Stress-induced chemical detection using flexible metal-organic frameworks.

Allendorf, Mark D. ; Hesketh, Peter J. (Georgia Institute of Technology, Atlanta, GA) ; Gall, Kenneth A. (Georgia Institute of Technology, Atlanta, GA) ; Choudhury, A. (Georgia Institute of Technology, Atlanta, GA) ; Pikarsky, J. (Georgia Institute of Technol

关键词: ADSORPTION;    ADSORPTION ISOTHERMS;    ATMOSPHERIC PRESSURE;    CRYSTAL STRUCTURE;    DETECTION;    ETHANOL;    EXPLOSIVES;    GASES;    HYDRATION;    HYDROCARBONS;    ISOTHERMS;    METHANOL;    NERVES;    ORGANIC COMPOUNDS;    RAMAN SPECTROSCOPY;    THIN FILMS;    WATER;   

DOI  :  10.2172/993628
RP-ID  :  SAND2009-6185
PID  :  OSTI ID: 993628
Others  :  TRN: US201024%%96

美国|英语

来源: SciTech Connect

【 摘 要 】

In this work we demonstrate the concept of stress-induced chemical detection using metal-organic frameworks (MOFs) by integrating a thin film of the MOF HKUST-1 with a microcantilever surface. The results show that the energy of molecular adsorption, which causes slight distortions in the MOF crystal structure, can be efficiently converted to mechanical energy to create a highly responsive, reversible, and selective sensor. This sensor responds to water, methanol, and ethanol vapors, but yields no response to either N{sub 2} or O{sub 2}. The magnitude of the signal, which is measured by a built-in piezoresistor, is correlated with the concentration and can be fitted to a Langmuir isotherm. Furthermore, we show that the hydration state of the MOF layer can be used to impart selectivity to CO{sub 2}. We also report the first use of surface-enhanced Raman spectroscopy to characterize the structure of a MOF film. We conclude that the synthetic versatility of these nanoporous materials holds great promise for creating recognition chemistries to enable selective detection of a wide range of analytes. A force field model is described that successfully predicts changes in MOF properties and the uptake of gases. This model is used to predict adsorption isotherms for a number of representative compounds, including explosives, nerve agents, volatile organic compounds, and polyaromatic hydrocarbons. The results show that, as a result of relatively large heats of adsorption (> 20 kcal mol{sup -1}) in most cases, we expect an onset of adsorption by MOF as low as 10{sup -6} kPa, suggesting the potential to detect compounds such as RDX at levels as low as 10 ppb at atmospheric pressure.