Strategies of making TiO₂ and ZnO visible light active

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• 作者：Shama Rehman ; Ruh Ullah ; A.M. Butt ; N.D. Gohar
• 关键词：Visible light sensitization ; Band gap modification ; Oxygen vacancies ; Impurity states
• 刊名：Journal of Hazardous Materials
• 出版年：2009
• 出版时间：30 October 2009
• 年：2009
• 卷：170
• 期：2-3
• 页码：560-569
• 全文大小：334 K

文摘

In modern purification techniques employing semiconductor mediated photooxidation of toxic substances, zinc oxide (ZnO) and titanium dioxide (TiO₂) are the most widely used metal oxides due to their unique blend of properties. However, the band edges of these semiconductors lie in the UV region which makes them inactive under visible light irradiation. Researchers have been interested in the modification of electronic and optical properties of these metal oxides for their efficient use in water and air purification under visible light irradiation. Visible light activity has been induced in TiO₂ and ZnO by surface modification via organic materials/semiconductor coupling and band gap modification by doping with metals and nonmetals, co-doping with nonmetals, creation of oxygen vacancies and oxygen sub-stoichiometry. This paper encompasses the progress and developments made so far through these techniques in the visible light photocatalysis with TiO₂ and ZnO. Recently, nitrogen doping in titania has been extensively carried out and therefore somewhat detailed discussion in this respect has been presented. Visible light activation of titania clusters encapsulated in zeolite-Y by nitrogen doping and incorporation of dye or organic sensitizers inside the zeolite framework, has also been highlighted in this review.