Design Strategies to Enhance Copper Electrocatalytic Performance for Nitrate-to-Ammonia Electroreduction

Electrochemical nitrate reduction (NO3−RR) is being recognized as a sustainable approach to synthesizing ammonia which is essential for the chemical industry and a key agricultural input conventionally produced through the hard-to-abate Haber Bosch process. Among various transition metals, copper-based electrocatalysts stand out in efficaciously carrying out this reaction owing to their superior electrocatalytic activity and selectivity. In this context, here, current state of research and advanced scientific understandings of employing Copper for NO₃−RR are succinctly, but comprehensively, presented while focusing on its design strategies to enhance the electrocatalytic performance. First, the NO3−RR reaction mechanisms taking place at the surface of copper are described, followed by a discussion of its unique attributes in facilitating ammonia electrosynthesis. Then, various electrocatalyst fabrication routes and designing strategies are reviewed, emphasizing the role of the evolved structure, morphology, textural properties and surface chemistries in improving the reaction kinetics. Nanostructuring, facet and defect engineering, support, doping, alloying, heterojunction and the role of single active catalysts (SACs) centers as the key parameters for enhanced electrocatalytic behavior are highlighted.