Engineering Yolk–Shell\nCo-CN@SiO<sub>2</sub> Nanoreactors for Efficient Selective Hydrogenation\nof Aromatic Aldehydes

The\nincreasing demand for sustainable and efficient catalytic processes\nhas driven the development of advanced nanoreactors. In this study,\nwe present a sophisticated Metal–organic framework (MOF)-template-mediated\napproach to synthesize yolk–shell Co-CN@SiO<sub>2</sub> nanoreactors,\nwhere Co nanoparticles were supported on carbon nitride (C–N)\nnanosheets as the core encapsulated within a nanoporous SiO<sub>2</sub> shell. This yolk–shell structure with confined cavities can\nprovide a high surface area and overcome challenges such as Co nanoparticle\nsintering and mass transport limitations, resulting in superior catalytic\nperformance. Remarkably, these nanoreactors achieved a 99% yield of\nbenzyl alcohol from benzaldehyde hydrogenation under base-free conditions.\nMoreover, the influence of calcination temperatures on the structural\nevolution of the Co-based silica nanoreactors was explored, revealing\nthe critical role of synergistic interaction between C–N and\nCo nanoparticles in boosting catalytic activity. Density functional\ntheory calculations were conducted to investigate the adsorption energies\nof reacting species on the catalyst, providing mechanistic insights\ninto the enhanced hydrogenation activity of the Co-CN@SiO<sub>2</sub>. This work offers valuable insights into the rational design of\nadvanced nanoreactors for various catalytic applications, particularly\nin the field of green chemistry and sustainable synthesis.