Mesoporous NiFe2O4 with Tunable Pore Morphology for Electrocatalytic Water Oxidation

Abstract Mesoporous NiFe 2 O 4 for electrocatalytic water splitting was prepared via soft‐templating using citric‐acid‐complexed metal nitrates as precursors. The mesopore evolution during thermal treatment was examined systematically giving insights into the formation process of mesoporous NiFe 2 O 4 . Detailed nitrogen physisorption analysis including desorption scanning experiments reveal the presence of highly accessible mesopores generating surface areas of up to 200 m 2 /g. The ability of the NiFe 2 O 4 powders to perform electrocatalytic oxygen evolution reaction under alkaline conditions was investigated, highlighting the advantages of mesopore insertion. The most active samples reach a current density of 10 mA cm −2 at an overpotential of 410 mV with a small Tafel slope of 50 mV dec −1 , indicating an enhanced activity that originated from the increased catalyst surface.