Progress and Perspectives on NiFe Layered Double Hydroxide Catalysts for the Alkaline Oxygen Evolution Reaction

Anion exchange membrane water electrolysis (AEMWE) holds promise for low-cost hydrogen production, thereby addressing the energy crisis humanity faces. Of the two half-reactions, the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), the latter, with sluggish dynamics, is the crucial one toward electrocatalytic water splitting, which requires a non-noble metal catalyst possessing high performance to make the reaction process efficient and economical. Such a condition requires a proper understanding of the reaction mechanism, careful design and optimization of catalyst materials, and maintenance of catalyst durability under AEMWE conditions during long-term operation. NiFe layered double hydroxide (NiFe-LDH), with its unique chemistry and electronic structure that facilitates moderate intermediate adsorption energies and offers tolerance to site deactivation, is of considerable interest as an electrocatalyst. In this review, we systematically discuss the OER catalytic mechanism in alkaline water electrolysis and provide evaluative criteria of the catalytic performance. Also, we summarize the corresponding synthesis strategies and characterization methods for NiFe-LDH catalysts, including morphology control, elemental doping, interfacial engineering, and defect construction. Furthermore, we address the recent bottleneck in developing NiFe-LDH catalysts for the OER under alkaline conditions and their application in AEMWE. Unlike previous reviews that separately discussed OER electrocatalysts or AEMWE operation, this work uniquely bridges the fundamental design of NiFe-LDH catalysts with their integration and performance in practical anion exchange membrane water electrolyzer systems. Finally, we share our thoughts regarding future development directions of NiFe-LDH catalysts toward alkaline OER, a critical step towards the commercialization of water electrolysis technology for green hydrogen production.