Light-driven phase change microcapsules modified by TiN/CNTs nanocomposites for enhancement of solar energy storage and solar photocatalytic efficiency

The development of microencapsulated phase change materials (PCMs) integrating solar photothermal conversion and storage holds significant for solar energy utilization. Herein, this study developed an efficient light-driven phase change microcapsule system by encapsulating paraffin within a brookite TiO2 shell through sol-gel interfacial polymerization, followed by wrapping titanium nitride (TiN)/carbon nanotubes (CNTs) nanocomposites on the shell surface. The microcapsule system exhibited a regular spherical core-shell structural morphology. The encapsulation of TiO2 and the introduction of the highly thermal conductivity enhancement phase increased the thermal conductivity of the microcapsule system by approximately 151.5 % compared to pure paraffin while maintaining latent heat of over 135 J·g−1. Furthermore, TiN/CNTs were combined with the microcapsule shell through hydrogen bonds and shared electron pairs, constructing localized surface plasmon resonance (LSPR)-enhanced heterojunction. The microcapsule system demonstrated excellent broad-spectrum light absorption capacity, resulting in a remarkable 112.01 % enhancement in the optimum photothermal conversion efficiency. Concurrently, the degradation rate of MB was increased by 59.52 % due to the synergistic catalytic action of photothermal, semiconductor, and LSPR effects. The microcapsule system also exhibited excellent thermal and cycling stability, with only 1.6 % latent heat loss after 500 thermal cycles. This study provides a promising strategy for developing energy storage microcapsule composite PCMs for the efficient collection and utilization of solar energy.