Defect‐Engineered Hierarchical Pores in Covalent Organic Cages Enable Ultrahighly Active Pt Catalysis for Hydrosilylation

Abstract The hydrosilylation of alkenes is pivotal for organosilicon synthesis in materials and pharmaceuticals, yet traditional Pt catalysts face challenges of low activity toward bulky substrates and poor selectivity. This study introduces Pt@Defect‐Cage, a novel catalyst with hierarchical pores (12.5 Å) engineered via defect engineering in a covalent organic cage (COP1‐T derivative). At an ultra‐low Pt loading of 0.0712 mmol%, it achieves 100% conversion of allylbenzene within 120 min, outperforming the Karstedt catalyst (12% conversion) and defect‐free COP1‐T‐Pt (60% conversion). Molecular dynamics (MD) simulations reveal that enlarged pores reduce steric hindrance, facilitating substrate diffusion to active sites. Density functional theory (DFT) calculations show defect‐modulated Pt sites lower the activation energy of the oxidative addition step (22.24 versus 26.83 kcal/mol for COP1‐T‐Pt). The catalyst retains 85% of its initial turnover frequency (TOF = 680 h −1 ) after five cycles, attributed to the cage framework suppressing Pt aggregation. This work provides a synergistic platform to overcome traditional catalysts’ bottlenecks, offering a rational design strategy for porous metal catalysts in hydrosilylation and advancing sustainable organosilicon synthesis.