Photothermal storage and controllable release of a phase-change azobenzene/aluminum nitride aerogel composite

Photochemical phase transition is an effective strategy to realize photothermal conversion and multi-source energy storage. Azobenzene molecule with photo-induced reverse solid-liquid transitions was synthesized through molecular design, achieving multi-source storage for both solar and environmental thermal energy. The energy was stored in the molecular conformation, and could be rapidly released in the form of heat under external stimulation. The molecule exhibited a low crystallization point (cis<0 °C), high isomerization degree (81%), and energy storage capacity (181 J/g). Further, azobenzene was compounded with aluminum nitride aerogel to prepare a solid photothermal composite. The aerogel template was beneficial in increasing the reversion rate of azobenzene in the metastable state. Under blue light irradiation, the charged composites could produce a temperature difference of 1.5 °C, providing a new strategy for exploring self-heating equipment with photothermal storage.