Synthesis of hierarchically porous Cu-BTC through phase-controlled etching

Abstract

To enhance diffusion channels and boost active sites within microporous metal–organic frameworks, hierarchically porous structures are indispensable. This study pioneered phase-controlled acetic acid etching techniques, encompassing solution etching and steam etching resulting in the successful synthesis of a series of hierarchically porous Cu-BTC (HP-Cu-BTC). In contrast to etching with an acetic acid solution, acetic acid steam etching offers advantages in terms of reduced etchant usage and minimized damage to the original microporous structure. Noteworthy, by employing steam-controlled recovery etching technology, it is possible to regulate both the steam concentration and the etching degree, while also facilitating the recovery of etchant. The prepared HP-Cu-BTC exhibits adjustable pore sizes (15–45 nm), and mesopore volume (0.14–0.23 cm3/g). Compared to the original Cu-BTC, the well-engineered HP-Cu-BTC demonstrates an 81 % increase in ethylene diffusion rates. The phase-controlled synthesis of HP-MOFs serves as a valuable source of inspiration for the future preparation of hierarchical porous structures.