Structural Characterization and Photoluminescent Behavior of CO3Intercalated Zn-Fe Layered Double Hydroxide (LDH) and its Colloids

Carbonate intercalated Zn-Fe layered double hydroxide (LDH) with Zn2+/Fe(3+)molar ratios 2, 3 and 4 were synthesized by coprecipitation in order to study the photoluminescent (PL) properties of their colloids with various wt.% of LDH in formamide. These synthesized LDHs were characterized by various techniques including x-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron mMicroscopy (FE-SEM), energy-dispersive x-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HR-TEM), and photoluminescence spectroscopy (PL). The rhombohedral phase and crystallite size of Zn-Fe LDH were confirmed by XRD. Crystallite size plays an important role in the PL mechanism. HR-TEM showed hexagonal nanosheets with 5-6 nm average particle size. To investigate the PL mechanism of pristine LDH and their colloids, these prepared Zn-Fe LDHs were exfoliated in formamide by varying their Zn2+/Fe(3+)molar ratios (2,3, 4) and LDH concentration (0.2 wt.%, 0.4 wt.%, 0.6 wt.%, 0.8 wt.% of LDH). Results revealed that surface charge density and surface defects are the main reasons for PL generation in LDH colloids.