Impedimetric Detection of Ammonia and Low Molecular Weight Amines in the Gas Phase with Covalent Organic Frameworks

Abstract

Two Covalent Organic Frameworks (COF), named TFP-BZ and TFP-DMBZ, were synthesized using the imine condensation between 1,3,5-triformylphloroglucinol (TFP) with benzidine (BZ) or 3,3-dimethylbenzidine (DMBZ). These materials were deposited, such as films over interdigitated electrodes (IDE), by chemical bath deposition, giving rise to TFP-BZ-IDE and TFP-DMBZ-IDE systems. The synthesized COFs powders were characterized by Powder X-Ray Diffraction (PXRD), Fourier Transform Infrared spectroscopy (FT-IR), solid-state Nuclear Magnetic Resonance (ssNMR), nitrogen adsorption isotherms, Scanning Electron Microscopy (SEM), and Raman spectroscopy, while the films were characterized by SEM and Raman. Ammonia and low molecular weight amine sensing were developed with the COF film systems using the impedance electrochemical spectroscopy (EIS). Results showed that the systems TFP-BZ-IDE and TFP-DMBZ-IDE detect low molecular weight amines selectively by impedimetric analysis. Remarkably, with no significant interference by other atmospheric gas compounds such as nitrogen, carbon dioxide, and methane. Additionally, both COF films presented a range of sensitivity at low amine concentrations below two ppm at room temperature.

Covalent-organic framework film: From synthesis and structure to energy, catalysis and sensor applications

“…The adjustable structures of COF film can be changed on organic ligands to get more specific responses. [40][41][42][43] Comparing with bulk/powder materials, COF film has larger dimensions and thinner thickness, which is easy to achieve more sensitive response.…”

Recent Advances in Gas Detection Methodologies with a Special Focus on Environmental Sensing and Health Monitoring Applications─A Critical Review

“…Both synthesized COFs showed better electrochemical sensor output toward ammonia and low molecular weight amines due to the physical structure of COFs. It is well-known that COF has a porous cage-like structure which can capture gases onto its motif, and hence its intrinsic electrochemical property changes upon gas adsorption, duly captured by EIS in this case …”

“…It is well-known that COF has a porous cage-like structure which can capture gases onto its motif, and hence its intrinsic electrochemical property changes upon gas adsorption, duly captured by EIS in this case. 70 The advancement in the field of point-of-care technology has allowed the evolution of electrochemical sensors, which can be utilized for early disease diagnosis and provide a rapid and robust response. Tremendous progress has been made in the field of breathomics, which allows the monitoring of endogenously generated VOCs and inorganic gases.…”

Enhanced Sensitivity of Electrochemical Sensors for Ammonia-Nitrogen via In-Situ Synthesis PtNi Nanoleaves on Carbon Cloth

“…At present, the traditional analysis methods of ammonia nitrogen include Nessler’s reagent method, the distillation titration method and spectrophotometry [ 5 , 6 , 7 , 8 ]. Although the above methods had excellent selectivity and sensitivity, they also had disadvantages such as cumbersome operation and long time, so that they are not suitable for the rapid and real-time monitoring of ammonia nitrogen [ 9 ]. Therefore, electrochemical methods with simple operation, fast detection and high sensitivity have gradually attracted the attention of researchers [ 10 ].…”