A review of the electronic and structural properties of titanium dioxide photocatalysts for the removal of environmental pollutants from wastewater

Today, the treatment of environmental pollutants (textile dyes and wastewater from pharmaceutical wastes) has become one of the most challenging issues, and several methods have been used to treat wastewater, including chemical, physical, and biological methods, each of these methods has its own advantages and disadvantages. In recent decades, titanium dioxide has created suitable conditions for environmental applications due to its unique chemical and physical properties. The basis of photocatalysis processes is based on the production of highly active species such as hydroxyl radicals, which quickly oxidize a wide range of organic pollutants. Titanium dioxide as a semiconductor is an efficient photocatalyst which has been used for oxidation of organic compounds, detoxification, regeneration of toxic metals, effective removal of heavy metals, destruction of bacteria and viruses. Since titanium dioxide and many other semiconductors have a large band gap, the use of photocatalytic water treatment using titanium dioxide is limited due to its relatively low efficiency. In order to improve the photocatalytic efficiency of titanium dioxide for water purification, as well as other photocatalytic applications, a lot of research has been done to extend the photocatalytic response of titanium dioxide to the visible range. In this article, titanium dioxide is systematically introduced and its electronic and structural properties are investigated.