CNT/MXene Aerogel Phase Change Composites for Efficient Solar–Thermoelectric Conversion

Traditional phase change materials (PCMs) have problems such as leakage, low energy storage efficiency, and poor photothermal conversion performance. n-Eicosane (C20) was used as the PCM and poly(vinyl alcohol) (PVA) aerogel used as the support framework. We added carbon nanotubes (CNT) and Ti3C2 MXene into the aerogel to improve the photothermal conversion properties. A composite PCM C20/CNT/MXene/PVA (C20/CMPA) with photothermal storage and efficient photothermal conversion properties was obtained. The prepared C20/CMPA7 has relatively high enthalpy of fusion and enthalpy of solidification, which are 195.2 J g–1 (86.1% of C20) and 192.1 J g–1 (91.5% of C20), respectively. The C20/CMPA7 exhibits excellent light absorption performance and photothermal conversion efficiency. Under the simulated sunlight irradiation of 1.5 kW m–2, the photothermal conversion efficiency of C20/CMPA7 reaches 97.71%. Significantly, the surface temperature of C20/CMPA7 rose to 70.7 °C within 1500 s. We designed a typical solar thermoelectric generator using the prepared composite material, which successfully achieved the conversion of solar thermal energy. The output voltage and current were 343.36 mV and 31.31 mA, respectively, at 2000 s, which could maintain additional working time even in dark conditions. This work provides insights into the design of solar-driven thermal interface materials and the clean production of electricity.