Tuning the modal coupling in three-dimensional Au@Cu₂O@Au core–shell–satellite nanostructures for enhanced plasmonic photocatalysis

The fascinating optical properties of coupled plasmonic nanostructures have attracted great attention and emerged as a promising platform for applications in catalysis, sensing, and photonics. When two resonant modes interact strongly, the coupled modes are formed with mixed properties inherited from the basic modes. However, limitations still exist in the understanding of the coupling between optical modes in individual structures. In addition, how the coupling in hybrid plasmonic structures correlated with their efficiencies in promoting photocatalysis remains an important and challenging question. Here we demonstrate that coupling in individual Au@Cu₂O@Au core-shell-satellite hybrid structures can be tuned through rationally designing the structural features for enhancing plasmonic photocatalysis. To further comprehend the optical phenomena of different coupled nanostructures, a model was developed based on the Mie theory, which provided a different perspective to analyze coupling qualitatively in individual nanoparticles. The insights gained from this work not only shed light on the underlying mechanisms of modal coupling in individual structures but also provide an important knowledge framework that guides the rational design of coupled plasmonic nanostructures for plasmonic photochemistry and photocatalysis.