Eutectic phase change composites with MXene nanoparticles for enhanced photothermal absorption and conversion capacity

Abstract

Phase change composite materials with uniform nanomaterial dispersion are potential solutions for improving thermophysical properties and enhancing latent heat capacity applicable in thermal management. In this study, various transitional carbide-based MXene samples were synthesised via acid etching to augment the heat transfer capacity and efficiency of the solar thermal energy storage (TES). These samples were then uniformly dispersed in a eutectic mixture (1:1) of paraffin wax (PW) and polyethylene glycol (PEG-6000), resulting in the formation of a MePCM composite. The controllable porous structure and hydrogen interactions with the external layer of MXene and long-chain PCM benefitted in the well impregnation of PCM and compatibility impregnated into the composite. An exceptionally higher mass fraction of 1 wt % Ti3C2Tx MXene-based phase change composite unveiled a higher phase change enthalpy of 138.66 J/g in the melting phase and 139.54 J/g in the solidification phase with 89.82 % energy storage efficiency. In contrast to pure eutectic PCM (0.2593 W/mK), the thermal conductivity of MePCM composite is relatively higher and provides a thermal conductivity of 0.9209 W/mK for Ti3C2Tx MXene-based composite. The enhancement of thermal conductivity is ascribed to the increased heat conduction pathway facilitated by the MXene arrangement. The utilisation of spatially constrained eutectic phase change material (PCM) assembly resulted in the development of MePCM, which exhibited enhanced thermal conductivity, chemical and physical stability, and thermal consistency across 500 melting-solidification cycles. Benefitting from the thermal conduction path, the MePCM exhibits an excellent photothermal conversion efficiency of 98.53 %. The thermal responsive tests of Ti3C2Tx and V2CTx MXene composite samples provide better thermal response than eutectic PCM without thermal reduction. With a higher thermal storage capacity and higher heat transfer property, thermally reliable MePCM composites exhibited tremendous potential for photothermal applications.