Surface modification of TiO2 nanoparticles with AHAPS aminosilane: distinction between physisorption and chemisorption - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Adsorption - Journal of the International Adsorption Society Année : 2013

Surface modification of TiO2 nanoparticles with AHAPS aminosilane: distinction between physisorption and chemisorption

Résumé

This paper addresses the surface modification of TiO2 nanoparticles with n-(6-aminohexyl)aminopropyltrimethoxysilane (AHAPS) using various initial aminosilane concentrations. The main objective of this article is to show experimentally the importance of the physisorption during the grafting process. The distinction between chemisorbed and physisorbed aminosilane molecules on TiO2 is thoroughly analyzed. The surface of bare and modified TiO2 particles has been characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) to gain a better understanding of the adsorption mechanism of AHAPS on TiO2. Quantitative information on surface energy of TiO2, in terms of adsorption energy sites and heterogeneity, has been investigated by quasi-equilibrium low-pressure adsorption technique using nitrogen and argon as probe molecules. The FTIR and XPS data are combined to estimate and discuss the chemisorbed and physisorbed contribution. The results demonstrate that both physisorption and chemisorption occurs but they display a different behavior. The physisorbed amounts are much higher than the chemisorbed amounts. This shows that the main part of the adsorbed layer is composed of physisorbed molecules. The physisorbed uptake depends highly on the AHAPS concentration while the chemisorbed amount remains constant. Quasi-equilibrium Ar derivative adsorption isotherms reveal that the AHAPS molecules are mostly located on the {101} and {001} faces of titania and that the two faces display the same reactivity toward AHAPS sorption. Nitrogen adsorption experiments show that the sorption takes place on the three polar surface sites of high energy. The molecules are chemisorbed onto the site displaying the highest energy while they are physisorbed on the two lower energy sites.

Dates et versions

hal-01115234 , version 1 (10-02-2015)

Identifiants

Citer

Mounir Kassir, Thibault Roques-Carmes, Tayssir Hamieh, Angelina Razafitianamaharavo, Odile Barres, et al.. Surface modification of TiO2 nanoparticles with AHAPS aminosilane: distinction between physisorption and chemisorption. Adsorption - Journal of the International Adsorption Society, 2013, 19 (6), pp.1197-1209. ⟨10.1007/s10450-013-9555-y⟩. ⟨hal-01115234⟩
149 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More