Recent advances in Metal@Silica yolk-shell nanoparticles for catalysis, biomedical, and environmental applications

Yolk-shell nanoparticles featuring a metal core (yolk) and a silica (SiO 2 ) shell represent a highly versatile and impactful class of nanostructures. This specific architecture is advantageous because it provides essential protection for the functional metal core, isolating it within a void space to prevent aggregation or deactivation, while simultaneously enabling the integration of diverse functionalities. The silica shell offers crucial properties, including chemical/thermal stability, biocompatibility, tunable mesoporosity, and facile surface functionalization. This review summarizes the principal synthetic strategies used to fabricate metal@silica nanostructures (template-based, ship-in-a-bottle, and post-encapsulation) and discusses the recent progress in this field. We highlight the significant developments across their major application fields in catalysis, biomedical platforms, and environmental remediation. Finally, we conclude by addressing the key challenges and prospects that must be overcome for widespread implementation, including scalability, long-term durability, in vivo targeting, and economic feasibility. • Key properties of silica-shell yolk-shell (stability and biocompatibility) are discussed. • Synthetic strategies (template-based, ship-in-a-bottle, and post-encapsulation) are summarized. • Elaboration of nanoreactor functions of yolk-shell for catalytic applications. • Recent advances in biomedical and environmental applications are presented. • Current challenges and prospects for yolk-shell implementation are analyzed.