A simple, reliable, reproducible and efficient method to decorate MWCNTs with different nanoparticles (iron, bismuth oxide, barium oxide, maghemite, nickel hydroxide, and lanthanum hydroxide) is presented. Purified MWCNTs (a novel method involving refluxing MWCNTs in a NaOH solution leads to purified MWCNTs) are first functionalized with aryl diazonium salts generated in-situ, followed by their impregnation and calcination. Four organic molecules were considered for the functionalization: 4-aminobenzoic acid, 5-amino-1,2,3-benzenetricarboxylic acid, 4-aminobenzylphosphonic acid and sulfanilic acid. It is worth to note that the functionalization procedure was carried out at room temperature under IR irradiation without any problem. Different techniques (XPS, TEM, PXRD, FE-SEM, HR-TEM, STEM, TGA, Raman, UV-Vis spectroscopy and EDX) were used to characterize the resulting materials. Obtaining small size homogeneously distributed nanoparticles (<10 nm mostly, sometime around 20 nm and 30 nm are also reported) on MWCNTs is the main achievement of this work. The present methodology is also proved experimentally to prepare materials in large scale (6g at the lab scale but also have potential to be prepared at industrial scale). The effect of surface concentration of functional groups revealed that the higher the number of functional groups, the greater is the anchoring capacity, more crystallinity but slightly size increases (slight agglomeration) due to high available concentration of nanoparticles. For example, tricarboxylic aryl diazonium functions, used for the first time to functionalize CNTs is superior to the monocarboxylic one. Bucky papers electrical conductivity measurement reveals the advantage of diazonium chemistry over acid treatment. The various functions arranged in the order of their increasing anchoring capacities towards metal ions are as follows: sulfonic < carboxylic < phosphonic. Furthermore, the nanocomposites with superior characteristics (synergistic effects) are used for different applications such as dye removal (a common dye pollutant that is methylene blue was considered to evaluate the ability of the present composite for dye removal) and electrochemical sensing for organic molecules. Materials have also been successfully applied for defense applications such as kevlar reinforcement and energetic materials.
|Date of Award||23 Mar 2020|
|Supervisor||Zineb MEKHALIF (Supervisor), Guillaume Berionni (President), Catherine Michaux (Jury), Ouanassa Guellati (Jury) & Mohamed Mehdi Chehimi (Jury)|