Mesoporous Ni–Fe oxide multi-composite hollow nanocages for efficient electrocatalytic water oxidation reactions

Mesoporous NiO/NiFe2O4 multi-composite hollow nanocages via monodisperse Ni3[Fe(CN)6]2 prussian blue analogue nanocube precursors were successfully synthesized. The three-dimensional (3D) mesoporous and hollow structures provided an efficient electrolyte diffusion path and a high surface area, resulting in the enhancement of electrocatalytic activities for the oxygen evolution reaction. The overpotential and Tafel slope of mesoporous NiO/NiFe2O4 multi-composite hollow nanocages were as low as 303 mV at a current density of 10 mA cm-2 and 58.5 mV dec-1, respectively. In addition, the composite showed excellent durability at approximately 60 mA cm-2 for 12 h.