Nano Archive

Photoreactivity of ZnO nanoparticles in visible light: Effect of surface states on electron transfer reaction

Baruah, Sunandan and Sinha, Sudarson Sekhar and Ghosh, Barnali and Pal, Samir Kumar and Raychaudhuri, A. K. and Dutta, Joydeep (2009) Photoreactivity of ZnO nanoparticles in visible light: Effect of surface states on electron transfer reaction. Journal of Applied Physics . ISSN 0021-8979

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Abstract

Wide band gap metal oxide semiconductors such as zinc oxide (ZnO) show visible band photolysis that has been employed, among others, to degrade harmful organic contaminants into harmless mineral acids. Metal oxides show enhanced photocatalytic activity with the increase in electronic defects in the crystallites. By introducing defects into the crystal lattice of ZnO nanoparticles, we observe a redshift in the optical absorption shifting from the ultraviolet region to the visible region (400–700 nm), which is due to the creation of intermediate defect states that inhibit the electron hole recombination process. The defects were introduced by fast nucleation and growth of the nanoparticles by rapid heating using microwave irradiation and subsequent quenching during the precipitation reaction. To elucidate the nature of the photodegradation process, picosecond resolved time correlated single photon count (TCSPC) spectroscopy was carried out to record the electronic transitions resulting from the de-excitation of the electrons to their stable states. Photodegradation and TCSPC studies showed that defect engineered ZnO nanoparticles obtained through fast crystallization during growth lead to a faster initial degradation rate of methylene blue as compared to the conventionally synthesized nanoparticles.

Item Type:Article
Subjects:Material Science > Nanofabrication processes and tools
ID Code:8751
Deposited By:CSMNT
Deposited On:27 Mar 2010 09:04
Last Modified:27 Mar 2010 09:04

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