Emerging Advances in Cu-based electrocatalysts for electrochemical nitrate reduction (NO3RR)

Nitrate is a major nitrogen-based contaminant found in water and becomes a significant threat to water resources. Nitrate accumulation is primarily attributed to unregulated human activities and industrial waste disposal. However, conventional nitrate removal technologies all have different kinds of drawbacks, hindering their degradation efficiency. Electrochemical reduction technologies have garnered substantial attention in recent years for nitrate reduction due to its eco-friendliness, extraordinary selectivity, and scale-up potential. Cu-based electrocatalysts stand out among NO3RR catalysts by having economical budget, ample storage of raw material, and superior nitrate adherence and decomposition efficiency. The electrochemical NO3RR technology has experienced vigorous development in the past decades, and a large number of research reports and review articles dedicated to electrocatalytic NO3RR have been published, showcasing the extensive research carried out in this area. In this review, we summarize the most recent developments of Cu-based electrocatalysts, including Cu-based monometallic and bimetallic materials, Cu compounds with non-zero oxidation number sites, and Cu-based hybrid materials and their derivatives. Various Cu-based catalyst systems are examined in terms of their structural characteristics and fundamental mechanism, with specific focus placed on several notable and illustrative examples. we also address the present challenges and future research interests associated with Cu-based catalysts and NO3RR in general.