Hollow metal–organic framework polyhedra synthesized by a CO2–ionic liquid interfacial templating route

•The hollow MOF polyhedra were prepared by a CO2–ionic liquid (IL) interface route.•The hollow MOF polyhedra showed applications in gas separation and catalysis.•The CO2–IL interface templating route can be applied to synthesize other MOFs. We proposed for the first time a CO2–ionic liquid (IL) interfacial templating route for the production of hollow MOF microparticles. By adding the gaseous CO2 into IL phase under stirring, a large number of CO2 bubbles are generated, which provide numerous CO2–IL interfaces, serving as the nucleation or agglomeration centers for the MOF nanocrystals. By this strategy, the hollow and mesoporous Zn–BTC (BTC: 1,3,5-benzenetricarboxylic) tetrahedroids were fabricated. The morphologies of the Zn–BTC polyhedra can be easily controlled by CO2 pressure. The as-synthesized Zn–BTC hollow microparticles have shown potential applications in gas separation and catalysis. Furthermore, the CO2–IL interface templating approach has been successfully applied to the fabrication of microsized Zn–BDC (BDC: 1,4-benzenedicarboxylic) hollow prisms.