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.

Clay is an abundant raw material which has a variety of uses and properties depending on their structure and composition. Clay minerals are inexpensive and environmentally friendly naturally occurring nanomaterials, thanks to their 1 nm thick silicate layers, in all types of sediments and sedimentary rocks. The book chapters have been classified according to their characteristics in topics and applications. Therefore, in the first section five chapters is dedicated to the characterization and utilization of clay minerals in deposits. The second section includes four chapters about the significance of clay minerals in soils. Third section is devoted to different aspects of clay minerals research, especially to the characterization of structure and modifications for their application.