Enhanced thermal conductivity and photothermal conversion efficiency of MXene-doped sugar alcohol nanocapsules for medium-temperature solar utilization

The utilization of sugar alcohols as phase change materials (PCMs) in medium-temperature solar thermal applications has significant potential, yet their utilization is limited by their low thermal conductivity and potential leakage during the phase change process. In order to achieve greater thermal conductivity and higher photothermal conversion efficiencies, this study proposes the incorporation of MXenes within inositol nanocapsules. The structures and thermal properties of the resulting nanocapsules were methodically examined through Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) and the Brunauer–Emmett–Teller (BET) method. The thermal conductivity of the nanocapsule suspension was measured using a hot disk thermal constant analyzer. Furthermore, the temperature variations of the nanocapsule suspension, subjected to simulated solar irradiation, were measured and the photothermal conversion efficiencies were calculated. The findings of the study reveal that MXene doping had negligible impact on the latent heat of the nanocapsules. However, it was found that the thermal conductivity of the nanocapsule suspension was enhanced by 76.0% in comparison to that of the inositol suspension that contained an equivalent mass fraction of 2.0%. Moreover, the photothermal conversion efficiency of the nanocapsule suspension exhibited a 67.3% increase relative to that of the inositol suspension. These results indicate that the MXene-doped sugar alcohol nanocapsules demonstrate promising potential for enhancing the efficacy of solar thermal utilization.