a brief perspective on photodegradationm mechanisms

In recent past decades, explosive increased in the world population induced critical interests toward environmental and energy issues. thus, introducing/developing novel techniques/catalysts is a critical research filed for analytical/environmental chemists. a common technique in the above mentioned issues is heterogeneous photocatalysis based on the illumination of a typical semiconducting material for inducing photoinduced electrons (e) in the conduction band (cb) and holes (h) in its valence band (vb). other reactive species are powerful hydroxyl and superoxide radicals due to the reaction of the holes with water molecules and the electrons with the dissolved oxygen. the e/h recombination drastically decreases the overall efficiency of the photocatalysis process. an efficient strategy to diminish the e/h recombination is coupling of two or more semiconductors for constructing heterojunction structures. mechanisms suggested for transferring the charge carriers between the contacted semiconductors are commonly type (ii)- heterojunction and direct z-scheme pathways that will illustrate here. commonly, direct z-scheme mechanism produce powerful reducing and oxidizing centers than the second case, and it is more efficient in photocatalysis. water splitting for hydrogen production and oxygen evolution is a use of photocatalysis in energy issue, while degradation and mineralization of organic pollutants is its application in environmental issue.