High thermal storage ability and photothermal conversion capacity phase change capsule with graphene oxide covalently grafted silica shell

Preparation of phase change materials with energy collection, conversion and storage functions is considered to be an important way to solve the energy shortage problem. Hence, a novel phase change capsule ([email protected]) with photothermal conversion function was innovatively designed. In the process of preparing [email protected], the modified graphene oxide (MGO) layer was covalently anchored on the surface of the phase change capsule encapsulated by silica shell (EP) through Si-O-Si bonds, in which MGO was obtained by modifying GO nanosheets with isocyanate propyl triethoxysilane. The as-prepared [email protected] microcapsule presents favorable latent heat storage capacity, with enthalpy of 139.8 J/g and high encapsulation efficiency of 83.6%. Besides, the thermal stability, leakage-proof property, durability, and thermal reliability of [email protected] were enhanced significantly due to the physical protection effect provided by the SiO2-MGO double-layer shell. Moreover, the covalently MGO-grafted silica shell endows [email protected] with high thermal conductivity (1.603 W/m·K), which improves its thermal management efficiency. More importantly, [email protected] exhibits the potential ability to effectively utilize ultraviolet and visible light. In detail, the absorbance of [email protected] increased by ∼192% in the ultraviolet and visible light region (200–800 nm), and the photothermal conversion efficiency under near infrared (NIR) region as high as 64.4%, which has negligible change (64.2%) even after 50 times heating-cooling cycle. Therefore, the phase change capsule [email protected] provides a new idea for realizing efficient utilization of solar energy, and exhibits the application potential in biomedical treatment, smart textiles, and solar thermal collector.