Hollow mesoporous NiCo2O4 nanocages as efficient electrocatalysts for oxygen evolution reaction

Abstract

The design and fabrication of efficient and inexpensive electrodes for oxygen evolution reaction (OER) is essential for energy-conversion technologies. Herein, high OER activity is achieved using hollow mesoporous NiCo₂O₄ nanocages synthesized via a Cu₂O-templated strategy combined with coordination reaction. The NiCo₂O₄ nanostructures with a hollow cavity, large roughness and high porosity show only a small overpotential of ∼0.34 V at the current density of 10 mA cm⁻² and a Tafel slope of 75 mV per decade, which is comparable with the performance of the best reported transition metal oxide based OER catalysts in the literature. Meanwhile, the positive impacts of the nanocage structure and the Ni incorporation on the electrocatalytic performance are also demonstrated by comparing the OER activities of NiCo₂O₄ nanocages with Co₃O₄ nanocages, NiCo₂O₄ nanoparticles and 20 wt% Pt/C. Moreover, the NiCo₂O₄ nanocages also manifest superior stability to other materials. All these merits indicate that the hollow mesoporous NiCo₂O₄ nanocages are promising electrocatalysts for water oxidation.