Engineering Plasmon-Semiconductor Coupling in Spatially Ordered Supraparticles for Boosted Photocatalytic Hydrogen Evolution

Organizing distinct nanocomponents into spatially ordered architectures offers a powerful strategy to regulate light-matter interactions and enhance photocatalytic efficiency, yet remains largely underexplored. Herein, we report the bottom-up construction of colloidal supraparticles (SPs) comprising photocatalytic CdS-based and plasmonic Au nanoparticles (NPs), forming spatially ordered hybrid superstructures with tunable Au NP size and compositional ratios. The optimized CdSe@CdS-Au SPs achieve a hydrogen evolution rate of 160 mmol h⁻¹ g⁻¹ under visible light, representing a significant enhancement over the mixture of the same components and outperforming previously reported similar NP-based systems. Ultrafast spectroscopic analyses combined with finite element simulations reveal that spatial confinement facilitates plasmon-mediated interactions between Au and CdSe@CdS NPs, leading to enhanced plasmonic local electric fields and efficient plasmon-induced resonance energy transfer from Au to the semiconductor domains. These photophysical advantages collectively account for the markedly improved photocatalytic activity. This study demonstrates nanoscale spatial engineering as a versatile strategy for tailoring hybrid architectures toward high-efficiency solar-to-chemical energy conversion.