Preparation and characterization of metal oxide nanofluids for solar thermal application

Abstract

Metal oxide nanofluids are suspensions of metal oxide nanoparticles in a base fluid like water, ethylene glycol, or oil, designed to enhance thermal properties for applications such as solar energy storage. This study focuses on the preparation of metal oxide nanofluids Aluminium oxide (Al₂O₃), Nickel oxide (NiO), and Antimony oxide (Sb₂O₃) using a two-step synthesis method. Nanofluids were formulated by dispersing synthesized nanoparticles of each metal oxide into 20 mL of deionized water, with varying concentrations ranging from 20 mg to 100 mg in 20 mg increments. The optical transmittance of the resulting nanofluids was analyzed using a UV-Vis spectrophotometer, from which absorbance and energy band gaps were determined. The results revealed that as the mass fraction increased, transmittance decreased and absorbance increased, accompanied by a reduction in band gap values
(from 5.5 eV to 1.5 eV). These trends suggest enhanced light absorption and improved electrical conductivity. The findings highlight the potential of metal oxide nanofluids to improve heat transfer performance and support the development of more efficient solar energy systems.