Ultrathin Ni–Fe MOF nanosheets: efficient and durable water oxidation at high current densities

Efficient, durable, and economical electrocatalysts are crucial for advancing energy technology by facilitating the oxygen evolution reaction (OER). Here, ultrathin Ni-Fe metal-organic skeleton (MOF) nanosheets were in situ created on nickel foam (NiFe-UMNs/NF).
The catalyst exhibited excellent OER catalytical abilities, with only 269 mV overpotentials at
250 mA cm -2. Besides, when integrated with Pt/C/NF, NiFe-UMNs/NF held the potential for
application in industrial alkaline water electrolysis with initial voltage retention of approximately
86% following a continuous operation of 100 h at a current density of 250 mA cm -2 . The super
performance of the NiFe-UMNs/NF catalyst is attributed to ultra-thin morphology, super
hydrophilicity, and synergistic effects between Ni and Fe within the MOF. In situ Raman showed
that NiFe-UMNs were converted to NiFeOOH as the active species in the OER process. Density
Functional Theory (DFT) revealed that iron doping accelerated the rate-determining step and
reduced the OER reaction energy barrier. This work elucidated a promising electrocatalyst for
OER and enriched the practical implementation of MOF materials.