Reconstruction mediated lattice oxygen mechanism on hierarchical LDH/MOF nanoarrays for efficient oxygen evolution

Abstract Developing highly active, cost-effective, and durable nonprecious electrocatalysts is critical for advancing alkaline water electrolysis. However, the origin of activity and reaction pathway are significantly influenced by anode reconstruction effects, which remain unclear and expedite the further exploration. Herein, we propose a hierarchical catalyst, composed of bimetallic metal-organic framework (MOF) nanosheets supported on layered double hydroxide (LDH) nanorods. During the oxygen evolution reaction (OER), Co ions diffuse to the surface and accelerates the structural evolution, simultaneously inducing the transformation of NiFeOOH from γ-phase to β-phase and lowering the reconstruction voltage from 1.5 V to 1.3 V. The resultant catalyst Nickel–cobalt layered double hydroxide supported on NiFe–BDC (BDC = 1,4-benzenedicarboxylate) metal–organic framework (NiCo-LDH/NiFe-BDC). achieves ultralow overpotentials of 180 and 255 mV at 10 and 500 mA/cm2, respectively, and maintains stable operation at 500 mA/cm2 over 500 h. The pH-dependent OER performance, molecular probe analysis, online measurement of 18O-labelled catalyst, and theoretical calculations collectively indicate that the generated Co-NiFeOOH serves as the active species and the reduced Ni–O–Fe bonding activates lattice oxygen mechanism (LOM). This work not only offers an insightful view on OER-driven reconstruction process, but also correlates it to the catalyst’s electronic structure and the reaction mechanism, which may inspire innovative design of OER catalysts.