Surface segregation and reconstruction of core–shell electrocatalysts for water splitting

Electrochemical water splitting to produce large-scale hydrogen is a leading sustainable energy development technique to mitigate carbon emissions. Among the most promising electrocatalysts, core–shell nanoarchitectures have garnered significant attention due to their exceptional turnover frequencies. While substantial progress has been made in the synthesis and design of these structures, critical insights into their dynamic behavior—especially, their chemical stability and structural evolution under operating conditions (applied bias and electrolytic environment)—remain underexplored. This review addresses this gap by first examining the contemporary challenges in the design and synthesis of core–shell catalysts. It then delves into the fundamental phenomena of surface segregation and reconstruction, analyzing the kinetic and thermodynamic factors that drive these morphological changes. By correlating these dynamic processes with catalytic activity through advanced characterization techniques, we provide a framework for understanding structure–performance relationships. This review aims to provide rigorous insights into reported core–shell materials and literature inferred suggestions for designing efficient and stable catalysts for overall water-splitting.