Formation of a Single-Crystal Aluminum-Based MOF Nanowire with Graphene Oxide Nanoscrolls as Structure-Directing Agents

An innovative strategy is proposed to synthesize single-crystal nanowires (NWs) of the Al3+ dicarboxylate MIL-69(Al) MOF by using graphene oxide nanoscrolls as structure-directing agents. MIL-69(Al) NWs with an average diameter of 70 +/- 20 nm and lengths up to 2 mu m were found to preferentially grow along the [001] crystallographic direction. Advanced characterization methods (electron diffraction, TEM, STEM-HAADF, SEM, XPS) and molecular modeling revealed the mechanism of formation of MIL-69(Al) NWs involving size-confinement and templating effects. The formation of MIL-69(Al) seeds and the self-scroll of GO sheets followed by the anisotropic growth of MIL-69(Al) crystals are mediated by specific GO sheets/MOF interactions. This study delivers an unprecedented approach to control the design of 1D MOF nanostructures and superstructures.