Fe-N-C单原子催化剂电催化亚硝酸盐制氨  

Electrocatalytic synthesis of ammonia from nitrite over Fe-N-C single-atom catalyst

作　　者：王雪佳 杨级 蒋远 董金超 李剑锋[2] WANG Xuejia;YANG Ji;JIANG Yuan;DONG Jinchao;LI Jianfeng(College of Energy,Xiamen University,Xiamen 361102,China;College of Chemistry and Chemical Engineering,Xiamen University,Xiamen 361005,China)

机构地区：[1]厦门大学能源学院,福建厦门361102 [2]厦门大学化学化工学院,福建厦门361005

出　　处：《厦门大学学报(自然科学版)》2025年第1期128-136,共9页Journal of Xiamen University:Natural Science

摘　　要：[目的]为进一步拓展单原子催化剂在亚硝酸盐还原制氨领域的应用,提出了一种铁-氮-碳(Fe-N-C)单原子催化剂电催化亚硝酸盐还原制氨的新体系.[方法]以二氧化硅为硬模板,2,6-二氨基吡啶为碳氮前驱体,硝酸铁为金属盐,通过“热解-刻蚀”策略制备了Fe-N-C单原子催化剂,并将其应用于亚硝酸盐制氨反应.[结果]多种结构表征结果显示,Fe-N-C催化剂表面的Fe物种呈现高度分散特征并以单原子形式存在.此外,Fe物种的化学环境主要是+2和+3价混合态,且通过与4个吡啶氮配位而稳定存在,即Fe-N-C催化剂的金属中心微观配位环境为Fe-N4结构.与纯氮碳(N-C)载体相比,本研究制备的Fe-N-C催化剂具有优异的亚硝酸盐还原性能,不仅表现出更高的起始还原电位(0 V vs可逆氢电极),具有接近100%的产氨法拉第效率和高的氨产率[8.4 mg/(h·cm^(2))],并且在连续20次催化循环测试中显示出优异的催化稳定性.[结论]本研究制备的Fe-N-C单原子催化剂对亚硝酸盐还原制氨具有优异的电催化活性,其高活性可能来源于对NO_(2)^(-)的显著吸附,并进一步促进活性氢参与脱氧加氢过程.该Fe-N-C单原子催化亚硝酸盐还原体系可为后续合成氨的活性中心设计提供指导方向.[Objective]The synthesis of ammonia under electrochemical mild conditions is considered a promising alternative to the conventional Haber-Bosch method.However,the reduction of nitrite,an important nitrogen-containing precursor,to ammonia has rarely been reported in the field of single-atom catalysis.To expand research in this field,this study developed a new system for the reduction of nitrite to ammonia catalyzed by iron-nitrogen-carbon(Fe-N-C)single-atom catalyst.[Methods]The Fe-N-C single-atom catalyst was synthesized using a pyrolysis-etching strategy with silica as a hard template,2,6-diaminopyridine as a carbon-nitrogen precursor,and ferric nitrate as a metal salt.The synthesized catalyst was further analyzed using X-ray diffraction(XRD),scanning transmission electron microscopy(STEM),and high angular annular dark-field(HAADF)-STEM to determine the metal center dispersion.Moreover,the microscopic coordination environment of the iron center was determined using X-ray photoelectron spectroscopy(XPS)and X-ray absorption spectroscopy(XAS).The Fe-N-C single-atom catalyst was then used for the electrocatalytic synthesis of ammonia from nitrites.To prepare the Fe-N-C catalyst,3 mL 40%(by mass)silica solution was mixed with 400 mL ultrapure water.Then,5.45 g 2,6-diaminopyridine was added and stirred at room temperature for 30 min.The mixture was then placed in an ice bath for 30 min,after which 1 g sodium hydroxide was added,and stirring continued for another 30 min.Next,17.13 g ammonium persulfate was dissolved in 100 mL ultrapure water by stirring until the solids were completely dissolved.The ammonium persulfate solution was added to the above mixture at once,stirred rapidly for 8 min,and then stirred at normal rate in an ice bath for 12 h.The resulting mixture was extracted and filtered under reduced pressure,with a large amount of water until the filtrate was neutral,and was placed in an oven at 80℃for sufficient drying to obtain a nitrogen-carbon coated silica polymer,noted as SiO_(2)@PDAP-3 mL.Next,an appr

关 键 词：Fe-N-C单原子催化剂 电催化 亚硝酸盐还原 合成氨 

分 类 号：O643.36[理学—物理化学]