Nanosized Photocatalysts in Environmental Remediation

Abstract

We review the science and technology underlying the synthesis of nanosized photocatalysts and their application in environmental remediation. Certain types of semiconductor nanoparticles in both dispersed and supported form can oxidize toxic organic chemicals in liquid, gas and solid phases. This mineralization process can be driven by light and an optimized process can function under ambient conditions of temperature and pressure, producing CO 2 and dilute mineral acids. Such photocatalysis is a potentially inexpensive alternative to other methods for destroying both chemical and biological toxins in the environment. Our review includes discussion of several nanosized photocatalysts with an emphasis on the metal oxide TiO 2 and metal sulfides, especially MoS 2 . We discuss their characterization and the factors which influence their photocatalytic activity and selectivity. Issues such as control of size, quantum confinement, surface chemistry and carrier recombination rate play an important role in the functioning of these photocatalysts. Finally, we summarize some recent applications of TiO 2 films in environmental remediation technology which are just being commercialized. We also discuss future research needs in this area required for an economically viable technology.