Ammonia-Induced Anomalous Ion Transport in Covalent Organic Framework Nanochannels

Abstract

More anomalous transport behaviors have been observed with the rapid progress in nanofabrication technology and characterization tools. The ions/molecules inside nanochannels can act dramatically different from those in the bulk systems and exhibit novel mechanisms. Here, we have reported the fabrication of a nanodevice, covalent organic frameworks covered theta pipette (CTP), that combine the advantages of theta pipette (TP), nanochannels framework, and field-effect transistors (FETs) for controlling and modulating the anomalous transport. Our results show that ammonia, a weak base, causes a continuous supply of ions inside covalent organic framework (COF) nanochannels, leading to an abnormally high current depending on the ionic/molecular size and the pore size of the nanochannel. Furthermore, CTP can distinguish different concentrations of ammonia and have all of the qualities of a nanosensor.

Iontronic Sensing Based on Confined Ion Transport

“…This interest has led to the discovery of various intriguing ion transport phenomena in confined space, including higher-than-bulk conductance and precise ion selectivity. These distinctive phenomena enable the detection of various analytes, ranging from ions/molecules ,− to nucleic acids and peptides/proteins with high sensitivity and specificity.…”

“…Characterization of Confined Space for Iontronic Sensors. Geometrical characterization of confined space (nanopore/nanochannel) for iontronic sensors is commonly conducted through a combination of microscopic techniques such as transmission electron microscopy (TEM) 126 and scanning electron microscopy (SEM) 127,128 along with electrochemical measurements, 129 involving the recording of electrochemical resistance. TEM imaging proves invaluable for precisely determining pore size and cone angle in small-sized nanopipettes.…”