Abstract
Photocatalysis is increasingly becoming a center of interest due to its wide use in environmental remediation. Hematite (α-Fe2O3) is one promising candidate for photocatalytic applications. Clay materials as vermiculite (Ver) can be used as a carrier to accommodate and stabilize photocatalysts. Two different temperatures (500 °C and 700 °C) were used for preparation of α-Fe2O3 nanoparticles/vermiculite clay materials. The experimental methods used for determination of structural, optical and photocatalytic properties were X-ray fluorescence (ED-XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDS), N2 adsorption method (BET), diffuse reflectance UV-Vis spectroscopy (DRS), photoluminescence spectroscopy (PL) and photocatalytic reduction of CO2, respectively. The data from XRD were confronted with molecular modeling of the material arrangement in the interlayer space of vermiculite structure and the possibility of anchoring the α-Fe2O3 nanoparticles to the surface and edge of vermiculite. Correlations between structural, textural, optical and electrical properties and photocatalytic activity have been studied in detail. The α-Fe2O3 and α-Fe2O3/Ver materials with higher specific surface areas, a smaller crystallite size and structural defects (oxygen vacancies) that a play crucial role in photocatalytic activity, were prepared at a lower calcination temperature of 500 °C.
Highlights
In recent years, many researchers have focused on catalysts employing supports composed of natural clay minerals, which are abundant, obtainable and inexpensive materials
Pure α-Fe2 O3 nanoparticles were synthesized with the chemical precipitation method from the FeCl3 ·6H2 O precursor
Chemical elemental analysis was performed using the energy dispersive X-ray fluorescence (ED-XRF) spectrometer SPECTRO XEPOS (Spectro Analytical Instruments GmbH, Kleve, Germany) to determine amount of α-Fe2 O3 anchored on vermiculite substrate
Summary
Many researchers have focused on catalysts employing supports composed of natural clay minerals, which are abundant, obtainable and inexpensive materials. Each 2:1 layer of such clay mineral is of the (TOT) type consisting of two tetrahedral (T) Si-O sheets and an octahedral (O) Al-O/Al-OH sheet between them. Experimental studies have indicated that electron transfer to/from clay mineral structure takes place through either edge sites, or through the basal surface [5]. The structural iron content can be used to examine the extent of reduction and oxidation of Fe-bearing mineral clay [7]). The structural, optical and photocatalytic properties of α-Fe2 O3 nanoparticles/vermiculite clay materials, synthesized by the precipitation procedure from the FeCl3 ·6H2 O and NaOH precursors were studied after annealing samples at 500 ◦ C and 700 ◦ C for 4 h
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