Cobalt Oxide Nanoparticles Embedded in N-Doped Porous Carbon as an Efficient Electrode for Supercapacitor

Herein, a sequential pyrolysis and oxidation strategy is developed to prepare Co 3 O 4 nanoparticles embedded in N-doped porous carbon (Co 3 O 4 @N-pC) using a bimetal zeolitic imidazolate framework (ZIF-67@ZIF-8) as precursors, which is first obtained via a simple wet-chemical process. The electrochemical performances of Co 3 O 4 @N-pC, ZIF-67@ZIF-8 precursors, and Co@N-Pc intermediates (the direct pyrolysis products from ZIF-67@ZIF-8) are studied as supercapacitor electrodes in comparison. The results reveal that the specific capacitance of the optimized Co 3 O 4 @N-pC electrode can reach up to 422.8 F g −1 at 1 A g −1 with a good rate capability (256 F g −1 at 5 A g −1 ) and excellent long-term cycling stability (87.9% retention after 5000 cycles). Such performance is superior over ZIF-67@ZIF-8 precursors (232 F g −1 at 1 A g −1 , 168.9 F g −1 at 5 A g −1 , and 82.7% retained after 5000 cycles) and Co@N-pC intermediates (218.4 F g −1 at 1 A g −1 , 171 F g −1 at 5 A g −1 , and 76.3% retained after 5000 cycles). The findings in this work are expected to provide a new avenue to explore other metal oxide/carbon materials for various applications.