Plasma-Assisted Synthesis of NiSe2 Ultrathin Porous Nanosheets with Selenium Vacancies for Supercapacitor

Two-dimensional (2D) NiSe2 nanosheets with porous ultrathin structure and selenium vacancies (NiSe2 PNSvac) are synthesized via plasma-assisted dry exfoliation for supercapacitor. The specific capacitance of the NiSe2 PNSvac is 466 F g(-1) in 1 M KOH electrolyte, which is much higher than those of NiSe2 ultrathin nanosheeets (328 F g(-1)) and NiSe2 particles (251 F g(-1)). After 1000 cycles, the specific capacitance of the NiSe2 PNSvac can be well-maintained, indicating its high cycling stability. The superior performance arose from its high conductivity, short electrolyte diffusion distance, and large specific surface area.