Electrochemical Selective Nitrate Reduction: Pathways to Nitrogen and Ammonia Production

Abstract

Nitrate (NO₃ ^-) contamination from industrial, agricultural, and anthropogenic activities poses significant risks to human health and ecosystems. While traditional NO₃ ^- remediation methods are effective, they often generate secondary pollutants and incur high costs. Electrochemical NO₃ ^-reduction (ECNR) offers a sustainable alternative, converting NO₃ ^- into environmentally benign nitrogen (N₂) or valuable ammonia (NH₃). This review explores recent advancements in selective ECNR pathways for NO₃ ^--to-N₂and NO₃ ^--to-NH₃ conversion, focusing on mechanistic insights, electrocatalyst development, and optimization strategies. Key factors influencing ECNR performance, such as electrode materials, electrolyte composition, and hydrogen evolution inhibition, are discussed. Additionally, the review highlights the role of single-atom, bimetallic, and nanostructured catalysts in enhancing faradaic efficiency, total N₂ removal, and selectivity, with particular attention to Pd-Cu systems. Strategies to address challenges like low selectivity and catalyst degradation are also explored. This review underscores the potential of ECNR as a viable alternative to the energy-intensive Haber-Bosch process for NH₃ production, aligning with global sustainability goals. Finally, we identify research gaps and propose future directions for improving the efficiency, stability, and scalability of ECNR technologies.

Keywords: Ammonia (NH3) synthesis; Electrocatalysts; Electrochemical NO3− reduction; Faradic efficiency; Nitrogen (N2) production.