Dopamine-Decorated Ti₃C₂T_x MXene/Cellulose Nanofiber Aerogels Supported Form-Stable Phase Change Composites with Superior Solar–Thermal Conversion Efficiency and Extremely High Thermal Storage Density

The exploitation of from-stable phase change materials (PCMs) with superior energy storage capacity and excellent solar–thermal conversion performance is crucial for the efficient exploitation of solar energy. Herein, 2D-layered polymerized dopamine-decorated Ti3C2Tx MXene nanosheets (P-MXene) with superior photothermal effects and excellent oxidation stability were synthesized from Ti3AlC2 particles by the selective etching and self-polymerization of dopamine. Then, novel biomass-derived PCM composites, eMPCMs, were fabricated by impregnating erythritol into P-MXene/cellulose nanofiber (CNF) hybrid aerogels. The porous and interconnected 3D aerogels adequately support erythritol and resist liquid leakage during thermal storage. Differential scanning calorimetry (DSC) results showed that the eMPCMs based on P-MXene/CNF aerogels exhibited an extremely high thermal storage density (325.4–330.6 J/g) and excellent PCM loading capacity (up to 1929%). The introduction of P-MXene nanosheets into eMPCMs significantly increased the solar–thermal conversion and storage efficiency, solar–thermal–electricity conversion capacity, and thermal conductivity of the synthesized PCM composites. Moreover, the P-MXene/CNF hybrid aerogel-based PCM composites possessed excellent long-term thermal reliability and thermostability. Hence, the synthesized eMPCMs reveal tremendous potential for efficient solar–thermal storage fields.