Multi-structured and ligand-modified NiFe LDH with self-optimization for efficient oxygen evolution reaction

Abstract

Nickel foam (NF) self-supported NiFe LDH electrodes have been widely studied for their excellent oxygen evolution reaction (OER) performance. However, the performance of electrodes synthesized via conventional electrodeposition or hydrothermal methods are still unsatisfactory owing to their insufficient specific surface area and suboptimal activity. In this study, we report NF-supported NiFe LDH electrodes directly derived from NF-supported-bimetallic MOF-74(NiFe). The as-prepared NiFe LDH exhibited a hierarchical structure and inherited the molecular level porosity of the MOF-74 precursor. The as-prepared electrode underwent 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 chemically modified NiFe LDH. This ligand promoted the formation of Ni(III) and resisted Cl⁻ corrosion. Thus, LDH-MOF74@NF outperformed almost all previously reported NiFe LDH@NF electrodes, exhibiting excellent OER performance and high durability in KOH and KOH/NaCl solutions with overpotentials of 244 mV and 254 mV at 100 mA cm⁻², respectively.