Hybrid structured CoNi(2)S(4)/Ni(3)S(2) nanowires with multifunctional performance for hybrid capacitor electrodes and overall water splitting

Rational design of electrode materials plays a significant role in potential applications such as energy storage and conversion. In this work, CoNi(2)S(4)/Ni(3)S(2) 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 CoNi(2)S(4)/Ni(3)S(2)//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 CoNi(2)S(4)/Ni(3)S(2) 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.