EPR study on paramagnetic species in nitrogen-doped ZnO powders prepared by a mechanochemical method

• Published in: Chemical physics letters Vol. 436; no. 4; pp. 373 - 377
• Main Authors: Moribe, Shinya, Ikoma, Tadaaki, Akiyama, Kimio, Zhang, Qiwu, Saito, Fumio, Tero-Kubota, Shozo
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 09.03.2007
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/j.cplett.2007.01.067

Nitrogen-doped ZnO (N-ZnO) powders prepared by a mechanochemical method show two kinds of EPR signals due to a singly ionized nitrogen ( N 2 - ) and a shallow donor. Visible light irradiation of the N-ZnO particles reveals a reversible response of reduction of the EPR signal of the N 2 - radical site and an increase due to a shallow donor. Paramagnetic species in nitrogen-doped ZnO (N-ZnO) powders, visible light sensitive photocatalysts exhibiting antibacterial activity, have been investigated using EPR spectroscopy. The N-ZnO photocatalysts showed two kinds of EPR signals due to a singly ionized nitrogen ( N 2 - ) and a shallow donor. Visible light irradiation to the N-ZnO particles shows reversible response of reduction of EPR signal of the N 2 - radical site and increase of that due to shallow donor. The results indicate that the N 2 - is converted to a diamagnetic neutral molecular nitrogen acceptor ( N 2 0 ) by visible light and photoinduced electrons are trapped to the shallow donor sites.