Preparation of 3 D oriented porous titanium nitride aerogel-based composite phase change materials for efficient solar energy photothermal conversion and storage

Phase change materials (PCMs) suffer from issues such as leakage in the molten state, weak solar absorption capacity, and low photothermal conversion efficiency, which severely restrict their applications in efficient solar energy utilization and latent heat storage. In this study, a novel TiN aerogel-based composite PCMs was successfully fabricated by encapsulating polyethylene glycol (PEG) within a skeleton of TiN-PVA-CNF (TPC) aerogels, which was constructed via the crosslinking of titanium nitride (TiN), polyvinyl alcohol (PVA), and cellulose nanofibers (CNF). The TPC aerogel skeleton possesses a unique three-dimensional oriented tubular porous structure, which not only effectively suppresses PEG leakage but also significantly enhances the capture of incident light through multiple reflections within the channels. Meanwhile, the localized surface plasmon resonance effect of TiN significantly enhances the broadband light absorption capability of PCMs in the solar spectrum. Leveraging the synergistic effect between TiN and the TPC aerogels, the TPC-15%/PEG exhibits a high latent heat capacity of 142.2 J/g, a photothermal conversion efficiency of 87.2%, excellent shape stability. After 100 thermal cycles, the TPC/PEG composite PCMs still maintain good heat storage capacity. This study provides a new strategy for developing novel plasmonic photothermal PCMs with high photothermal conversion efficiency, excellent shape stability, and high energy storage density.