Abstract

Commercial solar selective absorbers prepared through several techniques have encountered drawbacks of necessitating complicated and expensive equipment, substantial materials requirement, and polluting environ-ment. In this context, carbon incorporated metal oxide thin films have shown promise of low-cost, non-toxic, and efficient solar selective absorbers. In particular, association of reduced graphene oxide (rGO) and nickel oxide (NiO) could facilitate highly ascertained optical properties, environment friendliness, and low-cost. Present study focuses on preparing a novel, high performance, and low-cost rGO-NiO solar selective absorber thin films. Thin films comprised of reduced graphene oxide modified nickel oxide nanocomposites (rGO-NiO NCs) were prepared through solvothermal route and coated on aluminum (Al) substrates by dip-coating technique. The rGO-NiO NCs examined using X-ray diffractometer revealed formation of face centered cubic crystallite structure. The scanning electron microscope images disclosed spherical morphology of NiO decorated on the rGO sheets. The spectra derived from energy-dispersive X-ray spectroscopy ascertained absence of peaks corresponding to impurities. The Raman investigation exhibited high intensity ratio (0.97) of the rGO-NiO NCs that described higher disorder and binding sites. The optical property analysis of the rGO-NiO NC (0.2 wt% rGO) thin film performed in UV-vis-NIR reflectance spectroscopy showed high absorptance (alpha = 88.03 %) and low thermal emittance (e = 4.5 %), which eventually delivered high solar selectivity (xi) of 19.56. These findings suggest that the prepared 0.2 % rGO-NiO NC thin film can be utilized as an appropriate selective absorber for solar to thermal energy conversion.