Nanoporous-Based Sensors for Impedance Spectroscopy-Based Detection of Gaseous Pollutants

The advanced in situ detection of gaseous pollutants (e.g. NOx and SOx) is of great interest in many applications, such as the automotive and coal industries. Here, we leverage the previous successful development of impedance spectroscopy-based sensors for the detection of gaseous I2 to develop a novel sensor for the detection of these gaseous pollutants. During initial development of an I2 sensor, a metal-organic framework (MOF ZIF-8) material was utilized as an adsorbent layer deposited onto Pt interdigitated electrodes. The MOF was demonstrated to selectively adsorb I2, irreversibly, from a complex gas stream with a (>105x) change in measured impedance across the electrodes1. Further studies aimed at developing a robust sensor examined other materials, including zeolites2 and additional MOFs. It was demonstrated that utilizing MFM-300(X) (X= Al, Fe, In or Sc metal center) active materials enabled a reversible electrical response via gas adsorption/desorption3. The current work is focused on exploring these same nanoporous phases (MOFs, zeolites, etc.) for the real-time detection of NOx and SOx. The down-selection of candidate materials from bulk synthesis and gas selectivity testing will be discussed. Methods for deposition of these materials onto the Pt interdigitated electrodes and initial sensor performance during controlled gas exposures will be presented. Acknowledgements Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government. References 1) Small, L.J and Nenoff, T.M., ACS Appl. Mater. Interfaces, 2017, 9 (51), 44649-44655. 2) Small, L.J.; Krumhansl, J.L.; Rademacher, D.X.; Nenoff, T.M. Micro. Meso. Mater., 2019, 280, 82-87. 3) Small, L.J.; Hill, R. C.; Krumhansl, J. L.; Schindelholz, M. E.; Chen, Z.; Chapman, K.W.; Zhang, X.; Yang, S.; Schroder, M.; Nenoff, T.M., ACS Applied Materials and Interfaces, 2019, 11(31), 27982-27988.