Preparation of hierarchical mesoporous Co₃O₄ bundle using [Bmim]TA as a multi-role starting material and its supercapacitor application

Abstract

Hierarchical mesoporous Co₃O₄ bundles were obtained by a hydrothermal method combined with a subsequent calcination treatment. During the synthesis of the precursor Co₂(OH)₂CO₃, the versatile ionic liquid 1-butyl-3-methylimidazolium trifluoroacetate performed three roles as the co-solvent, precursor, and template. A supercapacitor based on the as-prepared Co₃O₄ was fabricated and further evaluated by cyclic voltammetry and chronopotentiometry measurements, which exhibited a specific capacitance of 357 F g⁻¹ at 2 A g⁻¹ after 500 cycles under high loading conditions (approximately 8 mg cm⁻²). Moreover, the mesoporous Co₃O₄ was found to maintain 85.5 % specific capacitance with an increase in the current density from 1 to 20 A g⁻¹; this behavior was attributed to the unique structure of the bundles which allowed most of the Co₃O₄ sheets to efficiently participate in the electrochemical reaction.

Graphical abstract