Team
- Permanent members: Michel Goldmann
- PhD student: Alexia Bintintzanos
Graphene and ionic liquids are intensively studied, respectively as electrolyte and as electrode materials, for the development of supercapacitors. In this framework, the characterization between the two species is essential. We realized such kind of interfaces through the Langmuir film procedure and characterized them at different scales. We studied films formed by different ionic liquids, by graphene oxide and finally by a mixture of the two species. The study on the pure ionic liquids evidences the role of the cation on the film organization at the air-water interface, for the monolayer as well as for the tridimensional phase. Moreover, we showed that the pure graphene oxide films are composed of a bilayer of sheets à the interface, even at low surface densities. Finally, regarding the mixed film, we observed a vertical segregation of the species for high enough surface pressures. The film is formed by a first layer in contact with the water surface and composed of mostly vertical ionic liquid molecules, on which a second layer is superimposed composed of graphene oxide sheets. At higher compression rates, Ionic Liquid molecules “climb” onto the graphene oxide sheets but are mainly lying parallel to the interface.
Caption: Schematic representation of the GO sheets at the air-water interface. Left link between the GO sheets. Right relative orientation of the GO sheets during the compression (region (i), region (ii) and region (iii)).
Caption: Schematic representations of the ionic liquid and graphene oxide stack configurations at P = 11mN.m–1.
Collaborations
- P. Fontaine (Synchrotron SOLEIL, Gif/Yvette France)
- François Muller (ECE Paris, France )
- E. Filipe (Instituto Superior Tecnico- Lisbon Portugal)
Past PhD
- Nathalie Bonatout “Study of Langmuir films of graphene oxide, ionic liquids and mixed systems”. Defense: November 2017
- Helen Ibrahim, “Study of [C20mim]+[NTf2]- ionic liquid Langmuir films mixed with graphene oxide sheets or deposited on aqueous gold ions subphases and irradiated by grazing incidence X-rays”. Defense: November 2020
Publications
- Eduardo. J. M. Filipe, Pedro Morgado, Miguel Teixeira, Karina Shimizu, Nathalie Bonatout, et al.. Crystalline-like structures and multilayering in Langmuir films of ionic liquids at the air–water interface. Chemical Communications, Royal Society of Chemistry, 2016, 52 (32), pp.5585-5588. ⟨10.1039/c6cc01368f⟩. ⟨hal-01314512⟩
- Nathalie Bonatout, François Muller, Philippe Fontaine, Ignacio Gascon, Oleg Konovalov, et al.. How exfoliated graphene oxide nanosheets organize at the water interface: evidence for a spontaneous bilayer self-assembly. Nanoscale, Royal Society of Chemistry, 2017, 9 (34), pp.12543-12548. ⟨10.1039/C7NR03403B⟩. ⟨hal-01586796⟩
- Abhijeet Ojha, Helen Ibrahim, Natalia Alyabyeva, Remi Lazzari, Michel Goldmann, et al.. Nanosheet size-dependent rheology, microstructure, adsorption properties of graphene oxide-electrolyte dispersions and adsorbents. Synthetic Metals, Elsevier, 2020, 269, pp.116494. ⟨10.1016/j.synthmet.2020.116494⟩. ⟨hal-02995172⟩
