O‐, N‐Atoms‐Coordinated Mn Cofactors within a Graphene Framework as Bioinspired Oxygen Reduction Reaction Electrocatalysts

• Published in: Advanced materials (Weinheim) 2018-07, Vol.30 (28), p.e1801732-n/a
• Main Authors: Yang, Yang, Mao, Kaitian, Gao, Shiqi, Huang, Hao, Xia, Guoliang, Lin, Zhiyu, Jiang, Peng, Wang, Changlai, Wang, Hui, Chen, Qianwang
• Format: Article
• Language: English
• Subjects: bioinspiration; Biological evolution; Biomimetics; Catalysis; Catalytic activity; Chemical reactions; Dispersion; electrocatalysis; Electrocatalysts; Electron states; Graphene; Graphite - chemistry; Iron; Manganese; Materials science; Metal air batteries; metal–organic frameworks; Nitrogen; Oxidation-Reduction; Oxygen; Oxygen reduction reactions; Reaction kinetics; single atoms; Transition metals; Tuning; Zinc-oxygen batteries
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201801732

Manganese (Mn) is generally regarded as not being sufficiently active for the oxygen reduction reaction (ORR) compared to other transition metals such as Fe and Co. However, in biology, manganese‐containing enzymes can catalyze oxygen‐evolving reactions efficiently with a relative low onset potential. Here, atomically dispersed O and N atoms coordinated Mn active sites are incorporated within graphene frameworks to emulate both the structure and function of Mn cofactors in heme–copper oxidases superfamily. Unlike previous single‐metal catalysts with general M‐N‐C structures, here, it is proved that a coordinated O atom can also play a significant role in tuning the intrinsic catalytic activities of transition metals. The biomimetic electrocatalyst exhibits superior performance for the ORR and zinc–air batteries under alkaline conditions, which is even better than that of commercial Pt/C. The excellent performance can be ascribed to the abundant atomically dispersed Mn cofactors in the graphene frameworks, confirmed by various characterization methods. Theoretical calculations reveal that the intrinsic catalytic activity of metal Mn can be significantly improved via changing local geometry of nearest coordinated O and N atoms. Especially, graphene frameworks containing the Mn‐N3O1 cofactor demonstrate the fastest ORR kinetics due to the tuning of the d electronic states to a reasonable state. Atomically dispersed O‐ and N‐atoms‐coordinated Mn active sites (especially Mn‐N3O1) are incorporated within graphene frameworks to emulate both the structure and function of Mn cofactors in the heme–copper oxidase superfamily, which exhibit excellent activity for the oxygen reduction reaction (onset potential 0.94, half‐wave potential 0.86 V) and zinc–air battery performance, superior to even that of commercial 20 wt% Pt/C.