A wet impregnation approach to synthesize MIL-101(Cr) with open metal sites and their application in the adsorption of volatile organic compounds

Abstract

The simple wet impregnation method reported a series of MIL-101(Cr) materials doped with copper acetate paddle wheel species. Powder X-ray diffraction and SEM studies showed the MOF frameworks remained intact during wet impregnation, and SEM- EDX, XPS, and N2 adsorption analyses confirmed the successful copper acetate loading. Volatile organic compounds adsorption capabilities of these materials were further examined, and it found that copper acetate doped MIL-101 (Cr) possesses up to 61% improvement in toluene uptake as compared to pristine MIL-101 (Cr) at a low partial pressure of P/P0 = 0.10 under 298.1 K. This performance improvement is attributed to the unsaturated open metal sites introduced by molecular copper acetate with a paddle wheel structure. This study provides not only a new series of promising VOC removal MOFs with unsaturated Cu(II) open metal sites but also a simple, widely applicable method for introducing Cu(II) open metal sites into MOFs by using molecular copper species with predefined paddle wheel structure.