Marie-Laure Bocquet (UMR PASTEUR, ENS) présentera mercredi 8 novembre à 14h, dans la salle des Conseils de la faculté de Chimie (32.42.101), un séminaire intitulé :
Mild chemistry on graphene interfaces : a first-principles investigation in vacuum and in water
Abstract
Graphene is an attractive candidate for carbon-based electronic devices. However the absence of band gap is a major hindrance for such application. So there is a need to develop routes for engineering the band gap via chemical covalent functionalizations. The challenge resides in the fact that graphene is assumed to be chemically inert. Hence covalent functionalization requires drastic conditions that affect the ideality of pristine graphene.
In this talk I will first question whether cycloaddition reactions between porphyrins and graphene prototyping mild chemistry is a viable route.
Based on an extensive static DFT study we unveiled the necessity of pre-activating the graphene layer via epitaxy on a proper metallic substrate. In particular we showed that the feasibility of the cycloaddition between an iron-porphine and epitaxial graphene strongly depends on the nature of the metal, Ir being the most active support as compared to Re and Cu. [1] Such predictive cycloaddition process has been realized at the single-molecule level by STM-induced chemistry on low-coverage iron phthalocyanine (FePc) molecules adsorbed on graphene on Ir. [2]
Finally I will question the chemical inertness of graphene in a water media. Recent nanofluidic experiments have demonstrated the significant charging capacity of carbon nanotubes of diameters ranging from 7nm to 70 nm in alkaline water for promising applications in « blue energy ». [3] Static DFT calculations in vacuum and implicit water contradict the charging via chemisorption of hydroxide ions on single layer graphene. [4]. However our recent AIMD simulations with explicit water solvent permit to reconcile the atomistic quantum simulations with the experiments.
References
[1] M. Lattelais, M.L. Bocquet, Journal of Physical Chemistry C, 119, 9234−9241 (2015).
[2] S. J. Altenburg, M. Lattelais, B. Wang, M.−L. Bocquet, and R. Berndt., J. Am. Chem. Soc, 137, 9452−9458 (2015).
[3] Secchi E, Niguès A, Jubin L, Siria A, Bocquet L, Physical Review Letters, 116 154501 (2016).
[4] Grosjean B, Péan C, Siria A, Bocquet L, Vuilleumier R, Bocquet M-L, Journal of Physical Chemistry Letters, 7, 4695-4700 (2016).
