3D CoMoO4/NiCo2Se4 networks: Micro-nano confinement effects for enhanced pseudocapacitance and water splitting

Abstract

The CoMoO₄/NiCo₂Se₄ nanocomposite, synthesized via hydrothermal and vapor deposition methods, demonstrates exceptional multifunctional performance for energy storage and electrocatalysis. As a supercapacitor electrode, it achieves a high specific capacitance of 6445.7 mF/cm² at 1 mA/cm² and retains 71.4 % capacitance after 5000 cycles, with an energy density of 753.9 μWh/cm² at a power density of 75.7 μW/cm², attributed to the synergistic effects between the CoMoO₄ and the conductive NiCo₂Se₄. Furthermore, the material exhibits outstanding bifunctional catalytic activity for alkaline water splitting, delivering low overpotentials of 270.6 mV (oxygen evolution reaction) and 177.3 mV (hydrogen evolution reaction) at 50 and 10 mA/cm², respectively, with Tafel slopes of 131.4 and 131.0 mV/dec. The cell voltage of overall water-splitting is 1.46 V (10 mA/cm²) and a high stability performance for 14 h. The CoMoO₄/NiCo₂Se₄ not only ensures efficient ion/electron transport but also creates interfacial electronic modulation through heterointerfaces, while the hierarchical nanostructure facilitates electrolyte penetration, collectively advancing energy storage capability, catalytic kinetics, and overall conversion efficiency, thereby underscoring its dual-functional superiority.