Electronically and Geometrically Modified Single-Atom Fe Sites by Adjacent Fe NPs for Enhanced Oxygen Reduction.
Fe-N-C materials exhibit excellent activity and stability for oxygen reduction reaction (ORR), as one of the most promising candidates to replace the commercial Pt/C catalysts. However, it is challenging to unravel the features of the superior ORR activity originated from Fe-N-C materials. In this work, the correlations between the electronic and geometric structures about the isolated Fe-N-C sites including the corresponding ORR activities are investigated by varying the secondary thermal activation temperature of a rationally designed NC-supported Fe single-atom catalyst (SAC). The systematic analyses demonstrate the significant role of coordinated atoms of SA and metallic Fe nanoparticles (NPs) in altering the electronic structure of isolated Fe-N-C sites. Meanwhile, the strong interaction between isolated Fe-N-C sites and adjacent Fe NPs can change the geometric structure of isolated Fe-N-C sites. Theoretical calculations reveal that optimal regulation of the electronic and geometric structure of isolated Fe-N-C sites by the co-existence of Fe NPs narrows the energy barriers of the rate-limiting steps of ORR, resulting in outstanding ORR performance. This work not only provides the fundamental understanding of the underlying structure-activity relationship, but also sheds light on designing efficient Fe-N-C catalysts. This article is protected by copyright. All rights reserved.
['Zhao|Shu-Na|SN|', 'Li|Jun-Kang|JK|', 'Wang|Rui|R|', 'Cai|Jinmeng|J|', 'Zang|Shuang-Quan|SQ|https://orcid.org/0000-0002-6728-0559']
oxygen reduction reaction Fe nanoparticles atomic Fe-N(O)x sites electronic modification geometric modification