Fabrication of mesoporous NiFe2O4 nanorods as efficient oxygen evolution catalyst for water splitting

Designing and fabricating inexpensive, active oxygen evolving catalysts are significant for promoting the performances of water splitting. Here we report the synthesis of mesoporous, one-dimensional NiFe2O4 spinel by thermal decomposing of NiFe-based coordination polymer precursor. The annealed temperature and structural/compositional of these as-prepared electrocatalysts were found to have a striking correlation with their electrocatalytic water oxidation properties. The NiFe2O4 nanorods with a surface area of 165.9 m2/g obtained at 350 °C was found to be the most active oxygen evolving catalyst in alkaline solution, an overpotential of 342 mV at 10 mA/cm2 with a Tafel slope of 44 mV/dec was detected, comparing with those of electrocatalysts obtained under other decomposed temperature. The OER mechanism in alkaline electrolytes on NiFe2O4 was also proposed. The high oxygen evolving activity can be attributed to the mesoporous one-dimensional nanostructure with abundant surface electrochemically active sites and improved electric conductivity, thus facilitating the charge/electron transfer and further improving the efficiency of water electrolysis. The efficient water oxidation activity and scalable, low-cost synthesis make the NiFe2O4 nanorods a very attractive oxygen evolving catalyst using for water splitting.