首页|Coordination-induced activation of reversible Co(II)/Co(III) redox reaction in carbon nanodots/cobalt hexacyanoferrate composites with enhanced electrochemical performance
Coordination-induced activation of reversible Co(II)/Co(III) redox reaction in carbon nanodots/cobalt hexacyanoferrate composites with enhanced electrochemical performance
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NSTL
Elsevier
Cobalt hexacyanoferrate (CoHCF) as a promising cathode material of asymmetrical supercapacitors gen-erally undergoes a single redox reaction of Fe(II)/Fe(III) couple to store energy in neutral aqueous elec-trolytes. Its framework Co ions are electrochemically inactivated, leading to a limited electrochemical capacity. Herein, we develop a strategy to activate the reversible Co(II)/Co(III) redox reaction through tuning the microenvironment of Co ions. A carbon nanodots/CoHCF (C-dots/CoHCF) hybrid nanostructure has been successfully fabricated via a simple co-precipitation reaction of Co2+ and [Fe(CN)(6)](3-) ions in the presence of carboxylate-rich C-dots. Impressively, electrochemical results and X-Ray photoelectron spectroscopy (XPS) reveal the charge storage of C-dots/CoHCFs due to two-specie (Fe and Co) redox reactions, which render an enhanced electrochemical capacity. It is considered that the activation of reversible Co(II)/Co(III) redox reaction is due to the strong coordination interaction between the terminated framework Co ions and carboxylate groups of C-dots. In addition, this nanostructure offers increased active sites and promotes electron conductivity, thereby achieving a remarkable high specific capacitance (394 F g(-1) at 1 A g(-1)) and excellent rate performance. The C-dots/CoHCF cathode is paired with an activated carbon anode to assemble an aqueous asymmetrical supercapacitor, which can deliver a high energy density of 48.6 Wh kg(-1) (488 W kg(-1)) and retain 88.3% of its initial capacitance over 5000 charge/discharge cycles. (C) 2021 Elsevier B.V. All rights reserved.
NSTL
Elsevier
