Chi Kai, Wang Zhuoping, Sun Tao, He Peng, Xiao Fei, Lu Jiong, Wang Shuai
Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Department of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China.
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
Small. 2024 Aug;20(32):e2311817. doi: 10.1002/smll.202311817. Epub 2024 Mar 10.
The atomically dispersed Fe-N active site presents enormous potential for various renewable energy conversions. Despite its already remarkable catalytic performance, the local atomic microenvironment of each Fe atom can be regulated to further enhance its efficiency. Herein, a novel conceptual strategy that utilizes a simple salt-template polymerization method to simultaneously adjust the first coordination shell (Fe-NS) and second coordination shell (C-S-C, a structure similar to thiophene) of Fe-N isolated atoms is proposed. Theoretical studies suggest that this approach can redistribute charge density in the MN moiety, lowering the d-band center of the metal site. This weakens the binding of oxygenated intermediates, enhancing oxygen reduction reaction (ORR) activity when compared to only implementing coordination shell regulation. Based on the above discovery, a single Fe atom electrocatalyst with the optimal Fe-NS-S active moiety incorporated in nitrogen, sulfur co-doped graphene (Fe-SAc/NSG) is designed and synthesized. The Fe-SAc/NSG catalyst exhibits excellent alkaline ORR activity, exceeding benchmark Pt/C and most Fe-SAc ORR electrocatalysts, as well as superior stability in Zn-air battery. This work aims to pave the way for creating highly active single metal atom catalysts through the localized regulation of their atomic structure.
原子级分散的Fe-N活性位点在各种可再生能源转换方面具有巨大潜力。尽管其催化性能已经十分卓越，但每个铁原子的局部原子微环境仍可进行调控，以进一步提高其效率。在此，我们提出了一种新颖的概念策略，即利用简单的盐模板聚合法同时调节Fe-N孤立原子的第一配位层（Fe-NS）和第二配位层（C-S-C，一种类似于噻吩的结构）。理论研究表明，这种方法可以在MN部分重新分配电荷密度，降低金属位点的d带中心。这削弱了含氧中间体的结合，与仅实施配位层调控相比，增强了氧还原反应（ORR）活性。基于上述发现，设计并合成了一种在氮、硫共掺杂石墨烯中掺入最佳Fe-NS-S活性部分的单铁原子电催化剂（Fe-SAc/NSG）。Fe-SAc/NSG催化剂表现出优异的碱性ORR活性超越了基准Pt/C和大多数Fe-SAc ORR电催化剂，并且在锌空气电池中具有卓越的稳定性。这项工作旨在通过对其原子结构进行局部调控，为制备高活性单金属原子催化剂铺平道路。
