Photothermal Conversion Property of (Au Nanocup)-(Cu₂O Nanocube) Hybrids Supported by MXene Nanosheets

Integrating multiple mechanisms to optimize electromagnetic field enhancement and charge transfer is vital for maximizing the photothermal conversion efficiency. In this study, a structurally tunable ternary plasmonic hybrid, with (Au nanocup)-(Cu₂O nanocube) hybrids dispersed upon two-dimensional Ti₃C₂T_X MXene ultrathin nanosheets, is prepared and employed for photothermal conversion application. The Au–Cu₂O nanostructures are synthesized through a process involving the overgrowth of Cu₂O nanocubes, with controlled size and quantity, onto the surface of the Au nanocups. Furthermore, transferring the Au–Cu₂O nanostructures onto plasmonic Ti₃C₂T_X nanosheets generates further enhanced electromagnetic field intensity around their interface. The photothermal conversion evaluation indicates that the photothermal conversion performance of the MXene/Au–Cu₂O hybrids is significantly improved, achieving a photothermal conversion efficiency of 51.2% under 808 nm laser excitation, which is attributed to the magnetic plasmon resonance of the Au nanocups, the hot hole injection process due to the multisite growth of Cu₂O, and the electric field enhancement at the MXene and Au–Cu₂O interface. This work provides a promising approach to improve photothermal conversion efficiency through the multisite growth of Cu₂O.