Tag Archive for: carbon nanotubes

Publication on AWSensors technology

Interfacial charge storage mechanisms of composite electrodes based on poly(ortho-phenylenediamine)/carbon nanotubes via advanced electrogravimetry

/in , , /by

Authors: El Mahdi Halim, Rezan Demir-Cakan, Hubert Perrot, Mama El Rhazi, Ozlem Sel

Journal: The Journal of Chemical Physics (2022)

 

Abstract

To reach a deeper understanding of the charge storage mechanisms of electrode materials is one of the challenges toward improving their energy storage performance. Herein, we investigate the interfacial ion exchange of a composite electrode made of carbon nanotube/poly( ortho-phenylenediamine) (CNT/P oPD) in a 1M NaCl aqueous electrolyte via advanced electrogravimetric analyses based on electrochemical quartz crystal microbalance (EQCM). Classical EQCM at different scan rates of the potential revealed the complex electrogravimetric behavior likely due to multi-species participation at different temporal scales. Thereafter, in order to better understand the behavior of each species (ions, counter ions, and co-ions) in the charge compensation mechanism, the electrogravimetric impedance spectroscopy analysis (also called ac-electrogravimetry) was pursued. Ac-electrogravimetry revealed the role of each species where Na + cations and Cl − anions as well as protons participate in the charge compensation mechanism of the CNT/P oPD composite with different kinetics and proportions. The water molecules with opposite flux direction with the cations are also detected, suggesting their exclusion during cationic species transfer. Having analyzed ac-electrogravimetry responses in depth, the synergistic interaction between the CNT and P oPD is highlighted, revealing the improved accessibility of species to new sites in the composite.

 

You may read the full paper here.

Scientific publication

Ion Dynamics at the Carbon Electrode/Electrolyte Interface: Influence of Carbon Nanotubes Types

/in , , /by

Authors: Freddy Escobar-Teran, Hubert Perrot and Ozlem Sel.
Journal: Materials (2022)

 

Abstract

Electrochemical quartz crystal microbalance (EQCM) and AC-electrogravimetry methods were employed to study ion dynamics in carbon nanotube base electrodes in NaCl aqueous electrolyte. Two types of carbon nanotubes, Double Wall Carbon Nanotube (DWCNT) and Multi Wall Carbon Nanotube (MWCNT), were chosen due to their variable morphology of pores and structure properties. The effect of pore morphology/structure on the capacitive charge storage mechanisms demonstrated that DWCNT base electrodes are the best candidates for energy storage applications in terms of current variation and specific surface area. Furthermore, the mass change obtained via EQCM showed that DWCNT films is 1.5 times greater than MWCNT films in the same potential range. In this way, the permselectivity of DWCNT films showed cation exchange preference at cathode potentials while MWCNT films showed anion exchange preference at anode potentials. The relative concentration obtained from AC-electrogravimetry confirm that DWCNT base electrodes are the best candidates for charge storage capacity electrodes, since they can accommodate higher concentration of charged species than MWCNT base electrodes.

You may read the full paper here.

Gravimetric and dynamic deconvolution of global EQCM response of carbon nanotube based electrodes by Ac-electrogravimetry

/in , /by

Authors: F. Escobar-Teran, A. Arnau, J.V. García, Y. Jiménez, H. Perrot, O. Sel

Journal: Electrochemistry communications (2016)

The capacity charge storage of carbon nanotube (CNT) based electrodes was investigated by ac-electrogravimetry which couples fast quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS). In contact with an aqueous NaCI electrolyte, evidence was found that there are two types of cations (Na+.H2O and H+) electroadsorbed with different kinetics for cathodic potentials and the Cl– ionsfor anodic potentials together with free water molecules. The reconstruction of the total mass response from independent ac-electrogravimetry measurements agrees perfectly well with the global EQCM response. Our findings reveal the unique sensitivity of the ac-electrogravimetry to provide a fair gravimetric and dynamic deconvolution of the global EQCM responses.

You may read the full paper here