ZnAl-LDH/MOF-5 heterostructure nanocomposite for photocatalytic degradation of organic dyes under sunlight irradiation

Abstract

Layered double hydroxide based metal organic framework-5 (LDH/MOF-5) nanocomposite is synthesized by in situ nucleation and directed growth of MOF-5 crystals on LDH layers. The intercalated benzene dicarboxylate (BDC) ions of the LDH structures coordinate to the Zn2+ ions to form MOF-5 crystals, which are deposited on the surface of the LDH. The structural and morphological analyses of the LDH/MOF-5 nanocomposite are carried out by powder X-ray diffraction (PXRD) analysis, field emission scanning electron microscopy (FESEM), Fourier transform-infrared spectroscopy (FTIR), optical spectroscopy and thermo gravimetric analysis (TGA). Thus, the synthesized ZnAl-LDH/MOF-5 nanocomposite exhibits enhanced dye removal efficiency, compared to pure LDH and MOF-5. The nanocomposite is very selective towards the removal of anionic dyes. The methyl orange (MO) dye adsorption efficiency of ZnAl-LDH/MOF-5 is 51.41% and shows a plateau after 60 min of contact time. The ZnAl-LDH/MOF-5 nanocomposite exhibits an excellent dye removal efficiency of 99.98% after 40 min by a natural sunlight mediated photodegradation process. Such an efficient photocatalytic removal of toxic anionic dyes indicates the potential applications of the ZnAl-LDH/MOF-5 nanocomposite in industrial waste-water treatment.