Hierarchical Active Site Engineering in Multicore-Shell nTiO₂@SiO₂ Nanoreactors with PtSA-PtAC Synergy for Enhanced...

To address the persistent challenge of low solar-to-hydrogen (STH) conversion efficiency, it is presented a hierarchical active site engineering strategy via multiscale spatial confinement, implemented in multicore-shell nTiO₂@SiO₂ nanoreactors. This architecture integrates structural confinement and atomic-level Pt speciation to form a unified, multiscale catalytic system. Unlike conventional single-core yolk-shell architectures, the interconnected multicore framework enhances light harvesting through internal multiple light-scattering and effectively suppresses nanocore aggregation. Simultaneously, Pt single atoms and atomic clusters (Pt_SA+C) are confined within the nanoreactors, forming atomically defined heterointerfaces with the TiO₂ nanocores. This dual-scale confinement significantly promotes charge separation and accelerates the hydrogen evolution reaction. As a result, the optimized 0.25 wt.%Pt_SA+C/nT@S catalyst achieves a hydrogen evolution rate of 73.8 mmol g^-1 h^-1 under simulated sunlight-a tenfold increase over Pt_NP/TiO₂-and delivers an apparent quantum efficiency (AQE) of 21.1% at 380 nm. This work establishes a generalizable cross-scale confinement strategy that bridges nanostructure engineering with single-atom catalysis, offering a robust platform for efficient solar hydrogen production and plastic photoreforming.