TiN supported 3D directional tubular skeleton encapsulating phase change materials for efficient solar-thermal energy conversion and storage

Phase change materials (PCMs) have problems of melt leakage, weak sunlight absorption, and low photothermal conversion efficiency, which greatly limit their applications in efficient solar energy utilization and latent heat storage. In this study, a novel TiN-based composite PCMs was prepared by encapsulating polyethylene glycol (PEG) in the photothermal conversion capable CNF/PVA/TiN (C-CPT) carbon aerogel skeleton composed of cellulose nanofibers (CNF)/polyvinyl alcohol (PVA)/titanium nitride (TiN). The unique three-dimensional (3D) directional tubular porous structure of C-CPT aerogel not only effectively inhibited PEG leakage, but also created directional heat transfer pathways to improve the thermal conductivity. Meanwhile, the incorporation of TiN significantly improved broadband light absorption capacity across the UV–vis-NIR spectrum. Leveraging the synergistic effect of TiN and graphitized C-CPT aerogel, the C-CPT/PEG-15 % exhibited high latent heat capacity of 174.1 J/g, excellent energy storage efficiency of 99.87 %, and remarkable photothermal conversion efficiency of 94.2 %. After 100 thermal cycles, the C-CPT/PEG composite PCMs demonstrated excellent thermal cyclic stability and structural stability. The C-CPT/PEG composite PCMs with superior energy storage performance, photothermal conversion efficiency, and shape stability will provide innovative insights for the development of novel plasmonic photothermal PCMs.