TiO2-based Nanomaterials with Photocatalytic Properties for the Advanced Degradation of Xenobiotic Compounds from Water. A Literature Survey

In recent years, the photochemistry of nano-semiconductor particles has been one of the fastest growing research areas in the physical chemistry field. TiO 2 is considered as the most thoroughly investigated semiconductor in the literature, due to its photocatalytic activity, excellent functionality, thermal stability, and non-toxicity. It seems to be the most promising for the photocatalytic destruction of organic pollutants. The challenge for scientific materials is to find a processing method in which the crystalline phase as well as the size and morphology of TiO 2 nanocrystals can be controlled. The concept of the present paper consists of a comprehensive study regarding the level of knowledge in the synthesis of TiO 2 -based nanopowders and their application in the advanced degradation of aromatic nitrocompounds. The objectives are related to: critical analysis of the synthesis techniques of the TiO 2 -based nanopowders, underlining the importance of using the sol–gel method evaluation of the morphological and structural specific characterization of these techniques; and a comprehensive study of the operational parameters of the pollutant photocatalytic degradation. The relative simple sol–gel method is the most widely used, being considered as a versatile means of developing catalytic materials, as well as an important experimental tool in understanding their physical and chemical properties. In order to enhance TiO 2 photocatalysis and to extend the response into the visible domain, titanium has been doped with metals, nonmetals, and ionic components. A recent literature survey concerning some transition metals-doping (Fe, Co, and Ni) of TiO 2 nanopowders by the sol–gel method was also included.