Engineering Gold Nanorod–Copper Sulfide Heterostructures with Enhanced Photothermal Conversion Efficiency and Photostability

Plasmonic gold nanorods (Au NRs)–copper sulfide heterostructures have recently attracted much attention owing to the synergistically enhanced photothermal properties. However, the facile synthesis and interface tailoring of Au NRs–copper sulfide heterostructures remain a formidable challenge. In this study, the rational design and synthesis of Au NRs–Cu₇S₄ heterostructures via a one-pot hydrothermal process is reported. Specifically, core–shell and dumbbell-like Au NRs–Cu₇S₄ heterostructures are obtained with well-controlled interfaces by employing the Au NRs with different aspect ratios. Both core–shell and dumbbell-like Au NRs–Cu₇S₄ have proven effective as photothermal therapy agents, which offer both high photothermal stability and significant photothermal conversion efficiency up to 62%. The finite-difference time domain simulation results confirm the coupling effect that leads to the enhanced local field as well as the optical absorption at the heterostructure interface. Importantly, these Au NRs–Cu₇S₄ heterostructures can be compatibly used as an 808 nm laser-driven photothermal therapy agents for the efficient photothermal therapy of cancer cells in vitro. This study will provide new insight into the design of other noble metal–semiconductor heterostructures for a broad range of applications utilizing surface plasmon resonance enhancement phenomena.