Free-Standing NiO@C Nanobelt as an Efficient Catalyst for Water Splitting

Cost-effective and high-efficiency electrocatalysts for water splitting are important for the production of renewable energy conversion and storage systems. Herein, a 3 D NiO nanobelt electrode was synthesized by direct oxidation of nickel foam using the hydrothermal method. Electrochemical studies reveal that the 3 D NiO nanobelt electrode exhibits excellent electrocatalytic activities for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with low onset overpotential, small Tafel slope, and very eminent electrochemical stability in the standard aqueous solution of 1.0 m KOH. More importantly, the OER activity of 3 D NiO nanobelt can be enhanced by the wrapping of N-doped carbon (NiO@C), which can achieve an overpotential of 500 mV at 100 mA cm⁻², a low Tafel slope of 92 mV dec⁻¹, and distinguished electrochemical stability. This strategy provides a general route to prepare 3 D nanostructured catalyst for water splitting by directly using transition-metal foam as metal source and substrate.