Hybrid structured CoNi2S4/Ni3S2 nanowires with multifunctional performance for hybrid capacitor electrodes and overall water splitting

Abstract

Rational design of electrode materials plays a significant role in potential applications such as energy storage and conversion. In this work, CoNi₂S₄/Ni₃S₂ nanowires grown on Ni foam were synthesized through a facile hydrothermal approach, revealing a large capacitance of 997.2 F g⁻¹ and cycling stability with 80.3% capacitance retention after 5000 cycles. The device was prepared using CoNi₂S₄/Ni₃S₂//AC as the positive electrode and active carbon as the negative electrode, and delivered an energy density of 0.4 mW h cm⁻³ at a power density of 3.99 mW cm⁻³ and an excellent cycle life with 79.2% capacitance retention after 10 000 cycles. In addition, the hybrid CoNi₂S₄/Ni₃S₂ nanowires demonstrate excellent OER performance with low overpotential of 360 mV at 30 mA cm⁻² and overpotential of 173.8 mV at −10 mA cm⁻² for the HER, a cell voltage of 1.43 V, and excellent cycle stability.