Experimental Study on a Superstable Nano-TiO2 Deep Eutectic Solvent Nanofluid for Solar Energy Harvesting

Abstract

Nanofluids have emerged as an important working fluid for various heat transfer and thermal energy transportation demands thanks to its promising thermal conductivity. While, poor static stability brought by segregation of nanoparticle heavily hinders its wide practical utilization. In this work, a novel “one-pot one-step” strategy was realized to generate a superior stable nanofluid which can stand uneventfully for at least 2 months without observation of any sedimentation with tetrabutyl titanate as a TiO2 precursor in glycerol/chlorine chloride deep eutectic solvents. Mechanism study reveals that the good stability of this nanofluid is mainly attributed to in situ formation protocol for which the inherent aggregation of TiO2 can be theoretically avoided. Meanwhile, thermophysical properties, such as viscosity, thermal conductivity, and rheological behavior, were comprehensively studied, which indicates that the obtained nanofluids exhibit a non-Newtonian shear thinning fluid behavior with a thermal conductivity enhancement ratio up to 9.0%. More importantly, photothermal conversion efficiency of the nanofluid could reach 51.2%, and the efficiency enhancement is 181.9% over the pristine deep eutectic solvents. This work paves a novel avenue for fabricating nanofluids with super static stability and gives a supplementary idea for “one-step” nanofluids preparation process.