Comparative study of thermoplasmonic properties in core-shell nanoparticles for heat generation applications

All thermoplasmonic applications have an objective of significantly improving the photothermal conversion of spherical plasmonic nanoparticles, but different core sizes and shell thicknesses provide challenges. In order to examine novel and potential applications, a range of photothermal nanomaterials have been improved with superior light harvesting and photothermal conversion abilities. Here present work described the optical and thermoplasmonic properties of Fe and its oxide and Al and its oxide in spherical core-shell combination with core sizes varying between 20 and 50 nm, and two different shell thicknesses of 5 and 20 nm are investigated by the Mie theory in the water surrounding medium. It is revealed that the LSPR of distinct core-shell nanoparticles could be easily improved by changing the materials and also varying the core sizes as well as the shell thickness. The optical spectra are observed in the range of 230–637 nm wavelengths and merged in the UV-visible-near-infrared region on the electromagnetic (EM) spectrum. Maximum absorption and scattering cross-section are revealed at resonance wavelengths of 442 nm (C_abs≈2.75 × 10^− 14 m²), and 337 nm (C_sca≈4.95 × 10^− 14 m²) for 20 nm shell thickness of Al@ Fe₂O₃. Further, the maximum temperature at the surface of the nanoparticle is observed at 4.13 ⁰ C of Fe@Fe₂O₃, and 6.50 ⁰ C of Al@ Fe₂O₃ with 5 and 20 nm shell thicknesses respectively. The maximum temperature rise and absorption power or heat generation is obtained for iron and its oxide in core-shell i.e. Fe@Fe₂O₃ NPs in the water environment. Moreover, the order of rising maximum temperature of considered NPs in distinct core-shell is as Fe@Fe₂O₃ > Al@Fe₂O₃ > Fe@Al₂O₃ > Al@Al₂O₃. Our findings provide a way to analyze the core-shell nanoparticle’s potential in optical imaging, the biomedical field, therapeutics, and thermal nano-heaters under its LSPR characteristics.