The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these c...The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these catalysts were buried in the carbon matrix,resulting in a low metal utilization and inaccessibility for adsorption of reactants during the catalytic process.Herein,we reported a facile synthesis based on the hard-soft acid-base(HSAB)theory to fabricate Co single-atom catalysts with highly exposed metal atoms ligated to the external pyridinic-N sites of a nitrogen-doped carbon support.Benefiting from the highly accessible Co active sites,the prepared Co−N−C SAC exhibited a superior oxygen reduction reactivity comparable to that of the commercial Pt/C catalyst,showing a high turnover frequency(TOF)of 0.93 e^(−)·s^(-1)·site^(-1)at 0.85 V vs.RHE,far exceeding those of some representative SACs with a ultra-high metal content.This work provides a rational strategy to design and prepare M−N−C single-atom catalysts featured with high site-accessibility and site-density.展开更多
化石燃料的燃烧导致大气中二氧化碳(CO_(2))的浓度迅速上升,并引发了严重的能源、环境危机。由可再生电力驱动的电催化CO_(2)还原为增值化学品和燃料是解决当前化石燃料枯竭的一种有效方法。采用“一锅法”制备了磷(P)修饰的高分散性“...化石燃料的燃烧导致大气中二氧化碳(CO_(2))的浓度迅速上升,并引发了严重的能源、环境危机。由可再生电力驱动的电催化CO_(2)还原为增值化学品和燃料是解决当前化石燃料枯竭的一种有效方法。采用“一锅法”制备了磷(P)修饰的高分散性“钴-氮-碳”(Co-N-C/P)催化剂,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)和X射线光电子能谱(XPS)等手段对催化剂的形貌、元素分布、缺陷程度、表面元素价态及配位结构进行了表征,并考察了其在H型电解槽中电催化CO_(2)还原为CO的性能。测试结果表明,所制备的Co-N-C/P催化剂在-0.9 V vs.RHE的外加电位下具有97.0%的CO法拉第效率(FE_(CO)),电流密度为4.58 mA/cm^(2),并可以进行26 h的稳定性测试。与Co-N-C催化剂相比,P的掺杂更有利于Co原子在碳黑基底上的良好分散,相应的FE_(CO)提高了约38.9%,说明P的掺杂有效提高了Co-N-C催化剂的电催化CO_(2)还原为CO的性能。展开更多
基金supported by Shanxi Province Science Foundation for Youths(202203021212300)Taiyuan University of Science and Technology Scientific Research Initial Funding(20212064)Outstanding Doctoral Award Fund in Shanxi Province(20222060).
文摘The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these catalysts were buried in the carbon matrix,resulting in a low metal utilization and inaccessibility for adsorption of reactants during the catalytic process.Herein,we reported a facile synthesis based on the hard-soft acid-base(HSAB)theory to fabricate Co single-atom catalysts with highly exposed metal atoms ligated to the external pyridinic-N sites of a nitrogen-doped carbon support.Benefiting from the highly accessible Co active sites,the prepared Co−N−C SAC exhibited a superior oxygen reduction reactivity comparable to that of the commercial Pt/C catalyst,showing a high turnover frequency(TOF)of 0.93 e^(−)·s^(-1)·site^(-1)at 0.85 V vs.RHE,far exceeding those of some representative SACs with a ultra-high metal content.This work provides a rational strategy to design and prepare M−N−C single-atom catalysts featured with high site-accessibility and site-density.
文摘化石燃料的燃烧导致大气中二氧化碳(CO_(2))的浓度迅速上升,并引发了严重的能源、环境危机。由可再生电力驱动的电催化CO_(2)还原为增值化学品和燃料是解决当前化石燃料枯竭的一种有效方法。采用“一锅法”制备了磷(P)修饰的高分散性“钴-氮-碳”(Co-N-C/P)催化剂,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)和X射线光电子能谱(XPS)等手段对催化剂的形貌、元素分布、缺陷程度、表面元素价态及配位结构进行了表征,并考察了其在H型电解槽中电催化CO_(2)还原为CO的性能。测试结果表明,所制备的Co-N-C/P催化剂在-0.9 V vs.RHE的外加电位下具有97.0%的CO法拉第效率(FE_(CO)),电流密度为4.58 mA/cm^(2),并可以进行26 h的稳定性测试。与Co-N-C催化剂相比,P的掺杂更有利于Co原子在碳黑基底上的良好分散,相应的FE_(CO)提高了约38.9%,说明P的掺杂有效提高了Co-N-C催化剂的电催化CO_(2)还原为CO的性能。
