Carbon Surfaces Doped with (Co3O4-Cr2O3) Nanocomposite for High-Temperature Photo Thermal Solar Energy Conversion Via Spectrally Selective Surfaces

Invention new thin films nano-coating to obtain high-level performance spectrally selective surfaces to enhance solar energy by spin and casting methods, thin films coating are deposited by these techniques on aluminum and glass substrates that were pre-cleaned. Nanocomposite thin film coating comprising (Co3O4:Cr2O3) and carbon to gain an economical coating. The coating has a high absorptivity of solar energy. Nanomaterials have been used in various concentration ratios to dope carbon, and Energy Dispersive Analysis (EDX) was used to determine carbon ash's chemical composition; SEM measured its practical size. Optical properties have been studied by the UV-Visible Spectra and reflectivity tests in a range from 250-1300 nm at room temperature. Absorbance coefficient, transmittance, reflectance, skin depth, optical density, optical energy gap (Eg), and Urbach energy of nanocomposite thin films have also been specified. The Eg of doped C has been measured with different concentration ratios of (Co3O4:Cr2O3) such as sample F (0.5:2.5/7), sample G (1:2/7), sample H (1.5:1.5/7), the sample I (2:1/7), and sample K (2.5:0.5/7) wt. %, the concentration of C is fixed for all samples (7) wt. %. The results revealed that the Eg is ranged (2.9-3.9 eV) and the absorptivity in the ranged (88-93.2 %) for all doped samples. The absorptivity values of nanocomposites are very close to semiconductor elements, which have high absorptivity to the wavelength intensity. The synthesized coating will be used over a flat plate collector as a trap to absorb solar energy for a highly feasible selective surface.