Electrical Detection of Gaseous Pollutants Using Nanoporous-Based Gas Sensors

The advanced in situ detection of gaseous pollutants, such as NOx or SOx, is of great interest in many applications, such as the automotive and coal industries. We will discuss the continued advancement of our low power sensors for these pollutants, leveraging the previous successful development of impedance spectroscopy-based sensors for the detection of gaseous I2.1-3 The sensors, composed of Pt interdigitated electrodes (IDEs) with a nanoporous adsorbent layer, can be tuned to selectively adsorb gases of interest through judicious material selection, and the electrical response directly correlated to gas concentration. The current work is focused on exploring these nanoporous phases (metal-organic frameworks (MOFs), zeolites, etc.) for the real-time detection of NOx. The sensors have been successfully demonstrated for detection of trace NO2 (0.5 – 5 ppm),4 and experimental results, collected at relatively low temperature (25-50°C), will be discussed. Other recent work exploring the direct growth of crystalline MOF membranes, through the chemical functionalization of the surface of interdigitated electrodes will also be discussed.5 Direct growth of thin MOF films on surface functionalized IDEs has been shown to result in increased sensor sensitivity and a faster response time. Lastly, we will present initial results for the use of the sensors in the selective detection of NO2 in complex environments (e.g. presence of H2O, CO2, etc.).6 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 Small, L.J and Nenoff, T.M., ACS Appl. Mater. Interfaces, 2017, 9 (51), 44649. Small, L.J.; Krumhansl, J.L.; Rademacher, D.X.; Nenoff, T.M. Meso. Mater., 2019, 280, 82. 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. Small, L.J.; Henkelis, S.E; Rademacher, D.X.; Schindelholz, M. E.; Krumhansl, J. L.; Vogel, D.J.; Nenoff, T.M, Advanced Functional Materials, 2020, 30 (50), 2006598. Henkelis, S.E; Percival, S.J.; Small, L.J; Rademacher, D.X.; Nenoff, T.M, Membranes, 2021, 11 (3), 176. Percival, S.J.; Henkelis, S.E; Li, M.; Schindelholz, M.E.; Krumhansl, J. L.; Small, L.J.; Lobo, R.F.; Nenoff, T.M., I Eng. Chem. Res., 2021, 60 (40), 14371.