Incorporation of Cu-N x cofactors into graphene encapsulated Co as biomimetic electrocatalysts for efficient oxygen reduction

• Published in: Nanoscale 2018-12, Vol.10 (45), p.21076-21086
• Main Authors: Yang, Yang, Wang, Changlai, Gao, Shiqi, Mao, Kaitian, Xia, Guoliang, Lin, Zhiyu, Jiang, Peng, Hu, Lin, Chen, Qianwang
• Format: Article
• Language: English
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c8nr06538a

Unlike metals with incomplete d-shells such as Pt and Fe, copper (Cu) with a filled d-electron shell is generally regarded as a sluggish oxygen reduction reaction (ORR) electrocatalyst. However, laccase and other copper enzymes could catalyze the ORR efficiently in nature. Inspired by this, we incorporated Cu-N cofactors (Cu-N and Cu-N ) into graphene encapsulated Co frameworks by direct annealing of MOFs with a post etching process. The bioinspired electrocatalyst exhibits excellent performance and stability for ORR which is comparable to or even better than Pt/C. Meanwhile, it also illustrates a fantabulous performance in a zinc-air battery device. The excellent performance can be ascribed to the abundant atomically dispersed Cu-N cofactors in the graphene frameworks confirmed by aberration corrected HAADF-STEM and XAFS analyses. Density functional theory calculations suggest that when Cu atoms are coordinated with the surrounding N atoms, the valence electrons of Cu atoms will transfer to nitrogen atoms, simultaneously tuning the d electronic states near the Fermi level to realize fast ORR kinetics.