Spectral properties of nanofluids with homogeneous and bilayer nanoparticles for efficient absorption of solar radiation

Abstract

The optical properties of metal monodisperse nanoparticles (nickel (Ni) and titanium (Ti)) with radii of 50–100 nm and of bilayer nanoparticles that consist of a metal core and a spherical shell made of oxide of the same metal have been studied theoretically in the spectral interval 250–2500 nm, and the results of the study have been analyzed. The influence of the parameters of nanoparticles (radius, nanoparticle shell thickness, etc.) and of the surrounding liquid (water) on the optical-absorption, scattering, and radiation-extinction cross sections of nanoparticles has been investigated. It has been found that, for certain values of the particle radius, Ti + TiO₂ and Ni + NiO nanoparticles are good radiation absorbers, especially in the ultraviolet, visible, and near infrared spectral ranges, and they can be used for purposes of solar-thermal energetics.