Titanium dioxide in photocatalysis

Abstract

TiO2-based heterogeneous photocatalysis is a process that develops rapidly in environmental engineering and it is now employed in several industrial domains, including water treatment, air purification, and self-cleaning surfaces. Photocatalysis is a natural phenomenon in which the TiO2 accelerates a chemical reaction through the action of light, without being altered. The illuminated TiO2 induces the formation of reactive species, able to decompose by oxidation and/or reduction reactions organic or inorganic substances. The major part of the applications of photocatalysis corresponds to organic oxidation, and it is now considered as one of the Advanced Oxidation Technologies (AOTs), gathering the reactions mainly based on hydroxyl radical (HO•) chemistry. The development of a system based on photocatalysis requires gathering knowledge of numerous and various scientific domains: physical-chemistry, materials science, catalysis, environmental chemistry, biology, and engineering science. This chapter is therefore designed to give a detailed survey of the different scientific fields concerning TiO2-based photocatalysis. Various aspects are developed: materials (synthesis, crystal chemistry, electronic and optical properties of TiO2), physical-chemistry (photon absorption, charge-carrier dynamics, surface adsorption, and photooxidation mechanisms), environmental chemistry (dyes, pesticides, bacteria, and antibiotic photodegradation, real industrial wastewater treatment), and engineering (photocatalytic reactor design and simulation).