Construction of Hierarchical Porous Architecture on Ni Foam for Efficient Oxygen Evolution Reaction Electrode

Nickel foam (NF) with a three-dimensional porous structure plays an important role in a wide variety of applications such as energy storage and conversion, catalysis, and sensor due to its high porosity, low density, and excellent conductivity. However, the main drawback of NF is that its ligaments are very smooth, and thus the surface area is relatively low. In this work, we propose a novel strategy, oxidization and reduction process, in situ to construct micron/nano pores on the ligaments of commercial NF to fabricate a typical hierarchical porous architecture. This process is simple and green, avoiding the use of sacrificial materials. Furthermore, MnO₂ is coated on the micron/nano-porous Ni foam (MPNF) to construct an oxygen evolution reaction (OER) electrode through pulse electrodeposition. The designed MPNF-MnO₂ electrode presents enhanced OER electrocatalysis activity with a low overpotential of 363.5 mV at the current density of 10 mA cm⁻² in an alkaline solution, which is 66.4 mV lower than that of the NF-MnO₂ electrode in the same operating conditions. Furthermore, the porous and wrinkled structures of the MPNF also improve the mechanical integrity of the electrode, resulting in super-long stability.