Ti₃C₂T_x MXene/delignified wood supported flame-retardant phase-change composites with superior solar-thermal conversion efficiency and highly electromagnetic interference shielding for efficient thermal management

The development of form-stable phase-change material (PCM) with solar-thermal harvest, electromagnetic interference (EMI) shielding, and flame-retardancy is crucial for efficient building energy management and conservation. Herein, novel Ti3C2Tx MXene/delignified wood supported form-stable phase-change composites (PMPCMs) with superior solar-thermal conversion efficiency, highly EMI shielding effects, and excellent flameretardancy were fabricated by alkaline boiling delignification, ammonium dihydrogen phosphate (ADP) and MXene deposition, and melted n-octadecane impregnation. Benefiting from the powerful surface tension and capillary force of the wood-based support materials, PMPCMs can effectively encapsulate the melted n-alkane molecules and inhibit their leakage. The differential scanning calorimetry results showed that PMPCMs possessed superior n-octadecane encapsulation yield and high thermal energy storage density (166.9-191.6 J/g). Decorating delignified wood by MXene significantly improved the solar-thermal storage efficiency (up to 88.4 %) and EMI shielding performance of PMPCMs. The average EMI shielding effectiveness of PMPCM-10 was enhanced to 34.12 dB in X-band frequency range of 8.2-12.4 GHz. Moreover, with the introduction of the flame-retardant ADP, the peak heat release rate (pHRR) and total heat release (THR) of PMPCMs decreased noticeably, demonstrating the enhanced flame retardancy of delignified wood supported phase-change composites. In summary, PMPCMs exhibited superior application prospects in building energy management and electromagnetic shielding fields.