Recent Progress in NiFe-LDH Electrocatalysts: Synthesis, Mechanisms, and Performance in the Oxygen Evolution Reaction

Nickel–iron layered double hydroxides (NiFe-LDHs) are among the most active earth-abundant electrocatalysts for the oxygen evolution reaction (OER) in alkaline media, yet their performance remains sensitive to structure, electrolyte history, and testing practice. Unlike general summaries of NiFe-LDH synthesis and activity, this review emphasizes the dynamic nature of NiFe-LDHs as precatalysts, focusing on interlayer chemistry, electrolyte history, anodic reconstruction, mechanistic interpretation, and benchmarking reliability. It highlights the activation of NiFe-LDHs under anodic conditions into γ-NiFeOOH-like Ni–Fe oxyhydroxides, where Fe sites embedded in the NiOOH matrix and coupled Ni–Fe motifs jointly govern the catalytic activity. The discussion focuses on the role of layer charge, interlayer anions, layer spacing, and ion/water transport in reconstruction and catalytic activity. Catalyst crystallinity, orientation and loading are also related to common synthesis methods such as coprecipitation, hydrothermal growth and electrodeposition. Moreover, the main performance improvement strategies including defect engineering, heteroatom doping, conductive supports, and interlayer modification are discussed in relation to the adsorption of key OER intermediates. Finally, practical guidelines for reliable benchmarking are discussed, as well as the remaining challenges for the development of stable and efficient NiFe-LDH catalysts for alkaline electrolyzers.