Paramagnetic point defects sensitive to the surrounding atmosphere were observed in ZnO powder. Changes in EPR lines following either thermal-vacuum treatment or contact with molecular O2 led to definite conclusions regarding the nature of the ZnO point defects and the electron-transfer processes active at the ZnO/O2 interface. Two different point defects are identified: A (gA = 1.955), assigned to ionized interstitial zinc centres Zni+, and B (gB = 1.958), assigned to ionized oxygen vacancies vo+. Both are able to reduce molecular oxygen, but only vo+ defects give rise to O2-. ZnO-supported ruthenium was also investigated: dispersed Ru improves the electron transfer from the oxide to the O2 molecules of the surrounding atmosphere.
Morazzoni, F., Scotti, R., Volonte, S. (1990). ELECTRON-PARAMAGNETIC RESONANCE INVESTIGATION OF PARAMAGNETIC POINT-DEFECTS IN ZNO AND ZNO-SUPPORTED RUTHENIUM. JOURNAL OF THE CHEMICAL SOCIETY. FARADAY TRANSACTIONS, 86(9), 1587-1591 [10.1039/ft9908601587].
ELECTRON-PARAMAGNETIC RESONANCE INVESTIGATION OF PARAMAGNETIC POINT-DEFECTS IN ZNO AND ZNO-SUPPORTED RUTHENIUM
MORAZZONI, FRANCA;SCOTTI, ROBERTO;
1990
Abstract
Paramagnetic point defects sensitive to the surrounding atmosphere were observed in ZnO powder. Changes in EPR lines following either thermal-vacuum treatment or contact with molecular O2 led to definite conclusions regarding the nature of the ZnO point defects and the electron-transfer processes active at the ZnO/O2 interface. Two different point defects are identified: A (gA = 1.955), assigned to ionized interstitial zinc centres Zni+, and B (gB = 1.958), assigned to ionized oxygen vacancies vo+. Both are able to reduce molecular oxygen, but only vo+ defects give rise to O2-. ZnO-supported ruthenium was also investigated: dispersed Ru improves the electron transfer from the oxide to the O2 molecules of the surrounding atmosphere.
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