MXene-modified bio-based pitaya peel foam/polyethylene glycol composite phase change material with excellent photo-thermal conversion efficiency, thermal energy storage capacity and thermal conductivity

Abstract

The preparation of multifunctional composite phase change materials (CPCM) for efficient conversion and storage of solar energy using green technology remains a big issue. Herein, in this research, a novel CPCM was prepared for the first time by encapsulating polyethylene glycol (PEG) into MXene-modified pitaya peel-based porous carbon using a simple vacuum impregnation method. Pitaya peel-based porous carbon was selected as the carrier to coat with MXene nanosheets to construct a continuous three-dimensional thermal conductivity network. The MXene-modified bio-based pitaya peel foam/polyethylene glycol composite phase-change material (PEG/BPC@M) exhibited high loading ratio (95.4 %) and enthalpy (154.9 J/g). Interestingly, due to the introduction of MXene nanosheets, both the photothermal conversion (θ = 92.9 %) and thermal conductivity (2.34 times that of PEG) of PEG/BPC@M were substantially increased. Significantly, PEG/BPC@M with outstanding thermal stability, wherein the PEG/BPC@M still maintained enthalpy values similar to those in non-thermal cycles after 100 cycles, further proving that PEG/BPC@M has outstanding reusability. This study provided a simple and green novel process for the preparation of multifunctional CPCM, similarly, it provided a feasible scheme for waste reuse, which has huge potentials for the field of solar energy conversion and storage.