NiCo‐Layered Double Hydroxides as Tunable Electrocatalysts for Efficient Alkaline Oxygen Evolution Electrocatalysis

The oxygen evolution reaction (OER) is a major kinetic bottleneck in alkaline water electrolysis, motivating the development of efficient, durable, and cost‐effective electrocatalysts. This review critically examines NiCo layered double hydroxides (NiCo‐LDHs) as earth‐abundant OER precatalysts, emphasizing how synthesis, structural modification, and operando reconstruction govern catalytic performance. Reported design strategies are evaluated according to the key limitations they address, including insufficient active‐site accessibility, suboptimal intrinsic activity, poor electrical conductivity, restricted mass transport, uncontrolled reconstruction, and limited scalability. The crystal chemistry, interlayer structure, and anodically induced transformation of NiCo‐LDHs into catalytically active Ni/Co oxyhydroxide‐like phases are discussed as a basis for understanding structure–activity relationships. Major synthesis and modification approaches, including morphology control, heteroatom doping, defect engineering, conductive‐support integration, interface engineering, and heterostructure formation, are critically compared in terms of activity, transport, durability, fabrication complexity, and structural stability. Particular emphasis is placed on post‐OER, in situ, and operando characterization for identifying working‐state structures. Finally, challenges in electrochemical benchmarking, metal dissolution, substrate effects, long‐term stability, and scalable fabrication are assessed, providing design principles for advancing NiCo‐LDH‐based electrodes toward practical alkaline water electrolysis.