N-eicosane@TiO2/TiN composite phase change microcapsules: Efficient visible light-driven reversible solid-liquid phase transition

Organic phase change materials (PCMs) promise remarkable latent heat storage capacity but suffer from weak visible-light absorption capability and ultralow thermal conductivity for harvesting and conversion of clean solar energy. Herein, we design and synthesize a new core@shell structured n-eicosane@TiO 2 /TiN composite microcapsules which can realize 98.08 % of thermal energy storage capacity. By making use of the localized surface plasmon resonance of high-thermal-conductivity TiN, the prepared composite microcapsules possess a remarkable photo-thermal conversion efficiency up to 78.4 %. Plasmonics TiN can not only efficiently adsorb visible light and convert the optical energy into heat but also enhance thermal conductivity of the composite microcapsules, resulting in ultra-low supercooling degree of 1.02 o C. In addition, the composite microcapsules exhibit excellent phase change reversibility and thermal durability during the 100-cyclic scans. Our work offers new insights into designing high-performance microcapsuled PCMs in solar thermal applications, bringing great potential for renewable energy utilization beyond traditional fossil energy sources. • A facile one-pot approach for microcapsules with n-eicosane core and TiO 2 shell embedded by TiN particles was reported. • The microcapsules exhibited visible light-driven phase change and remarkable photo-thermal storage efficiency of 78.4 %. • Ultra-low supercooling degree of 1.02 ℃ was achieved by addition of the thermoplasmonic TiN particles.