Features	Description
High electrocatalytic activity	Because of its exceptional electrocatalytic activity, Cu is crucial in converting nitrate to ammonia. Cu’s superior electron-transfer properties are responsible for its extraordinary ability since it facilitates the reduction of nitrate ions to ammonia at the cathode of an electrochemical cell [86] [90] [91] .
Tunability of surface properties	Scientists try to improve the efficiency of Cu catalysts by tweaking their surface properties. Several factors, including surface area, crystallinity, and oxidation state, are carefully controlled to maximize the efficiency and selectivity of the catalyst throughout the nitrate reduction process. Such improvements greatly boost the process’s overall efficiency and open the door to future developments [92] .
Catalyst stability	Cu catalysts exhibit good stability during the reduction process, allowing for continuous and long-term operation. However, stability is affected by factors such as pH, temperature, and the presence of interfering species, and ongoing research aims to improve catalyst durability [93] .
Selectivity control	The selectivity of copper catalysts in the electrochemical reduction of nitrate is influenced by adjusting reaction conditions and surface properties. By carefully controlling the reaction parameters, researchers enhance the selectivity towards ammonia production, minimizing the formation of undesired by-products [94] .
Nanomaterials and nanostructured catalysts	Cu nanoparticles and nanomaterials have demonstrated enhanced catalytic activity due to their high surface area and unique electronic properties. Nanostructured copper catalysts offer improved electron transfer and efficiency, leading to higher ammonia yields and reduced energy consumption [95] .
Synergistic effects	Cu catalysts are combined with other materials, such as carbon-based nanomaterials or metal oxides, to create composite catalysts with synergistic effects. These composite materials often exhibit improved catalytic performance, providing opportunities for further optimization in nitrate reduction reactions [96] .
Electrochemical response	Cu catalysts display distinctive electrochemical responses during nitrate reduction, allowing for facile monitoring and optimization of their catalytic performance through electrochemical techniques [97] .