During the last two decades a lot of effort has been devoted to develop a material that could store an applicable amount of hydrogen by physisorption. All these attempts have failed. Therefore, computer simulations have been used to guide the experiment and to determine in advance the potential storage capacity of a particular structure.Usually, to simplify the interaction model and to spare the computation time, the simulations of hydrogen adsorption in nanoporous materials use the superatom representation of H2 molecule with semi-empirical values of interaction model. This approach totally neglects the non-spherical shape of the molecule. However, this information may be crucial for the precise evaluation of the amount stored and the structure of the adsorbed layers, as packing of the spherical and elongated molecules is not the same. Therefore in the present work we compare the structure and storage of H2 in slit-shaped, infinite carbon pores of nanometric width (from 0.6 nm to 2.5 nm), modeled using united atom (UA) and all atom (AA) representation of H2 molecule.We used Grand Canonical Monte Carlo technique to simulate H2 adsorption isotherms at T = 77 K, either within Material Studio software (for AA model) or home-made code (for UA model). We shows that in both models the calculated amount of stored hydrogen is similar. This results confirm the validity of previous UA model-based estimations of storage capacity reported in the literature. Moreover, our simulation shows that UA model slightly overestimates the stored amount in narrowest pores (0.6 – 0.8 nm) and underestimates it in pores of width of 1.0 -1.2 nm. For pores larger than 1.5nm both models give the same results, at least at the adsorption pressure range studied here (1 – 700 bar). In particular, these observations do not depend on pressure.Both models shows that the H2 layer directly in contact with the pore wall is dense, with density largely exceeding the bulk density of liquid hydrogen at 33 K. This results confirm the recent experimental observations of hydrogen densification under confinement in carbon-based nanospaces [1, 2].

We have recently described how metastable aqueous dispersions of single layer graphene (SLG) can beprepared simply by transferring SLG, prepared by oxidation of fully exfoliated graphenide, into water, with nosurfactant.1 The aqueous graphene dispersions are named eau de Graphene (EdG) to convey the idea of waterwith only graphene inside.Here, we report the intrinsic Raman signatures of graphene dispersed in EdG and we show that theycorrespond to all the expected characteristics of SLG. We stress the difference in these signatures with respect tothose of the natural graphite precursor and to those of some aqueous dispersions of few-layers graphene (FLG)stabilized by surfactants. We discuss the Raman shifts of the G and 2D band in terms of doping and strain of thegraphene flakes2,3. Finally, by comparing the second order Raman signatures (D and D’ bands)3 of EdG and thoseof corresponding thin films, we discuss the nature and amount of defects on the graphene sheets.4,5 All togetherthis provides a full description of the structure and properties of graphene flakes dispersed in water without anyadditive.

The isotherms of molecular hydrogen adsorption in slit pores have been calculated at room temperature ( T = 298 K) for various pore sizes, from 0.6 nm to 2.5 nm. The pressure has been varied from 0 to 120 bar (12 MPa). The wall surface has been characterized by different values of the adsorption energy, from 3 to 25 kJ/mol. The provided raw data give the number of molecules adsorbed per nm 2 of the adsorbing wall, and can be used for fast storage capacity screening of new porous adsorbents with known

Les nanotubes de carbone monofeuillets (SWNT) présentent des propriétés physiques originales dues à leur composition –ils sont constitués uniquement d’atomes de carbone– et à leur faible dimensionnalité. En ce qui concerne leurs propriétés optiques, les SWNT semi-conducteurs émettent de la lumière dans le proche infrarouge –on parle de photoluminescence ou de fluorescence– à des longueurs d’onde qui dépendent de leur structure et de leur environnement diélectrique. Cet article traitera des phénomènes physiques à l’origine de la photoluminescence des SWNT, et en particulier leurs propriétés excitoniques, l’influence de la structure et de l’environnement sur le spectre de photoluminescence, ainsi que les perspectives d’applications en photonique.

The rise of efficient extraction techniques triggered a renewal of interest in semiconducting carbon nanotube (s-SWNT) research. It represents a great interest for optoelectronics, with outstanding properties in field-effect transistor, and s-SWNT ability to efficiently emit light in the near-IR range. In particular, the hybrid system polyfluorene (PFO) wrapped s‑SWNT (s-SWNT@PFO) display strong photoluminescence, and could be coupled with photonic devices such as microring resonators to control photoluminescence linewidth and enhance photoluminescence intensity.The main challenge for using s-SWNT@PFO in optoelectronics lies in the difficulty to establish good electrical contact with a PFO embedded carbon nanotube, and existing studies only focused on optical pumping of carbon nanotube networks, without addressing issues of electrical driving.We propose to investigate these issues using suspended s-SWNT@PFO networks. The network formation process allow to control nanotube density, while the amount of remaining metallic nanotube in the network could be adjusted at the extraction phase. A selective annealing process under low pressure is used to tune PFO wrapping around the nanotubes. The resulting s-SWNT@PFO networks are then probed by AFM, Raman spectroscopy, absorption, photoluminescence and electrical experiments.