ABSTRACT
Photoelectrochemically active materials could also find their application in environmental remediation by the use of heterogeneous photocatalysis. Basically the discovery of photo-splitting of water using semiconductor photocatalysis by K. Honda and A. Fujishima in 1972 led to the use of photocatalysis for environmental cleaning. Early reports of photocatalytic water treatment were published during 1969-1977 and they demonstrated that toxic and hazardous pollutants such as phenols, cyanides, or polychlorinated biphenyls could be broken down to less hazardous products by semiconductor photocatalysis. During the 1990s, the revolution of nanotechnology brought about a sea change in the field of photocatalysis. Most of the laboratory-scale studies on photocatalysts used suspension-based batch reactors. Reduction in size of conventional bulk semiconductors not only drastically increased the catalytic surface area but also manifested unexpected properties. It could, in turn, overcome the disadvantages of photocatalyst films. The small industry sector has to be educated about the limitations of the conventional technologies compared to solar photocatalytic process.
