Photothermal halloysite aerogel encapsulating phase change materials for solar-driven seawater desalination

Abstract

The inherent limitations of phase change materials (PCMs), namely liquid-phase leakage and insufficient intrinsic light absorption, pose significant challenges to their scalable application in photothermal conversion and storage systems. This study employs polydopamine (PDA) pre-coated halloysite nanotubes (HNTs) as fundamental building blocks to construct a three-dimensional porous aerogel (PHG), which is subsequently utilized to encapsulate polyethylene glycol (PEG). A synergistic effect between the HNTs aerogel and the PDA coating leads to a collaborative enhancement of the composite PCMs (PEG/PHG). The porous structure of PHG guarantees a high encapsulation efficiency of 93.1% and a latent heat of 166.7 J g⁻¹, whereas the PDA coating boosts the photothermal conversion efficiency to 92.88%. The exceptional thermal management and highly efficient photothermal conversion capabilities of PEG/PHG are key enablers for its deployment in solar-driven seawater desalination. The PEG/PHG-integrated evaporator combines the dual advantages of high-efficiency solar-driven operation and sustained performance during intermittent periods. It achieves a high evaporation rate of 3.03 kg m⁻² h⁻¹ under one sun irradiation, while also maintaining a continuous evaporation performance of 1.47 kg m⁻² h⁻¹ even in the absence of light. Therefore, this research successfully integrates photothermal composite PCMs with solar-driven seawater desalination, paving the way for their application and offering new avenues for future development.