Oxygen Optical Sensing in Gas and Liquids with Nanostructured ZnO Thin Films Based on Exciton Emission Detection

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• 作者：Juan Ram贸n Sanchez-Valencia ; Mar铆a Alcaire ; Pablo Romero-G贸mez ; Manuel Macias-Montero ; Francisco J. Aparicio ; Ana Borras ; Agustin R. Gonzalez-Elipe ; Angel Barranco
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：May 8, 2014
• 年：2014
• 卷：118
• 期：18
• 页码：9852-9859
• 全文大小：401K
• 年卷期：v.118,no.18(May 8, 2014)
• ISSN：1932-7455

文摘

Transparent nanocolumnar porous ZnO thin films have been prepared by plasma-enhanced chemical vapor deposition. By controlling the H₂/O₂ ratio in the plasma gas, the deposition conditions were optimized to obtain an intense exciton emission at around 381 nm and virtually no luminescence in the visible region associated with electronic states in the gap. The intensity of the exciton band varied significantly and reversibly with the partial pressure of oxygen in the environment. This behavior and its variations with temperature and water vapor sustain the use of these thin films as photonic sensors of oxygen. Further experiments in liquid water show that fluorescence intensity also varies with the amount of dissolved oxygen even for concentrations lower than 0.02 mg/L where commercial oxygen galvanic sensors show limited sensitivity. These results and the use of ZnO as photonic sensor of oxygen are discussed by assuming a classical mechanism involving the photoactivated adsorption of oxygen when this oxide is irradiated with UV light during its fluorescence interrogation.