Self-assembled three-dimensional hierarchical CoMoO4 nanosheets on NiCo2O4 for high-performance supercapacitor

Highly regular three-dimensional (3D) NiCo2O4/CoMoO4 hierarchical nanosheets (NSs) were prepared through a simple hydrothermal process. During the hydrothermal process, ethylamine solution is crucial for the morphology of NiCo2O4/CoMoO4 NSs and self-assembled formation of CoMoO4 with porous architecture on NiCo2O4. Such curly porous hierarchical structure with large surface areas is benefit to provide numerous accessible electrochemically active sites for faradaic redox reactions. In addition, the morphologies and the mass loading adjustment of NiCo2O4/CoMoO4 NSs can be easily achieved by controlling growth time. The as-prepared NiCo2O4/CoMoO4 electrode demonstrates superior specific capacitance (1730 F/g at 1 A/g), satisfied rate capability (60%, at 20 A/g), and excellent cycling stability (76.2% capacitance retention at 10 A/g). These good electrochemical performances exhibit that the as-obtained NiCo2O4/CoMoO4 composites are efficient electrode materials for pseudo-capacitors and may provide a useful guidance for obtaining electrode materials with outstanding electrochemical performance. Highly uniform three-dimensional (3D) hierarchical porous NiCo2O4/CoMoO4 nanosheets (NSs) on Ni foam are synthesized by a simple two-step hydrothermal method. At appropriate reaction time, self-assembled porous CoMoO4 hetero-structure was formed on NiCo2O4. Such curly porous hierarchical structure with open geometry can provides large surface areas and numerous accessible channels for the electrolyte penetration and ion diffusion, and can be expected to enhance the capacitive performance of the electrode. [Display omitted] •CoMoO4 with porous structure is self-assembled on NiCo2O4.•The microstructures of composites can be controlled by tuning the growth time.•The NiCo2O4/CoMoO4 shows superior specific capacitance of 1730 F/g at 1 A/g.