Multiple-Interfacial Plasmon Coupling and Carrier Dynamics in Au@Cu 2– x S@Au Hybrids for Photothermal-Assisted Photocatalysis

Rationally engineering plasmon coupling and interfacial carrier dynamics in plasmonic nanostructures represents a pivotal challenge in plasmon-driven energy conversion. Herein, we investigate the strong multiple plasmon coupling and carrier dynamics in a core–shell–satellite nanostructure composed of Au nanoparticles deposited on Au@Cu2–xS core–shell nanorods, and demonstrate its efficient photothermal-assisted photocatalytic performance. The Au@Cu2–xS@Au hybrids exhibit intense light absorption in both the near-infrared and visible regions, arising from strong multiple interfacial plasmon coupling among Au nanorods, Au nanospheres, and Cu2–xS. Numerical simulations reveal that multiple-interfacial coupling among these components significantly enhances the local electric field, light absorption, and photothermal conversion efficiency. Femtosecond transient absorption spectroscopy reveals that hot electrons generated via plasmon excitation and interband transitions from the inner Au nanorods and outer Au nanoparticles can be transferred to Cu2–xS, whereas hot holes from the plasmon band of Cu2–xS migrate to the Au nanoparticles and nanorods within the core–shell–satellite architecture. Under 808 and 980 nm laser irradiation, the Au@Cu2–xS@Au hybrids exhibit substantially enhanced photothermal conversion relative to Au NRs, Cu2–xS, and Au@Cu2–xS. As a result, the Au@Cu2–xS@Au nanostructure achieves efficient photothermal-assisted photocatalytic degradation of organic dyes under 808 nm laser irradiation, driven by the strong plasmon coupling, efficient charge separation, and superior photothermal conversion. This work clarifies the mechanisms underlying plasmon coupling and carrier dynamics in multiplasmonic materials, offering valuable insights for the design of high-performance plasmonic materials for energy conversion.