Synergistic Effect of N-Doped Carbon and Mn in NiFe LDH To Achieve 1 A cm–2 Current Density for the Oxygen Evolution Reaction

The development of highly efficient oxygen evolution reaction (OER) electrocatalysts is pivotal to enhance the performance of alkaline water electrolyzers. Herein, a facile two-step electrodeposition method is developed for the fabrication of nitrogen-doped carbon (NC) and manganese-incorporated NiFe layered double hydroxides (LDHs) supported on Ni foam (NF). When evaluated in 1.0 M KOH solution, the optimized material of NC20-Mn-NiFe LDH showed excellent OER performance requiring low overpotentials of 298 and 331 mV to achieve high current densities of 500 and 1000 mA cm–2, respectively, and no loss in current density was observed at fixed potentials of 1.53 and 1.57 V for 125 h in each case. This performance is not only better than that of the state-of-the-art RuO2/NF but also most of the recently reported LDH-based catalysts. Such a remarkable performance is mainly attributed to the vertical growth of NC20-Mn-NiFe LDH sheets on NF, facilitated electron transfer and charge density modulation on the active metal sites due to the electron-withdrawing and electron-donating effects of NC and Mn, respectively, resulting in the shift of the rate-determining step from OOH* formation to O2 desorption with decreased free energy. This research work provides further insights into modulating the structure of LDH-based materials to achieve a high OER performance delivering industrial-level current densities at low overpotentials.