Issue 8, 2019

An efficient carbon-based ORR catalyst from low-temperature etching of ZIF-67 with ultra-small cobalt nanoparticles and high yield

Abstract

A facile and controllable low-temperature (450 °C) route is reported to produce ultra-small Co3O4/Co nanoparticles in nitrogen-doped hyperporous graphenic networks (Co3O4/Co@N-G-450). Firstly, a monolayer of ZIF-67 nanocrystals is directly grown in thermal-shock exfoliated graphene networks (EGO) of suitable porosity and pore-widths. Later, the ZIF-67 is etched by targeting the small concentrations of residual oxygen functionalities on EGO (≈13 atom%) under a nitrogen atmosphere at 450 °C. Therefore, the partial gasification of ZIF-67 followed by oxidation of the resultant open cobalt metal centres produces a highly active nanophase of Co3O4/Co@N-G in a mass yield of >65 wt%. The as-synthesised Co3O4/Co@N-G-450 catalyst, without any further acid washing or oxidation process, exhibits an outstanding ORR performance with a high onset (0.962 V vs. RHE) and half-wave (0.808 V vs. RHE) potential as well as limiting current density (5.2 mA cm−2) in 0.1 M KOH solution. These merits are comparable to those of commercial Pt/C and many ZIF-derived catalysts, synthesised under extended and complex chemical treatment. Moreover, the catalyst also exhibits fast reaction kinetics with a dominant 4-electron reaction pathway and high durability.

Graphical abstract: An efficient carbon-based ORR catalyst from low-temperature etching of ZIF-67 with ultra-small cobalt nanoparticles and high yield

Supplementary files

Article information

Article type
Communication
Submitted
13 11 2018
Accepted
19 12 2018
First published
30 1 2019
This article is Open Access
Creative Commons BY license

J. Mater. Chem. A, 2019,7, 3544-3551

An efficient carbon-based ORR catalyst from low-temperature etching of ZIF-67 with ultra-small cobalt nanoparticles and high yield

J. Guo, S. Gadipelli, Y. Yang, Z. Li, Y. Lu, D. J. L. Brett and Z. Guo, J. Mater. Chem. A, 2019, 7, 3544 DOI: 10.1039/C8TA10925G

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