Abstract
Measurement by impedance spectroscopy of the changes in intrazeolitic cation motion of pressed pellets of zeolite particles upon adsorption of dimethylmethylphosphonate (DMMP) provides a strategy for sensing DMMP, a commonly used simulant for highly toxic organophosphate nerve agents. In this work, two strategies for improving the impedance spectroscopy based sensing of DMMP on zeolites were investigated. The first one is the use of cerium oxide (CeO2) coated on the zeolite surface to neutralize acidic groups that may cause the decomposition of DMMP, and results in better sensor recovery. The second strategy was to explore the use of zeolite Y membrane. Compared to pressed pellets, the membranes have connected supercages of much longer length scales. The zeolite membranes resulted in higher sensitivity to DMMP, but recovery of the device was significantly slower as compared to pressed zeolite pellets.
Highlights
Developing detection strategies for complex chemical species, such as chemical warfare agents (CWAs) is an active area of research [1,2,3,4,5,6,7,8,9,10,11]
The “jumping” rate of the cations was facilitated by the reorientation of the DMMP molecule, leading to the decreased impedance when the sensor is exposed to DMMP
The zeolite membrane surface morphology was investigated by scanning electron microscopy (SEM) (JEOL JSM-5500, JEOL, Tokyo, Japan and Sirion FEG, FEI Company, Tustin, CA, USA) on gold-coated specimens
Summary
Developing detection strategies for complex chemical species, such as chemical warfare agents (CWAs) is an active area of research [1,2,3,4,5,6,7,8,9,10,11]. Kim et al found that the metal oxide based sensors had poor recovery, possibly due to the strong adsorption of the products from the decomposition of the analyte molecules on the oxide surfaces [10,11]. Since these chemoresistive gas sensors use the change in electronic resistance induced by the redox reactions between the adsorbed surface oxygen and “targeted” species, selectivity is often a problem. There is a need for development of new sensing materials and transduction mechanisms for detection of CWAs [1,4]. Thin membranes of zeolite Y have been explored for the first time for impedancebased sensing
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