Morphology-engineered ZIF-8-derived porous carbon for high-performance solar thermochemical energy storage

Porous carbon derived from metal-organic frameworks holds immense potential for solar thermochemical energy storage (STES) owing to its high surface area and tunable pore structure. Nevertheless, the lack of elucidation regarding the mechanism by which nano-carrier morphology regulates the STES performance of hydrated salt composites contradicts its versatile applications. Herein, a morphological engineering strategy was employed to synthesize zeolite imidazolate framework (ZIF-8)-derived porous carbon with five different morphologies (rhombic dodecahedron, cube, plate, interpenetrating 36-faced twin, and rod) as adsorption carriers. Furthermore, a systematic investigation was conducted into the structure-property relationship among the carrier morphology, pore structure, and STES performance. Thanks to the loose packing and anti-agglomeration achieved through its locally concave geometric features and hierarchical microporous/mesoporous structure of ITZAC2, the LM2/ITZAC2-60 composite exhibits high moisture absorption capacity, storage density (1407.5 kJ·kg − 1 ), and good operational reliability (95.2% capacity retention after 20-cycle testing), while also demonstrating favorable solar-to-thermal conversion characteristics and heat transfer capability. This work not only reveals the critical mechanisms governing the role of carrier morphology in STES performance, offering a novel strategy for morphological engineering in the rational design of high-performance heat storage materials, but also provides a future-oriented proposition for the implementation of STES materials in buildings.