Composites of NiSe₂ Nanosheets on CoMoO₄ Nanomaterials as Electrodes for Supercapacitors

In this study, CoMoO 4 /NiSe 2 composite electrode materials were prepared using a two-step hydrothermal method followed by vapor deposition, with comprehensive structural and electrochemical characterizations performed. The CoMoO 4 /NiSe 2 composite, combining the excellent cycling performance of CoMoO 4 and the good conductivity of NiSe 2, demonstrated outstanding electrochemical performance. Morphologically, the composite exhibited a nanosphere structure with spiky protrusions, where nanoballs were covered by nanosheets. Electrochemical tests showed that the CoMoO 4 /NiSe 2 composite electrode achieved a specific capacitance of 2352.9 mF/cm 2 at 1 mA/cm 2 . Assembled into an asymmetric supercapacitor, it exhibited an energy density of 39.7 μWh/cm 2 and a power density of 701.0 μW/cm 2 . In oxygen evolution reaction tests, the composite material showed an overpotential of 303.6 mV at 50 mA/cm 2 . In hydrogen evolution reaction tests, it exhibited an overpotential of 203.6 mV at 10 mA/cm 2 and an electrolysis voltage of 1.86 V at 50 mA/cm 2 . The results demonstrate that the CoMoO 4 /NiSe 2 composite electrode material possesses high specific capacitance and excellent rate performance in supercapacitors, along with low overpotential and high stability in electrocatalytic reactions, indicating its broad application prospects in energy storage and conversion devices.