Electrooxidation-enabled electroactive high-valence ferritic species in NiFe layered double hydroxide arrays as...

Currently, engineering non-precious NiFe layered double hydroxide (NiFe-LDH) electrocatalysts with excellent oxygen evolution performances at high current densities is highly critical to promoting electrolytic water splitting producing hydrogen for large-scale commercial applications. Herein, an intrigued oxygen vacancy-rich Fe(Ⅱ)-incorporated NiFe-LDH containing electroactive high-valence ferritic species is successfully grown on Ni foam (Fe²⁺-NiFe-LDH-EO6 h@NF) through an elaborate two-step route including hydrothermal and electrooxidation, and utilized as a high-efficiency elctrocayalyst of alkaline water oxidation possessing abundant exposed active sites, excellent intrinsic catalytic activity and superior durability. Therefore, the Fe²⁺-NiFe-LDH-EO6 h@NF electrocatalyst towards oxygen evolution reaction (OER) enables the low overpotentials of 239, 285 and 350 mV for the current densities of 10, 100 and 500 mA cm^-2, respectively, a small Tafel slope of 48.3 mV dec^-1, the low onset potential of 1.451 V, and retains the catalytic activity for 40 h at the large current density of 500 mA cm^-2 as well as owns the high turnover frequency (TOF) value of 0.93 s^-1 at the overpotential of 300 mV. This work provides a promising avenue to improve the OER performances of NiFe-LDH electrocatalyst for practical applications.