Selective Solar Absorbers’ Properties of Laser Treated Electrodeposited Tubular Co-Al2O3 Nanocomposites

This contribution reports on the morphological and optical properties of laser surface structured tubular Co-Al2O3 nanocomposites consisting of oriented Co nanocylinders embedded in porous Al2O3 host matrix. The electrodeposition of the Co nanocylinders onto the porous alumina arrays is a suitable technique to produce nanomaterials, since highly ordered uniform nanomaterials can be obtained simply and in a cost effective way. A femtosecond fiber laser pulsing at the fundamental wavelength of 1064 nm was used to surface structure the thin film Co-Al2O3 composites. The structural characteristic of the samples was examined using XRD, SEM, EDS and AFM; which confirm the cobalt nanocylinders formation. Their optical properties investigated by specular and diffuse reflectance gave an elevated optical absorptance α(λ) above 98% and an emittance ɛ(λ) ∼0.03 in the spectral range of 200-1100 nm. This makes the nanocylinders potential candidates as mid-temperature selective solar absorbers.