Fabrication and shape evolution of CoS2 octahedrons for application in supercapacitors

•A simple hydrothermal approach to prepare uniform CoS2 octahedrons.•The mechanism for the evolution process of the CoS2octahadrons was proposed.•The CoS2 electrode shows excellent cycling stability.

Octahedron-shaped CoS2 crystals have been successfully fabricated through a simple hydrothermal route without any surfactant or template. The well-defined octahedral structures are highly uniform with a mean edge length of ∼ 360 nm and exhibit a high geometric symmetry. The mechanism for the evolution process of the final octahedral structures is researched and proposed to begin with a growth and self-aggregation process, followed by an Ostwald ripening process. When electrochemically investigated as electrode materials for supercapacitors, the as-fabricated CoS2 electrode shows typical pseudocapative properties with a specific capacitance of 236.5 F g−1 at 1 A g−1. Remarkably, it exhibits an excellent cycling stability at 2 A g−1 with only a loss of 7.4% in the specific capacitance after 2000 cycles.