Holey C@ZnFe₂O₄ Nanoflakes by Carbon Soot Layer Blasting Approach for High Performance Supercapacitors

Holey nanomaterials have been explored as superior electrode materials for energy storage devices. However, the existing methods for synthesis of holey materials are often too complicated and are limited mainly to graphene-derived holey 2D nanosheets. Herein, we report for the first time a versatile, efficient, and low-cost camphor carbon soot layer blasting approach for the generation of nanoholes in C@ZnFe₂O₄ nanoflakes without damaging the original nanoflake morphology. In the three-electrode system, the holey C@ZnFe₂O₄ nanoflake based electrode exhibits a high specific capacitance of 1452 F g^-1 at 1 A g^-1 and excellent cyclic stability with 96% of capacitance retention over 50 000 cycles in 6 M KOH electrolyte. In addition, a symmetric supercapacitor fabricated using two holey C@ZnFe₂O₄ nanoflake electrodes with [EMIM][BF₄] electrolyte exhibits high capacitance (190 F g^-1 at 1 A g^-1), high energy density (81.4 Wh kg^-1 at power density of 0.87 kW kg^-1), and superlong cyclic stability (96% retention over 50 000 cycles), which indicates the excellent stability of holey C@ZnFe₂O₄ nanoflakes in ionic liquid. The carbon soot layer blasting approach developed herein is also extendable for other nanostructures obtained from different metal oxides and sulfides. Thus, the present work provides a significant advancement in synthesis of holey nanomaterials for high-performance energy storage devices.