Rare Earth‐Modified Electrocatalysts for Water Splitting: Material Design, Synthetic Strategies and Mechanistic Insight

) is a promising clean energy carrier due to its high gravimetric energy density and zero carbon emissions. Electrocatalytic water splitting provides an efficient route to produce high-purity hydrogen using renewable power. Rare-earth (RE) elements exhibit unique 4f electronic configurations that effectively regulate the electronic structures, active sites, and reaction paths of electrocatalysts. Despite significant progress, a comprehensive review of RE-doped electrocatalysts for water splitting remains lacking. This Review Systematically Summarizes Recent Progress in RE-doped Electrocatalysts For the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). It elaborates Core Design Principles and Structure-Activity Relationships, including (i) 4f-d electronic synergies that optimize charge distribution and intermediate adsorption, (ii) RE-induced Defect Engineering and Lattice Modulation That Increase Active-Site Density and Structural Stability, and (iii) the doping strategies across metal oxides, layered double hydroxides, metal-organic frameworks, phosphides, sulfides, and heterostructures. The review also analyzes the electronic regulation mechanisms in typical catalyst platforms and clarifies corresponding doping strategies and electrochemical applications. Finally, key challenges and future perspectives are outlined to guide the design of high-efficiency, durable, and scalable RE-doped electrocatalysts for water splitting.