Core-ring structured NiCo2O4 nanoplatelets:: Synthesis, characterization, and electrocatalytic applications

An innovative nanostructure, namely the core-ring structure, is reported in this paper. It occurs in NiCo2O4 nanoplatelets., synthesized by the coprecipitation decomposition method using sodium hydroxide as the precipitant. The yield of core-ring hexagonal NiCo2O4 nanoplatelets is greater than 80% at 200 degrees C. A high-resolution transmission electron microscopy and energy dispersive spectroscopy investigation reveals the typical core-ring nanostructure, which shows a strong enrichment of Co in the core with a Co content higher than 80%. A mechanism for the core-ring structure formation is proposed. The core-ring NiCo2O4 can be used as an electrocatalyst for an oxygen evolution reaction (OER) in alkaline water electrolysis. Compared with the electrodes of ordinary NiCo2O4 and Co(3)O4, or other NiCo2O4 electrodes prepared by alternate methods, the electrode coated by core-ring NiCo2O4 nanoplatelets exhibits the greatest electrocatalytic properties, with an over-potential of 0.315 V at a current density of 1.00 mA cm(-2).