Synergistic Effect Induced High Photothermal Performance of Au Nanorod@Cu7S4 Yolk–Shell Nanooctahedron Particles

Au nanorod (NR) which has strong LSPR (longitudinal surface plasmon resonance) effect in near-infrared (NIR) region was introduced into the Cu 7 S 4 hollow NPs to form Au NR@Cu 7 S 4 yolk–shell structured nanoparticles (YSNPs) for improving the photothermal property of NPs. The optimum photothermal conversion efficiency of the as-prepared YSNPs is 68.6%. The hybrid YSNPs had the highest photothermal property compared with the equivalent used Au NR and pure Cu 7 S 4 because of the synergistic effect of metal and semiconductor. In this case, the synergistic effect in YSNPs was discussed by tuning sizes of the YSNPs and the thickness of Cu 7 S 4 shell. The experimental results demonstrated that the NIR photoabsorption and the photothermal conversion performance of Au NR@Cu 7 S 4 YSNPs were much dependent on the geometric change of YSNPs, since the electrical field interaction between inner Au NR core and outer Cu 7 S 4 shell is closely effected by the distance of two materials and thickness of out-shell, as confirmed by the 3D finite-difference time domain simulation (FDTD) theory simulation. Moreover, we proved that the hollow yolk–shell structure of the YSNPs also endowed the NPs with a large potential in drug delivery.