Rational design and controlled synthesis of MOF-on-MOF heterostructures: Overcoming lattice mismatch

The construction of well-defined MOF-on-MOF heterostructures is significantly challenged by lattice mismatch between dissimilar frameworks. Here, we report a precisely controlled core–shell MIL-101(Fe)@CoZn-ZIF composite with a uniform “one-to-one” encapsulation structure, overcoming the intrinsic incompatibility between octahedral MIL-101(Fe) cores and tetrahedral Zeolitic Imidazolate Framework (ZIF) shells. This achievement is realized through two synergistic strategies: nucleation kinetics modulation and surfactant-mediated interfacial engineering. Systematic optimization of key parameters, including the Co 2+ Zn 2+ to Fe 3+ molar ratio (120:1), precursor concentration (150 mM), and ligand to metal ratio, enabled dimensional matching and uniform coating. Moreover, surfactants (Cetyltrimethylammonium bromide and Polyvinylpyrrolidone) effectively reduced the heterogeneous nucleation barrier, promoting oriented ZIF deposition onto MIL-101(Fe). Comprehensive characterization (SEM, TEM, XRD, FTIR, TGA, XPS and BET) confirms the well-defined hybrid architecture. When the PVP-mediated composite material was applied in sulfate radical-based advanced oxidation processes for degrading methylene blue and p-nitrophenol, it demonstrated enhanced performance and stability compared to the pristine CoZn-ZIF. This work establishes a generalizable approach for integrating topologically mismatched MOFs, advancing the design of multifunctional materials for catalysis and related fields.