Interaction of multi-walled carbon nanotubes with perfluorinated sulfonic acid ionomers and surface treatment studies

On the use of Nafion® in electrochemical studies of carbon supported oxygen reduction catalysts in aqueous media

“…The self-assembly hypothesis seems to remain at odds with the conclusion reached by Ma et al [37] and by Ma Andersen et al [38] that Nafion® adsorption on Vulcan from low concentrated aqueous solutions is governed by the Langmuir isotherm. In principle, different solvents used by the authors of references [37,38] (water) and by us (IPA) might be responsible for this discrepancy. However, Nafion® molecules are complex entities, which participate in a variety of interactions involving their polar (ether and sulfonic) and non-polar (perfluorinated backbone) groups.…”

“…In absence of such interactions, the adsorption would be described by Langmuir isotherm, which predicts a straight linear increase in Θ/(1 − Θ) with Nafion® concentration [49]. The self-assembly hypothesis seems to remain at odds with the conclusion reached by Ma et al [37] and by Ma Andersen et al [38] that Nafion® adsorption on Vulcan from low concentrated aqueous solutions is governed by the Langmuir isotherm. In principle, different solvents used by the authors of references [37,38] (water) and by us (IPA) might be responsible for this discrepancy.…”

“…However, the ability of Nafion® to act as a surfactant indicates the existence of specific interactions between the catalyst/support particles and the ionomer. In fact, a strong monolayer Nafion® adsorption from liquid solutions on a variety of carbon supported Pt catalysts and catalyst supports has been demonstrated [37][38][39][40][41]. While the respective catalyst activities have not been reported [37][38][39][40], the voltammograms of carbon nanotube (CNT) supported Pt catalysts in Ref.…”

Nano carbon supported platinum catalyst interaction behavior with perfluorosulfonic acid ionomer and their interface structures

“…Representative CVs are shown in figure 8. In the electrodes contain Nafion ionomer, figure 8 (c & d), both hydrogen adsorption and desorption peaks were found to shift slightly towards lower potential in comparison to the electrodes without the ionomer.This is probably due to the fact that platinum and carbon support are covered with the ionomer (due to their strong affinity 27,28,30 ), which might affect the hydrogen adsorption. Therefore, a smaller over-potential is required for adsorption and desorption.Furthermore, less distinct peaks for hydrogen adsorption and desorptionwere observed.…”

Preparation and properties of high-performance poly(amide–imide) composite films based on glucose-functionalized multiwalled carbon nanotubes

“…14 With strong van der Waals attractions between the nanotubes as well as their high aspect ratio and flexibility, they are typically held together as bundles and tend to exist as aggregates when mixed with a polymer matrix. 15 For unfunctionalized CNTs, weak van der Waals attraction between the matrix and the nanotubes is mainly responsible for slightly higher nanotube-polymer interfacial shear stress. Surface treatment of CNTs improves both the dispersion of nanotubes and their adhesion to the polymer matrix due to creation of functional groups on the surface of nanotube.…”