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

Abstract

Herein, a sequential pyrolysis and oxidation strategy is developed to prepare Co3O4 nanoparticles embedded in N‐doped porous carbon (Co3O4@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 Co3O4@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 Co3O4@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.

Recent progress in the syntheses and applications of multishelled hollow nanostructures

“…[127][128][129][130] Until now, carbon-based materials (such as carbon nanotubes, graphene, carbon nanofibers, hierarchically porous carbons), transition metal oxides/ sulfides/nitrides, and conducting polymers, as well as various composites of these materials, have been demonstrated to be promising electrode materials for use in supercapacitors. [131][132][133][134][135][136][137][138][139] Considering their superior environmental compatibility, specific capacitance, and cost-effectiveness, some transition metal oxides, such as copper oxide, iron oxide, nickel oxide, cobalt oxide, and manganese oxide, have been widely investigated as supercapacitor electrode materials. [140][141][142][143][144][145][146][147] In order to improve the amount of electrochemically active sites, enhance electron and ion conductivities, as well as inhibit the dissolution of active species into the electrolytes, various hollow metal oxide nanostructures have been preferred.…”

Recent Progress in Co3O4‐Based Nanomaterials for Supercapacitors

“…Because of the synergistic action of ZIF‐67 and ZIF‐8, the electrode forms a material with high specific surface area and high activity. It has excellent electrochemical performance (as shown in Figure 21bc), specific capacitance of 422.8 F/g when the current density is 1 A/g, good ratio capacity (256 F/g when the current density is 5 A/g) and excellent cycle stability (capacity retention rate is 87.9% after 5000 cycles) [153] . Han et al.…”

“…It has excellent electrochemical performance (as shown in Figure 21bc), specific capacitance of 422.8 F/g when the current density is 1 A/g, good ratio capacity (256 F/g when the current density is 5 A/g) and excellent cycle stability (capacity retention rate is 87.9% after 5000 cycles). [153] Han et al used melamine foam as raw material to synthesize 3D macroporous carbon sponge structures (MCS) after heat treatment. Co 3 O 4 nanoparticles from ZIF-67 heat treatment were uniformly distributed on MCS, and Co 3 O 4 /MCS nanocomposites were prepared (Figure 21d).…”

Salt-assisted synthesis of advanced carbon-based materials for energy-related applications

“…139 Similar results are also observed in many other systems. [140][141][142][143] Additionally, XPS analysis revealed that the N doping amount in the resultant N-PCNs reached 6.55 wt%. This high doping level is much higher than conventional ones.…”