Yuzhou Wu,Jiawei Wu,Chuang Zhu,Liang Zhang,Jianhua Yan
Continuous TiO 2 nanofibers (NFs) with the merits of high photochemical activity, adjustable active sites, and easy to recycle have triggered a huge interest in the catalysis fields. Nevertheless, they are easy to break due to the intrinsic brittleness of ceramic TiO 2 . Here, we report a Mxene-intercalation toughening strategy to fabricate flexible TiO 2 NF films with a sol–gel electrospinning method followed by a low-temperature calcination. The in-situ doping of MXene (Ti 3 C 2 T x ) nanosheets in TiO 2 NFs reduces the grain sizes and introduces 2D defective MXene-derived TiO 2 planes, the former creates sinuous grain boundaries that can reduce crack propagation, while the latter generates elastic brick–mortar structures of allomorph junctions that can absorb more external work. The dual functions remarkably enhance the breaking strength of TiO 2 NFs from 0.06 to 0.16 MPa. Fascinatingly, this strategy reduces the bandgap of TiO 2 and more efficiently conduct photogenerated carriers. The evolution rate of photocatalytic CO 2 reduction into CH 4 reaches 31.6 μmol/g/h without using sacrificing agents and photosensitizers. The reported facile strategy simultaneously enhances the flexibility of TiO 2 nanofibers and photocatalytic efficiency.
Molten salts are widely used as thermal energy storage materials for solar thermal applications, but they suffer from low photothermal conversion efficiency and potential leakage and corrosion issues. In this paper, MXene doping was proposed to improve the thermal properties and photothermal conversion efficiency of microencapsulated molten salts. MXene nanomaterials, which have excellent thermal conductivity and photothermal conversion efficiency, were used to dope the molten salts. The results tested by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) indicate that MXene was well doped in the molten salt microcapsules. Fourier transformation infrared (FT-IR) spectroscopy was used to confirm that the microencapsulation of the molten salt by silica is a physical action. The results of X-ray diffractometry (XRD) show that the crystal structure of the molten salt maintained stability. The results obtained from the Hot Disk thermal constant analyzer and photothermal conversion experiments showed that thermal conductivity and photothermal conversion efficiency of the MXene-doped microcapsules were increased by 156.2% and 169.4%, respectively. The differential scanning calorimeter (DSC) results indicated that the MXene-doped microcapsules had a reduction of 49.6% in the supercooling degree. The thermal reliability of the MXene-doped microcapsules was 94.0% after 50 thermal cycles. This approach provides a promising solution for improving the thermal properties and photothermal conversion efficiency of microencapsulated molten salts for medium-temperature solar thermal energy storage.
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.
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