Thermally Triggered In Situ Template-Escape Strategy for Controlled Construction of Hollow MOFs

Abstract

Hollow spherical structures can endow metal–organic framework (MOF) materials with new capabilities. However, devising an uncomplicated synthesis method for hollow MOF spheres remains a formidable challenge. Here, the green hydrothermal method is employed to drive the polymer template, inducing a thermal transition (viscous flow state) that facilitates escape and enables the construction of a series of hollow MOF spheres. The hollow MIL-101(Cr) spherical capsules (Void@MIL-101) with high stability and well-defined morphology are synthesized as the first example. After encapsulating Pd nanoparticles, it exhibits an accelerated mass transfer effect and superior catalytic selectivity in synthesizing secondary aromatic amines. Furthermore, the versatility of this in situ template-escape strategy is demonstrated through the successful construction of hollow CPM-243(Cr) and SiO₂ spheres. This innovative approach opens new avenues for the development of various hollow materials with enhanced properties.