One pot synthesis of nickel foam supported self-assembly of NiWO₄ and CoWO₄ nanostructures that act as high performance electrochemical capacitor electrodes

In this work, we report a facile one-step hydrothermal approach to synthesize NiWO₄ and CoWO₄ nanostructures on nickel foam as binder-free electrodes for use as supercapacitors. The as-synthesized materials showed excellent electrochemical performance, with a high specific capacitance of 797.8 F g^-1 and 764.4 F g^-1 at a current density of 1 A g^-1 after 3000 cycles. On increasing the current density by 20 times, the rate capabilities still maintained 55.6% and 50.6% of the original value for NiWO₄/Ni foam and CoWO₄/Ni foam, respectively. Moreover, both of these materials exhibited outstanding cycling stability, the 6000th cycle at 50 mV s^-1 demonstrated 2.06 and 2.81 times better capacitance than the initial cycles for NiWO₄/Ni foam and CoWO₄/Ni foam, respectively. To our knowledge, this capacitance performance is better than any previously reported value for these materials and is a consequence of the highly evolved surface area/microstructure of the materials formed by this technique.