Solvent induced phase transformations of ZIF-L to ZIF-8 and their derivatives’ gas sensing properties

Abstract

Detailed study of topological phase transition is essential in guiding the controlled synthesis of materials. Herein, a series of zeolitic-imidazolate frameworks (ZIFs) and derived metal oxide with tailored morphologies and adjustable phases from ZIF-L to ZIF-8 to ZnO were reported. More significantly, the phase transformation and morphology control of the product can be achieved by simply changing the molar/volume ratio of reagents without adding any surfactant, and the growth mechanism was systemically investigated. Benefiting from their unique structural advantage, when fabricated gas sensors, all of the product and their derivatives exhibited excellent gas-sensing selectivity and rapid response/recovery time toward acetone vapor. In addition, the gas sensing mechanism and the causes for gas sensing performance discrepancy in different sensors were also studied, and the results show that the oxygen vacancies content (OV), structures and morphologies of the product are closely related to their comparable sensitivities. The phase transition and morphology evolution of ZIFs and ZnO in this work might bring a deep understanding of the metal-organic framework crystallization process, which is expected to develop more precise control strategies of MOF-based materials with customized function properties.