The Self-Supporting NiMn-LDHs/rGO/NF Composite Electrode Showing Much Enhanced Electrocatalytic Performance for Oxygen Evolution Reaction

The poor conductivity and instability of layered dihydroxides (LDHs) limit their widespread application in oxygen evolution reaction (OER). In this study, the composite electrode of NiMn-LDHs, reduced graphene oxide (rGO) and nickel foam (NF), i.e., NiMn-LDHs/rGO/NF, was prepared by a hydrothermal method. When subjected to oxygen evolution reaction (OER) catalytic performance in a solution of 1 M KOH, the NiMn-LDHs/rGO/NF composite catalyst exhibited an overpotential of only 140 mV at a current density of 10 mA cm(-2) and a Tafel slope of 49 mV dec(-1), which is not only better than the comparing RuO2/NF catalyst, but also better than most of the Mn-based and the Ni-Fe-containing bimetallic OER catalysts reported in the literature. The excellent electrocatalytic performance is ascribed to the efficient integration of ultrathin NiMn-LDH sheets, thin-layered rGO and NF, contributing significantly to the decrease in charge transfer resistance and the increase in electrochemically active surface area. Moreover, NF plays a role of current collector and a role of rigid support for the NiMn-LDHs/rGO composite, contributing extra conductivity and stability to the NiMn-LDHs/rGO/NF composite electrode.