Simultaneous Adsorption–Desorption Processes in the Conductance Transient of Anatase Titania for Sensing Ethanol: A Distinctive Feature with Kinetic Perception

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• 作者：Priyanka Das ; Biswanath Mondal ; Kalisadhan Mukherjee
• 刊名：Journal of Physical Chemistry C
• 出版年：2017
• 出版时间：January 19, 2017
• 年：2017
• 卷：121
• 期：2
• 页码：1146-1152
• 全文大小：540K
• ISSN：1932-7455

文摘

A distinctive feature in the operating temperature-dependent conductance transients of titania sensor is identified during chemi-resistive type detection of ethanol vapor. Precisely, simultaneous adsorption of ethanol and desorption of the corresponding oxidized product over anatase titania sensor are reflected systematically in the response transients measured with the rise in operating temperature. An attempt is made here to understand the origin of the said feature based on the reaction sequences of ethanol over sensor surface. For a fixed ethanol concentration (200 ppm), the conductance transients obtained for response process are modeled using Langmuir–Hinshelwood reaction mechanism and the characteristic time constants are estimated for adsorption and desorption of ethanol. From the temperature variations of these characteristic time constants, the activation energies for the adsorption and desorption of ethanol over sensor surface is estimated. In addition, the general ethanol sensing characteristics (response %, response time, etc.) of the anatase titania is also reported by varying the ethanol concentration (50–500 ppm) and sensor operating temperature (275–375 °C).