In Situ Coupling of Multidimensional MOFs for Heterogeneous Metal-Oxide Architectures: Toward Sensitive Chemiresistors.

ABSTRACT

Metal-organic frameworks (MOFs) are used as a new intriguing class of templates, which enable the creation of porous inorganic nanostructures via calcination. In this work, we first introduce in situ coupling of multidimensional MOFs for producing heterogeneous metal-oxide composite with multiple p-n junctions. Controlling relative ratios of two mixed solvents (water and ethanol), in zeolitic imidazolate framework (ZIF) growth, leads to the distinctive morphological evolution such as rod, sheet, and polyhedron particles. One-pot hybridization of ZIF-8 (sheet) with ZIF-67 (rods) results in the generation of hierarchically assembled 1D ZIF-67 rods anchored on a 2D ZIF-8 sheet. Through the calcination of such hybridized ZIFs, we successfully prepared hierarchically assembled 1D Co3O4 rods immobilized in a 2D ZnO sheet, possessing numerous n-type ZnO/p-type Co3O4 heterogeneous interfaces. This unique structure offers a remarkably enhanced chemiresistive sensing performance (Ra/Rg = 29 at 5 ppm acetone).