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In situ exsolution for nanoscale electrode design has attracted considerable attention because of its promising activity and high stability. However, fundamental research on the mechanisms underlying particle growth remains insufficient. Herein, cation‐diffusion‐determined exsolution is presented using an analytical model based on classical nucleation and diffusion. In the designed perovskite system, the exsolution trend for particle growth is consistent with this diffusion model, which strongly depends on the initial cation concentration and reduction conditions. Based on the experimental and theoretical results, a highly Ni‐doped anode and an electrochemical switching technique are employed to promote exsolution and overcome growth limitations. The optimal cell exhibits an outstanding maximum power density of 1.7 W cm−2 at 900 °C and shows no evident degradation when operating at 800 °C for 240 h under wet H2. This study provides crucial insights into the developing and tuning of heterogeneous catalysts for energy‐conversion applications.

Nanostructured catalytic materials are considered to be a favorable design concept for various energy conversion and storage systems. Nanosized metal catalysts supported on oxide scaffolds have been adopted in numerous fields, including fuel cells, gas sensors, and chemical reforming devices. Nevertheless, nanometal catalysts often suffer from durability issues. Although surface-decorated nanometal catalysts can deliver sufficient catalytic activity, some of them still exhibit durability issues in severe operating environments. Recently, nanocatalysts produced by in situ exsolution have been demonstrated to overcome the practical limitations of conventional nanometal catalysts. The exsolution is defined as a process in which a catalytically active dopant in perovskite oxide is exsolved on its surface as highly dispersed nanometal catalysts. In particular, exsolution nanocatalysts embedded on perovskite oxides exhibit higher nanoparticle densities and greater resistance to particle agglomeration than conventional nanometal catalysts. This Perspective presents an overview of recent advances in exsolution materials for energy applications including fundamental mechanisms, design strategies for host oxides, and practical applications. The future prospects of these materials and the scope for further optimization are also discussed.

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