feasibility for large-scale application. Furthermore, the current challenges of catalytic systems under industrial electrolysis conditions are clarified, and the future development directions toward industrial-scale NH₃ synthesis are proposed, aiming to promote the value-added electrochemical conversion of pollutants and develop the industrial application of NO₃⁻RR technology.