Multifunctional 2H-TaS2 nanoflakes for efficient supercapacitors and electrocatalytic evolution of hydrogen and oxygen.

Layered transition-metal dichalcogenides based on VIB elements have attracted substantial attention for their applications in energy storage and conversion. However, few studies have concentrated on VB element dichalcogenides. Herein, we report that trifunctional 2H-TaS2 nanoflakes exhibit high performance when applied in supercapacitors, hydrogen evolution reactions (HER) and oxygen evolution reactions (OER). Notably, TaS2 nanoflakes delivered a large volumetric capacitance (502 F cm-3 at the scan rate of 10 mV s-1) and remarkable cycling stability (over 91% after 5000 cycles). TaS2 nanoflakes also exhibited remarkable catalytic performances in HER and OER processes, showing very small overpotentials and Tafel slopes, which are far better than those of the previously reported TaS2 electrocatalysts. Furthermore, TaS2 is highly stable in both alkaline and acidic electrolyte solutions. This work offers a new concept to design VB element-based electrodes for future energy storage and conversion applications.