[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...[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.展开更多
Iron-nitrogen-carbon(Fe-N-C)materials with Fe-N_(4)structures have been considered as the most promising alternatives of scarce and precious platinum(Pt)for oxygen reduction reaction.Particularly,the hightemperature p...Iron-nitrogen-carbon(Fe-N-C)materials with Fe-N_(4)structures have been considered as the most promising alternatives of scarce and precious platinum(Pt)for oxygen reduction reaction.Particularly,the hightemperature pyrolysis of a precursor mixture of N-containing amine polymers,Fe salts,and carbon supports,has become a popular method for the synthesis of high-performance Fe-N-C catalysts.The oxidative polymerization of amine monomers can usually proceed under acidic conditions,however,the acidcaused protonation of N-groups is not conducive to their coordination with Fe ions for the formation of high-density Fe-N_(4)sites.Here,we propose a protonation elimination strategy of soaking the polymerization products in alkaline solutions to increase Fe-N_(4)active sites.Theoretical calculations display that the Gibbs free energy change values of binding reactions between Fe ions and N-groups are-3.70 and-26.99 kcal/mol at p H 0 and 7,respectively,suggesting that the deprotonation can facilitate the Fe-N coordination.There is a two-fold increase in the number of Fe-N_(4)active sites for final Fe-N-C catalyst which exhibits significantly enhanced ORR activity and excellent Zn-air battery performance.This deprotonation effect can be applied to different amine compounds and transition-metal ions as a universal strategy for the development of preeminent non-precious metal carbon catalysts.展开更多
利用二极溅射的方法在不同衬底上沉积了Fe N O薄膜。通过扫描电子显微镜(SEM)、光电子能谱(XPS)和透射电子显微镜(TEM)等先进实验分析手段对二极溅射沉积Fe N O薄膜的形貌与结构进行了分析。XPS和TEM的结果表明,薄膜的主要成分为FeO和...利用二极溅射的方法在不同衬底上沉积了Fe N O薄膜。通过扫描电子显微镜(SEM)、光电子能谱(XPS)和透射电子显微镜(TEM)等先进实验分析手段对二极溅射沉积Fe N O薄膜的形貌与结构进行了分析。XPS和TEM的结果表明,薄膜的主要成分为FeO和少量的Fe16N2多晶体组成,生长上存在择优取向;表面均匀、致密、平整,晶粒大小在50nm左右。展开更多
文摘[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.
基金sponsored by the National Natural Science Foundation of China(No.22272105)the Natural Science Foundation of Shanghai(No.23ZR1423900)。
文摘Iron-nitrogen-carbon(Fe-N-C)materials with Fe-N_(4)structures have been considered as the most promising alternatives of scarce and precious platinum(Pt)for oxygen reduction reaction.Particularly,the hightemperature pyrolysis of a precursor mixture of N-containing amine polymers,Fe salts,and carbon supports,has become a popular method for the synthesis of high-performance Fe-N-C catalysts.The oxidative polymerization of amine monomers can usually proceed under acidic conditions,however,the acidcaused protonation of N-groups is not conducive to their coordination with Fe ions for the formation of high-density Fe-N_(4)sites.Here,we propose a protonation elimination strategy of soaking the polymerization products in alkaline solutions to increase Fe-N_(4)active sites.Theoretical calculations display that the Gibbs free energy change values of binding reactions between Fe ions and N-groups are-3.70 and-26.99 kcal/mol at p H 0 and 7,respectively,suggesting that the deprotonation can facilitate the Fe-N coordination.There is a two-fold increase in the number of Fe-N_(4)active sites for final Fe-N-C catalyst which exhibits significantly enhanced ORR activity and excellent Zn-air battery performance.This deprotonation effect can be applied to different amine compounds and transition-metal ions as a universal strategy for the development of preeminent non-precious metal carbon catalysts.
文摘利用二极溅射的方法在不同衬底上沉积了Fe N O薄膜。通过扫描电子显微镜(SEM)、光电子能谱(XPS)和透射电子显微镜(TEM)等先进实验分析手段对二极溅射沉积Fe N O薄膜的形貌与结构进行了分析。XPS和TEM的结果表明,薄膜的主要成分为FeO和少量的Fe16N2多晶体组成,生长上存在择优取向;表面均匀、致密、平整,晶粒大小在50nm左右。
