Tunable 3D hierarchical Ni3S2 superstructures as efficient and stable bifunctional electrocatalysts for both H2 and O2 generation

Three-dimensional (3D) nanomaterials have received significant attention for large-scale functional applications due to their large specific surface areas as well as desired electrical, physicochemical, and catalytic properties. Herein, we present a facile and effective synthetic route for in situ grown 3D hierarchical Ni3S2 superstructures (rod-like arrays and nanoforest patterns) on nickel foam. This handy strategy endows the Ni3S2 superstructures with large surface active areas, porosity, and macro-/mesoporous structures. We have shown that these materials can serve as highly active, binder-free, bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Moreover, these materials were found to provide a ∼100% faradaic yield towards both HER and OER and exhibit remarkable catalytic stability (for >50 h).