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Role of Pt in Impedance Based Zeolite Gas Sensors

Title data

Hagen, Gunter ; Dubbe, Andreas ; Moos, Ralf:
Role of Pt in Impedance Based Zeolite Gas Sensors.
Event: Sensor 2007 , 22.-24.05.2007 , Nürnberg, Deutschland.
(Conference item: Conference , Other Presentation type)

Abstract in another language

Hydrocarbon (HC) gas sensors may be helpful for future on-board-diagnostics (OBD) of automotive exhaust gas aftertreatment systems (for example: passenger car OBD legislation requirements for non-methane HCs in 2010-2013). Several methods for HC detection (e.g. conductivity of semiconducting metal oxides, mixed potential principles on solid ion conductors or thermoelectric principles) are possible. A novel way of impedance based sensors utilizing zeolites as ion-conducting functional material is introduced. Such sensors consist of Au interdigital electrodes (IDE), covered by Pt-doped Na-ZSM-5 zeolites.

The microscopic sensing mechanism of the presented sensor setup is not fully elucidated yet, but experimental investigations show that a chromium(III)oxide interface between the Au electrode and the zeolite cover (with no Cr2O3 contact between the interdigital electrodes) is essential. Impedance Nyquist-Plots consist of a high-frequency semicircle, which is attributed to the zeolite ionic mobility, and low-frequency electrode contributions. By admixing of hydrocarbons to a wet oxygen-containing carrier gas flow, the low-frequency complex resistance increases strongly.

Without doubts, effects at the electrode are responsible for the measuring effect. The sensors show a highly selective and sensitive response behavior to HC. There are no cross-sensitivities toward H2 or CO, NO or CO2. This contribution emphasizes that also platinum is a indispensable component for this outstanding effect in addition to Cr2O3 at the interface. It will be shown that it must be present at the interface and also inside the zeolite pores.

Further data

Item Type: Conference item (Other)
Refereed: Yes
Institutions of the University: Faculties > Faculty of Engineering Science
Faculties > Faculty of Engineering Science > Chair Functional Materials > Chair Functional Materials - Univ.-Prof. Dr.-Ing. Ralf Moos
Faculties > Faculty of Engineering Science > Chair Functional Materials
Profile Fields > Advanced Fields > Advanced Materials
Research Institutions > Research Centres > Bayreuth Center for Material Science and Engineering - BayMAT
Profile Fields
Profile Fields > Advanced Fields
Research Institutions
Research Institutions > Research Centres
Result of work at the UBT: Yes
DDC Subjects: 600 Technology, medicine, applied sciences > 620 Engineering
Date Deposited: 09 Jun 2015 07:22
Last Modified: 06 Apr 2016 08:01