Multi-structured and Ligand Modified NiFe LDH with Self-Optimization for Efficient Oxygen Evolution Reaction.

Nickel foam (NF) self-supported NiFe LDH electrodes have been widely studied for their excellent oxygen evolution reaction (OER) performance. However, these electrodes synthesized via conventional electrodeposition or hydrothermal methods are still unsatisfactory because they have insufficient specific surface area and suboptimal activity. In this study, we report on NF-supported NiFe LDH electrodes directly derived from NF-supported-bimetallic MOF-74(NiFe). The as-prepared NiFe LDH shows a hierarchical structure and inherit the molecule-level porosity of MOF-74 precursor. The as-prepared electrode undergoes self-optimization during the OER process, significantly increasing the electrochemical active surface area and providing numerous catalytic sites. In addition, the 2, 5-dihydroxyterephthalate (DHTP) ligand, released from MOF-74 during its dissociation, enables to chemically modify NiFe LDH. The ligand well promotes the formation of Ni(III) and resists Cl⁻ corrosion. For these reasons, LDH-MOF74@NF superiors to almost all other NiFe LDH@NF electrodes as previously reported in literature, exhibiting excellent OER performance and high durability in both KOH and KOH/NaCl solutions with overpotentials of 244 mV and 254 mV at 100 mA cm-2, respectively.