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4th Edition of

Chemistry World Conference

June 17-19, 2024 | Paris, France

Chemistry 2023

Saud Asif Ahmed

Speaker at Chemistry World Conference 2023 - Saud Asif Ahmed
Nanjing University, China
Title : Ammonia induced anomalous ion transport in covalent organic framework nanochannels


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 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 (FET) for controlling and modulating the anomalous transport. Our results show that ammonia, a weak base, causes a continuous supply of ions inside 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 the qualities of a nano-sensor.

Audience Take Away:

  • Does this provide a practical solution to a problem that could simplify or make a designer’s job more efficient? 
  •  Mass transport of ions and molecules in nanochannels has attracted much attention due to the emergence of anomalous transport behavior, which is distinctive from the bulk systems. In the hope of controlling and modulating the anomalous transport, efforts have been made to understand its mechanism and the affecting factors to help explore and develop further applications. Exploring the anomalous transport behavior will also pave the way for imitating biological systems' ionic and molecular transport processes. Therefore, transport phenomena in nanochannels are critical research topics requiring in-depth study.
  • Will it improve the accuracy of a design, or provide new information to assist in a design problem? 
  • Theta pipette (TP) or dual-channel pipette has two barrels separated by a band of glass. TP have often been utilized for gas sensing, probing ionic reactions by creating a liquid-liquid interface between aqueous-organic solutions, and field-effect transistor (FET) sensor for single-molecule detection. However, the above-mentioned applications require an interface to limit the movement of ions between barrels or use one of the barrels as a gating electrode, therefore limiting the potential of TP. Furthermore, there is a lack of study to create a nanoconfinement that connects both barrels and the bulk for sensing. So yes, our design can help utilize the full potential of the TP.
  • List all other benefits.
  • The findings of this work can help understand and manipulate the anomalous ion transport behavior in nanochannels, which is essential for biological systems and the field of energy. Furthermore, the findings of this work can also help in designing FET nanodevices for label-free sensing in the bulk solution.


Dr. Saud Asif Ahmed obtained his Ph.D. degree in Analytical Chemistry from Nanjing University, Nanjing, China, in 2020, under the supervision of Prof. Xing-Hua Xia and Prof Kang Wang. Later, he worked as a post-doctoral fellow in the same research group till 2022. He has joined Prof. Ping Yu and Prof. Lan-Qun Mao's research group as a Junior Research Fellow of the Beijing National Laboratory for Molecular Sciences (BNLMS) at the Institute of Chemistry, Chinese Academy of Sciences, Beijing, China. His research mainly focuses on electroanalytical chemistry, electrochemical sensing, and the mass transport of ions through porous materials using single and double-barrel nanopipettes. He has published more than 14 research articles in SCI journals.