Search

Your search keyword '"Phal, Sereilakhena"' showing total 4 results
Start Over Author "Phal, Sereilakhena" Topic grafting
4 results on '"Phal, Sereilakhena"'

1. Oxygen Interactions with Covalently Grafted 2D Nanometric Carboxyphenyl Thin Films—An Experimental and DFT Study.

Author

Haziri, Veton, Phal, Sereilakhena, Boily, Jean-François, Berisha, Avni, and Tesfalidet, Solomon

Subjects
THIN films, X-ray photoelectron spectroscopy, MATERIALS science, GOLD, GOLD electrodes, CYCLIC voltammetry
Abstract

Surface modification is a hot topic in electrochemistry and material sciences because it affects the way materials are used. In this paper, a method for covalently attaching carboxyphenyl (PhCOOH) groups to a gold electrode is presented. These groups were grafted onto the electrode surface electrochemically via reduction of aryldiazonium salt. The resulting grafted surface was characterized using cyclic voltammetry (CV) before and after the functionalization procedure to validate the presence of the grafted layer. The grafting of PhCOOH groups was confirmed by analyzing electrode thickness and composition by ellipsometry and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) calculations indicated that the grafted layers provide a stable platform and resolved, for the first time, their interactions with oxygen. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

2. Electrografting of 4-Carboxybenzenediazonium on Glassy Carbon Electrode: The Effect of Concentration on the Formation of Mono and Multilayers.

Author

Phal, Sereilakhena, Shimizu, Kenichi, Mwanza, Daniel, Mashazi, Philani, Shchukarev, Andrey, Tesfalidet, Solomon, and Little, R. Daniel

Subjects
*MULTILAYERS, *CARBON electrodes, *X-ray photoelectron spectroscopy, *CYCLIC voltammetry, *DIAZONIUM compounds, *MOIETIES (Chemistry)
Abstract

Grafting of electrodes with diazonium salts using cyclic voltammetry (CV) is a well-established procedure for surface modification. However, little is known about the effect of the concentration of the diazonium salt on the number of layers grafted on the electrode surface. In this work, the impact of concentration on the grafting of 4-carboxybenzenediazonium (4-CBD) onto a glassy carbon electrode (GCE) is elucidated. The number of layers grafted on the GCE was linearly dependent on the concentration of 4-CBD and varied between 0.9 and 4.3 when the concentration was varied between 0.050 and 0.30 mmol/L at 0.10 V.s−1. Characterization of modified glassy carbon surface with X-ray photoelectron spectroscopy (XPS) confirmed the grafting of carboxyphenyl layer on the surface. Grafting with 0.15 mmol/L 4-CBD (1 CV cycle) did not form a detectable amount of carboxyphenyl (CP) moieties at the surface, while a single scan with higher concentration (2.5 mmol/L) or multiple scans (22 cycles) gave detectable signals, indicating formation of multilayers. We also demonstrate the possibility of removing the thin layer grafted on a glassy carbon electrode by applying high oxidation potential +1.40 V. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

3. Grafting of the Gold Surface by Heterocyclic Moieties Derived through Electrochemical Oxidation of Amino Triazole: An Experimental and Ab Initio Study.

Author

Sheqerxhiu, Nimet, Lajci, Azem, Tesfalidet, Solomon, Phal, Sereilakhena, Sheqerxhiu, Nardi, and Berisha, Avni

Subjects
METALLIC surfaces, GOLD, MOIETIES (Chemistry), TRIAZOLES, OXIDATION
Abstract

Surface modification of gold is accomplished by using the aminyl radicals formed through the electrochemical oxidation of the amino-triazole molecule dissolved in organic media (acetonitrile). The electrochemistry of the grafting process and the redox behavior of the grafted heterocyclic layer is similar to that of the aliphatic amines [1]. The capability of the modified surfaces for blocking redox reaction was assessed using ferrocyanideferricyanide redox couple and displayed important differences. The redox probes display a decrease electron transfer rate. The increase of the charge transfer resistance of the grafted layer is suggestive for a compact layer formation. Furthermore, the Au13 cluster was used to compute BDE (Bond dissociation energies) and a number of other important parameters such as bond strength and length of the interface, etc. These parameters were computed using ONTEP software [Order-N Total Energy Package - a software intended specifically for calculations on large systems, it employs density functional theory (DFT) in the density matrix formulation. [ABSTRACT FROM AUTHOR]

Published
2019

4. Electrochemical Grafting of Heterocyclic Amines on the Gold Surface.

Author

Sheqerxhiu, Nimet, Lajci, Azem, Tesfalidet, Solomon, Phal, Sereilakhena, Sheqerxhiu, Nardi, and Berisha, Avni

Subjects
AMINES, METALLIC surfaces, GOLD electrodes, AMINYL radicals, CYCLIC voltammetry
Abstract

The electrochemical properties of Au electrode grafted with amino-triazole (AT) groups have been studied. In the first step, gold electrode was covalently grafted with a layer of AT via the formation of aminyl radicals under electrochemical oxidation reaction of corresponding AT molecule. The surface modification of gold electrode via aminyl radicals is initiated by using cyclicvoltammetry (several scan cycles in the potential range +0.2 and +1.6 V) through the electro-oxidation of AT solution in acetonitrile. The presence of AT groups on the modified electrode surface was studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and compared with the electrochemical behaviour of the bare gold. The barrier proprieties of the deposited layer on the gold surface was investigated in the presence of an electroactive Fe(CN)63-/4- redox probe. The results indicate the presence of the amino-triazole groups on the gold surface - confirming a successful grafting reaction. [ABSTRACT FROM AUTHOR]

Published
2019

Catalog

Books, media, physical & digital resources
See catalog results