Improving the optical properties of CuCoMnOx spinel absorber using ZnO nanorod arrays for thermal collector and photocatalytic applications

Abstract

Solar-selective and high entropy materials are one of the key factors for thermal applications. CuCoMnOx (CCMO) spinel compound is also a suitable material for this purpose due to its spin-allowed transitions in partially filled d orbitals. In this study, the CCMO absorber compound was coated on ZnO nanorod-coated aluminum (Al) substrates for the first time by the sol-gel dip-coating method, and its optical, structural, and morphological properties were examined. According to the results obtained, ZnO nanorods increased the active surface area of the Al substrate and accordingly increased the absorptance value of the CCMO material from 87 % to 94 %. Analyzes performed with FT-IR spectrometry showed that the thermal emittance values were 90 % and 67 % for Al/CCMO and Al/ZnO/CCMO samples, respectively. The thermal emittance reduced by around 25 % with the use of ZnO nanorods on the Al substrates in the wavelength range of 2.5 μm–25 μm. The photocatalytic effect of this spinel compound was also investigated. The degradation spectra of organic methylene blue (MB) solution within 120 min were examined with UV–Vis spectroscopy, and the degradation efficiency increased by 23 % in the presence of ZnO nanorods. The obtained results showed that ZnO nanorod structures significantly changed both the solar and photocatalytic properties of the CCMO compound.