Nickel nanoparticle anchored 3D carbon nanotube sponge: a free-standing catalyst electrode for efficient water...

Non-precious nickel (Ni)-based catalysts suffer from surface corrosion-induced active site degradation, high oxygen evolution reaction (OER) overpotential at low current density, insufficient conductivity and poor dispersion of active components during catalytic processes. In this study, we prepared an efficient and stable composite electrode (Ni/CNT) consisting of loaded Ni nanoparticles with uniform distribution and consistent size on three-dimensional porous carbon nanotube (CNT) sponge. The Ni/CNT electrode fabricated under optimal conditions demonstrated overpotentials of 180 mV for OER and 79 mV for the hydrogen evolution reaction (HER) at a current density of 10 mA cm^-2 in 1 M KOH solution. In addition, the Ni/CNT electrode has a potential of 1.55 V at a current density of 10 mA cm^-2 when used as both anodic and cathodic catalysts in the overall water splitting system. Meanwhile, it maintained remarkable durability after 40 hours of continuous operation under constant voltage. This study provides a feasible approach for the performance improvement of non-precious metal catalysts, contributing to the development of high-performance Ni-based electrochemical catalysts.