Designing CoS2-Mo2C and CoS2-W2C hybrids for high-performance supercapacitors and hydrogen evolution reactions

Abstract

The ever-increasing obligation of green and sustainable energy has intensified rigorous research on improving efficient electrochemical energy transition and storage systems. Herein, CoS₂ prickly-pear-like sheet-intermingled metal carbide (Mo₂C and W₂C) hybrids were synthesized using a facile hydrothermal method. The fabricated hierarchical CoS₂-W₂C and CoS₂-Mo₂C hybrid structures were explored for their pseudo-capacitive behaviour by half-cell studies with specific capacities of 720 and 380 C g⁻¹ at 2 A g⁻¹, respectively, with great cycling stability. The synthesized CoS₂-W₂C and CoS₂-Mo₂C hybrid asymmetric supercapacitors demonstrated an elevated specific capacitance, reaching 423 F g⁻¹ at a current density of 2 A g⁻¹ within an extended voltage range of 1.6 V. Additionally, the highest energy density of 150 W h kg⁻¹ was achieved at a maximum power density of 4.5 kW kg⁻¹ along with a superior capacitance retention of 94.1% after 5000 cycles. As hydrogen evolution catalysts, the CoS₂-W₂C hybrid required small overpotentials of 50 and 42 mV, whereas the CoS₂-Mo₂C hybrid required 54 and 50 mV to deliver 10 mA cm⁻² current density in acid and KOH solution, respectively. This study related to metal carbide-interconnected metal sulfide provides a promising opportunity for the fabrication/design and application of multifunctional electrocatalysts.