Electrochemically nitrate remediation by single-atom catalysts: advances, mechanisms, and prospects

Electrocatalytic nitrate reduction reaction (NITRR) is highly desirable for remediating nitrate (NO3-) pollution and producing ammonia (NH3) under mild conditions. To date, great efforts have been made to fabricate selective, efficient, and stable electrocatalysts for NITRR. Among the numerous strategies, single-atom catalysts (SACs) have received extensive interest and investigations due to their cost-effective and maximum atomic utilization. However, the further development of SACs-based NITRR remains hindered by a poor understanding of their in-depth mechanisms. Consequently, this review summarizes the recent advances of SACs for the NITRR, including Cu-SACs, Fe-SACs, Zn-SACs, Co-SACs, and single-atom alloys. In addition, the characterization techniques for SACs and reaction pathways of NITRR are presented to give a robust understanding of SACs-based NITRR. Finally, we analyze the current challenges in fabricating SACs for NITRR, while the key factors for further improving NITRR performances are also examined.