Amorphous/Crystalline Interface of LDH-MOF Heterostructure Enables Efficient Oxygen Evolution Reaction

The pursuit of efficient and durable oxygen evolution reaction (OER) electrocatalysts beyond noble metals is paramount for sustainable hydrogen production. While layered double hydroxides (LDHs) and metal-organic frameworks (MOFs) are promising, they often suffer from poor conductivity, active site aggregation, and unstable reaction pathways. Herein, we develop a hierarchical amorphous/crystalline heterostructure by strategically electrodepositing amorphous NiFe-LDH onto crystalline NiFe-MOF. This unique LDH-on-MOF configuration creates an intimate heterointerface that not only prevents nanosheet stacking but also induces a directional, element-specific charge transfer. Differential electrochemical mass spectrometry (DEMS) measurements reveal lattice oxygen participation in OER, confirming electronic redistribution optimizes metal coordination, thereby activating lattice oxygen and shifting mechanism from conventional adsorbate evolution mechanism (AEM) to more efficient lattice oxygen oxidation mechanism (LOM). The resulting NiFe-LDH@NiFe-MOF/NF exhibits exceptional performance, requiring a low overpotential of 257 mV at 10 mA cm^{- 2} and a small Tafel slope of 56 mV dec^{- 1} in alkaline media, significantly outperforming its individual components and benchmark IrO₂. Furthermore, the catalyst demonstrates remarkable durability for over 100 h and maintains high OER selectivity in simulated alkaline seawater, suppressing the competing chlorine evolution reaction. This work provides a profound insight into steering OER pathways through interfacial electronic engineering for high-performance water splitting.