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.