Hierarchical Active Site Engineering in Multicore-Shell nTiO@SiO Nanoreactors with PtSA-PtAC Synergy for Enhanced Solar Hydrogen Evolution.

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 nTiO@SiO 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) are confined within the nanoreactors, forming atomically defined heterointerfaces with the TiO nanocores. This dual-scale confinement significantly promotes charge separation and accelerates the hydrogen evolution reaction. As a result, the optimized 0.25 wt.%Pt/nT@S catalyst achieves a hydrogen evolution rate of 73.8 mmol g h under simulated sunlight-a tenfold increase over Pt/TiO-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.