“…For example, ultrasmall noble-metal NCs embedded within a microporous inorganic matrix can serve as thermally stable supported catalysts during gas-phase reactions , and demonstrate superior stability as compared with NCs modified inside mesopores, tubes, or layers, where free-to-move NCs can lose their reactivity upon sintering. ,, In recent years, the encapsulation of noble-metal NCs within inorganic oxides with a core–shell configuration has been extensively investigated. − The main function of the encapsulating shell material is to act as a physical shield that prevents the coalescence of metal NCs, suppressing their further growth and inducing interfacial metal–support interactions, which alter the catalytic activity. ,− To implement NSC-SSRs, the outside barrier (shell) must be sufficiently thermally, chemically, and mechanically strong to sustain the harsh thermal reaction conditions while being sufficiently porous to allow gaseous transport. In this regard, silica is a suitable nanosized material for use as an embedding medium owing to its good thermal stability, chemical inertness, tunable porosity, facile synthesis, and ability to form a tight conformal shell around a wide range of NCs. ,,− After the reaction, silica can be easily removed by hydrolytic etching, leading to surfactant-free NCs for further applications. Within the scope of NSC-SSR research to date, the major focus has been on SiO 2 nanospheres embedded with different metal ions and/or NCs, which are subjected to high-temperature (>500 °C) redox conditions.…”