Porous and electrically conductive materials having extended surface area are attractive for wide range of applications, such as catalysis, sensing or energy storage. High surface area of the material provides higher reaction rates and lower electrode resistance. For instance, metallic sponges such as Raney nickel, having surface areas up to 100 m²/g show high catalytic activity during water electrolysis or heterogenous organic synthesis. However, low porosity and small average pore diameter limit their application for devices utilizing additional functional layers (e.g. active electrode materials in batteries). On the other hand, highly porous nickel foams are commonly used as current collectors for Ni- and Zn-based batteries, where sufficient loading of active material can be realized inside of the porous network. However, the surface area of such foams is more than three orders of magnitude smaller than that of the metallic sponges, lowering the potential for e.g. high rate operations of their parent devices.

In this talk we will present a recently developed material composed of interconnected nickel nanowires of controllable diameter and distance. The nanowires assembly offers a unique combination of high surface area of metallic sponges and high porosity of metallic foams. The material is conveniently obtained by cheap and up-scalable electrochemical techniques. The unique nanostructural properties of the interconnected nanowires allow for high flexibility of the material and applications in e.g. flexible electronics or wearable sensors. As a proof-of-concept, we will present the performance of our structure for hydrogen generation during water electrolysis. Compared to nickel foams, the high surface area interconnected nanowires offers significantly higher hydrogen evolution currents, showing their potential for next generation electrolyzers and energy devices.