MOF-on-MOF heterostructures with core–shell and core–satellite structures via controllable nucleation of guest MOFs

The integration of two or more different types of metal–organic frameworks (MOFs) into hybrid MOF-on-MOF heterostructures has been widely studied, and the diversity of MOF-on-MOF heterostructures can be effectively increased by exploring the integration strategy of different MOF building blocks. Here, we report the structure regulation of MOF-on-MOF hybrids via controlling the heterogeneous nucleation and homogeneous nucleation growth of guest MOFs. By using ZIF-90 as the host and ZIF-8 as the guest, binary ZIF-90@ZIF-8 complexes can be synthesized. Moreover, the nucleation mode of ZIF-8 depends on the addition sequence of metal ions and ligands of the guest MOF, including heterogeneous nucleation and homogeneous nucleation. Therefore, ZIF-90@ZIF-8 hybrids with a core–shell structure and smooth surface or a core–satellite structure and rough surface are successfully prepared, increasing the structural diversity of MOF-on-MOF materials.