Atomic Layer Deposition for Water Electrolysis Electrocatalysts: From Atomic‐Scale Control to Electrode Engineering

Atomic layer deposition (ALD) has emerged as a powerful fabrication strategy for the design of advanced electrocatalysts for water electrolysis. Owing to its sequential self‐limiting surface reactions, ALD enables atomic‐scale control over film thickness, composition, morphology, and interface structure, while simultaneously providing highly conformal coatings on complex and porous substrates. These characteristics make ALD particularly attractive for engineering electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), where catalyst utilization, stability, and interface properties critically influence electrochemical performance. Beyond catalyst synthesis, ALD has also emerged as a powerful platform for disentangling structure‐activity‐stability relationships in electrocatalysis. This review discusses recent advances in ALD‐enabled electrocatalyst fabrication for water electrolysis, with emphasis on noble‐metal and earth‐abundant catalyst systems, including transition‐metal oxides, sulfides, and phosphides. Attention is given to the role of ALD in controlling catalyst dispersion, stabilizing active phases, tuning oxidation states, and engineering catalyst–support interactions. In addition, recent developments in interface engineering, ultrathin overlayers, and phase‐controlled oxide systems are highlighted. Finally, current limitations associated with scalability, throughput, and processing cost are discussed together with future perspectives involving spatial ALD (SALD), plasma‐enhanced ALD (PEALD), and operando characterization approaches for next‐generation water electrolysis technologies.