Metal@Semiconductor Core@Shell and Yolk@Shell Nanostructures for Photocatalytic Hydrogen Production

Photocatalytic hydrogen production is a promising pathway to sustainable hydrogen, yet practical deployment requires simultaneous advances in light harvesting, interfacial charge separation, and durability for photocatalyst designs. This review examines metal@semiconductor core@shell and yolk@shell nanostructures, where targeted modulation of core composition, shell thickness, void size, and yolk morphology governs charge dynamics and surface reaction kinetics, the primary determinants of photocatalytic performance. We catalog a synthesis toolbox spanning one‐step and two‐step routes, galvanic replacement, Kirkendall conversion, and ion exchange, and map each method to the resulting architectures to guide selection of chemistries aligned with specific material sets and performance goals. Representative case studies show how core/yolk/shell engineering and support immobilization strengthen interfacial charge transfer and enhance operational stability. Furthermore, we distill practical design rules and present a standardized performance summary that benchmarks best‐in‐class systems. Finally, we identify remaining challenges and outline actionable solutions, thereby guiding the rational development of next‐generation core@shell and yolk@shell photocatalysts.