Systematic design of hierarchical Ni₃S₂/MoO₂ nanostructures grown on 3D conductive substrate for high-performance pseudocapacitors

For high-performance pseudocapacitors, the rational design of nanoarchitectures has gained extensive attention to achieve superior pseudo-capacitive behaviors such as excellent energy storing ability and long-term cyclability. Here, we report systematically designed hierarchical Ni₃S₂/MoO₂ (H-Ni₃S₂/MoO₂) nanostructures directly grown on a 3D conductive substrate via a facile one-step synthesis route. The synthesized H-Ni₃S₂/MoO₂ exhibits a high specific capacitance of 1376.1 F g⁻¹ at 1 mA cm⁻², a high energy density of 45.9 Wh kg⁻¹, and a good capacitance retention of 86.0% during 2000 cycles. These enhanced pseudo-capacitive features of H-Ni₃S₂/MoO₂ are attributed to their unique nanoarchitectures favorable for pseudo-capacitive behavior as follows: (1) densely arrayed Ni₃S₂ nanoarchitectures consisting of the primary 1D nanowires and the secondary 2D nanosheets providing large electrolyte contact areas that can increase specific capacitances, and (2) well-engineered interfacial layer of MoO₂ that can induce good electrochemical cyclability. Thus, our results suggest that the H-Ni₃S₂/MoO₂ can be utilized as a promising pseudo-capacitive electrode for high-performance pseudocapacitors.