Abstract：
The electrocatalytic reduction of nitrate ions (NO3-) to nitrogen gas (N2) has emerged as an effective approach for mitigating nitrate pollution in water bodies. However, the development of efficient and highly selective cathode materials remains challenging. Conventional copper-based catalysts often exhibit low selectivity because they strongly adsorb oxygen. In this study, a straightforward solvothermal and pyrolysis method was used to grow iron-doped cobalt-copper oxide heterogeneous structures on copper foam surfaces (Fe-CoO/CuO@CF). Then, the effects of the applied potential, initial NO3- concentration, Cl- concentration, electrolyte pH, and different catalysts on the catalyst performance were investigated. Compared with recently reported congeners, Fe-CoO/CuO@CF is less expensive and exhibits outstanding activity for NO3- reduction. Meanwhile, under a cathode potential of - 1.31 V vs. Ag/AgCl, Fe-CoO/CuO@CF degrades 98.6 % of NO3- in 200 min. In addition, when employing a method inspired by NH4+ removal by breakpoint chlorination, N2 selectivity over Fe-CoO/CuO@CF was raised from 10 % without Cl- to 99.7 % when supplemented with Cl-. The catalyst demonstrated excellent cyclic stability, maintaining a high electrocatalytic activity for the conversion of NO3- to N2 gas over eleven cycles. Moreover, Fe-CoO/CuO@CF enabled 63.7 % removal of NO3- from wastewater (50 mg/L NO3--N) prepared from natural water, with 100 % conversion to N2. Computational studies showed that iron doping decreased the free energy change of the intermediate of NO3- reduction reaction. This study provides an effective strategy for the electrochemical reduction of nitrate to nitrogen gas and offers good prospects for addressing nitrate pollution.
摘要：
硝酸根离子（NO3-）电催化还原为氮气（N2）已成为减轻水体硝酸盐污染的有效途径。然而,高效和高选择性阴极材料的开发仍然具有挑战性。常规的铜基催化剂通常表现出低选择性,因为它们强烈地吸附氧。在这项研究中,使用简单的溶剂热和热解方法在泡沫铜表面（Fe-CoO/CuO@CF）上生长铁掺杂的钴铜氧化物异质结构。然后，应用潜力的影响，初始NO3-浓度,Cl-浓度,电解质pH值,并考察了不同催化剂对催化剂性能的影响。与最近报道的同类物相比，Fe-CoO/CuO@CF较便宜并且表现出优异的NO3-还原活性。同时,在-1.31V的阴极电位下Ag/AgCl,Fe-CoO/CuO@CF在200分钟内降解98.6%的NO3-。此外,当采用受断点氯化去除NH4+启发的方法时，当补充有Cl-时，N2对Fe-CoO/CuO@CF的选择性从无Cl-的10％提高到99.7％。催化剂表现出优异的循环稳定性，在十一个循环中保持对NO3-转化为N2气体的高的电催化活性。此外，Fe-CoO/CuO@CF可以从天然水中制备的废水中去除63.7％的NO3-（50mg/LNO3--N），100%转化为N2。计算研究表明，铁的掺杂降低了NO3-还原反应中间体的自由能变化。该研究为硝酸盐电化学还原为氮气提供了有效的策略，为解决硝酸盐污染提供了良好的前景。
