A bottom-up sonication-assisted synthesis of Zn-BTC MOF nanosheets and the ppb-level acetone detection of their derived ZnO nanosheets

Two-dimensional metal-organic framework nanosheets, as a new member of the two-dimensional family, are attracting increasing research interest in various fields. Herein, a uniform two-dimensional Zn-BTC MOF nanosheet with a thickness of 14 ± 2 nm was synthesized through a simple, efficient, and scalable sonication-assisted bottom-up strategy. The ZnO nanoparticles were used as the Zn source, which can be corroded by H3BTC to form Zn-BTC MOFs under sonication conditions. The morphologies of Zn-BTC MOFs can be modulated from nanosheets to nanorods by changing the content of H3BTC. The crystal growth process is dominated by the thermodynamics of sonication and the stoichiometric ratio of the generated Zn2+ and H3BTC, and the crystal growth mechanism was elaborated by the oriented attachment. Consequently, a chemiresistive gas sensor based on Zn-BTC nanosheet derivatives was fabricated to detect ppb-level acetone. Notably, the experimental detection limit of concentration could reach as low as 100 ppb of acetone due to the functional surface, and the dynamic response linearity reached 99 %. Our work explored a new method of synthesizing two-dimensional Zn-BTC MOF, and the fabricated gas sensing device demonstrated promising potential in gas sensing fields.