Photothermal properties of aluminum oxide/Ag nanoparticles cermet-based coating synthesized by reactive magnetron co-sputtering

Cermet based-coatings, made of a ceramic matrix and metallic nanoparticles, have attracted a lot of attention in applications such as solar absorbers in a solar concentrating system since they allow a strong solar absorptance, a low IR emittance, and present good thermal stability. It has been shown that many parameters impact the performances of the cermet-based solar absorber such as the thickness, composition, and features of the metallic nanoparticles. In this study, we report on the synthesis of a Al2O3-Ag cermet by reactive co-sputtering of Ag and aluminum in Ar/O2 gas mixtures. The influence of important experimental parameters (i.e. sputtering power on the Ag target, deposition time, and O2 content) on the chemistry, morphology, and optical properties of the cermet coating is studied while the photothermal property of the cermet has been evaluated by measuring the surface elevation temperature of the coating under 1 sun irradiation. Our data reveal that by optimizing the features of the cermet, an absorbance of 0.92 and a surface temperature elevation up to 9.1 K can be reached after 30 min of illumination.