Facile synthesis of NiO@Ni(OH)₂-α-MoO₃ nanocomposite for enhanced solid-state symmetric supercapacitor application

Electrochemical supercapacitor fabrication using heterogeneous nanocomposite is one of the most promising pathways for energy storage technology. Herein, heterostructure based nickel-molybdenum (NiO@Ni(OH)₂-α-MoO₃) nanocomposites have been successfully prepared on nickel foil via hydrothermal route for supercapacitor application. The mixed phases of cubic, hexagonal, and orthorhombic crystal structure for NiO, Ni(OH)₂, and α-MoO₃, respectively were observed by X-ray diffraction. Heterostructures of nanosheet and nanosphere morphologies were confirmed by high resolution transmission electron microscopy. Impressively, the NiO@Ni(OH)₂-α-MoO₃ composite working electrode exhibits a high specific capacitance of 445 Fg^-1 at current density of 1 Ag^-1 and shows outstanding rate capability (97.3% capacity retention after 3000 cycles at 10 Ag^-1), compared to that of NiO@Ni(OH)₂ nanoparticles. Notably, two-electrode symmetric supercapacitor of NiO@Ni(OH)₂-α-MoO₃ working electrode shows a high specific capacitance of 172 Fg^-1 at 0.5 Ag^-1, excellent rate capability and good cycling stability. Also, an excellent cycling stability (capacity retention of 98% after 5000 cycles) is observed for NiO@Ni(OH)₂-α-MoO₃ as a working electrode in the symmetric two-electrode system. The obtained attractive results demonstrate that nanocomposite anode material can be used for development of a wide-range of energy storage devices.