Multi-compositional hierarchical nanostructured Ni3S2@MoSx/NiO electrodes for enhanced electrocatalytic hydrogen generation and energy storage

Rational design of multi-compositional hierarchical nanostructures from earth-abundant materials holds great potential in the fields of electrocatalytic hydrogen evolution and supercapacitive energy storage. However, such nanostructures often require multi-step synthesis routes which are rather elaborate. In this study, we demonstrate a facile synthesis route to attain hierarchical nanostructures comprised of multiple constituents with varied geometric dimensionality, i.e. NiO nanoparticles incorporated in two-dimensional (2D) sulfurized molybdenum-based nanosheets coated on a one-dimensional (1D) Ni3S2 nanorod scaffold grown directly on Ni foam. The metallic nature of the Ni3S2 nanorods provides a 1D conductive pathway to the active sites, and their overall nanostructure increases the specific surface area of the electrode and maintains the structural integrity. Furthermore, synergistic interactions between the molybdenum-based nanosheets and NiO nanoparticles can improve the overall activity of the catalyst towards the hydrogen evolution reaction (HER) via playing specific roles in the water dissociation and hydrogen adsorption steps. Consequently, the design of the multi-compositional hierarchical nanostructure led to a remarkable enhancement in electrocatalytic hydrogen evolution performance, and this material also exhibited excellent supercapacitive energy storage properties. This work illustrates a straightforward approach to the design and tailoring of hierarchical nanostructured materials with promising application in the field of energy conversion and storage.