Modulation of the exfoliated graphene work function through cycloaddition of nitrile imines

After the feasibility of the 1,3-dipolar cycloaddition reaction between nitrile imines and exfoliated graphene by density functional theory calculations was proved, very few-layer graphene was effectively functionalized using this procedure. Hydrazones with different electronic properties were used as precursors for the 1,3-dipoles, and microwave irradiation as an energy source enabled the reaction to be performed in a few minutes. The anchoring of organic addends on the graphene surface was confirmed by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis. Ultraviolet photoelectron spectroscopy (UPS) was used to measure the work function and band gap of these new hybrids. Our results demonstrate that it is possible to modulate these important electronic valence band parameters by tailoring the electron richness of the organic addends and/or the degree of functionalization

Challenge B: Human sciences in transition scenarios

Coordinators: Josep Martí Pérez (IMF, CSIC), Idoia Murga Castro (IH, CSIC).This challenge is formulated in terms of “humanities in transition,” that is, their approach and articulation in the face of the changes they must undergo to achieve the social weight that, due to their intrinsic relevance, should correspond to them. Faced with these situations that would demand a reinforcement in research and dissemination in diverse aspects of the humanities, from multiple perspectives, paradoxically an adverse panorama is drawn for the development and dissemination of humanistic knowledge, which concerns different factors. Some are related to the consideration of the area of knowledge itself, its organization within the scientific system, the questioning of its own limits, and the interaction with another knowledge. Considering current transition scenarios does not mean having to abandon old objectives, but it adds to the work conducted new objects of study closely related to current reality, such as: the informational revolution; the relations with the ecosystem and the environmental crisis; globalization; the intensification of human mobility and migration flows; the growing economic and social inequality; the frictions derived from the articulation of collective identities; the decolonization of discourses; demographic dynamics; integration of technological advances; and viability and support for alternative models of society.Peer reviewe

Photochemical Evidence of Electronic Interwall Communication in Double-Wall Carbon Nanotubes

Single- and double-wall carbon nanotubes (CNTs) having dimethylanilino (DMA) units covalently attached to the external graphene wall have been prepared by the reaction of the dimethylaminophenylnitronium ion with the corresponding CNT. The samples have been characterized by Raman and XPS spectroscopies, thermogravimetry, and high-resolution transmission electron microscopy in which the integrity of the single or double wall of the CNT and the percentage of substitution (one dimethylanilino group every 45 carbons of the wall for the single- and double-wall samples) has been determined. Nanosecond laser flash photolysis has shown the generation of transients that has been derived from the charge transfer between the dimethylanilino (as the electron donor) to the CNT graphene wall (as the electron acceptor). Importantly, the lifetime of the double-wall CNT is much shorter than that monitored for the single-wall CNT. Shorter-lived transients were also observed for the pentyl-esterified functionalized double-wall CNT with respect to the single-wall analogue in the presence of hole (CH3OH) and electron quenchers (O2, N2O), which has led to the conclusion that the inner, intact graphene wall that is present in double-wall CNT increases the charge mobility significantly, favoring charge recombination processes. Considering the importance that charge mobility has in microelectronics, our finding suggests that double-wall CNT or two-layer graphene may be more appropriate to develop devices needing fast charge mobility.Financial support from the Ministry of Science and Innovation of Spain, (CTQ2010-17498, PLE2009-0038 and Consolider-Ingenio Projects HOPE CSD2007-00007 and MULTICAT) is gratefully acknowledged. P. A. also thanks the Spanish Ministry of Science and Innovation for a Juan de la Cierva research associate contract. We thank to Maria Jose de la Mata for the TGA experiments.Vizuete, M.; Gómez-Escalonilla, MJ.; García-Rodríguez, S.; García Fierro, JL.; Atienzar Corvillo, PE.; García Gómez, H.; Langa, F. (2012). Photochemical Evidence of Electronic Interwall Communication in Double-Wall Carbon Nanotubes. Chemistry - A European Journal. 18(52):16922-16930. doi:10.1002/chem.201202000S1692216930185

Photoinduced electron transfer in a carbon nanohorn-C60 conjugate

A nanohybrid combining two allotropic forms of carbon, namely carbon nanohorns (CNH) and C60, has been obtained from a C60 derivative bearing a benzocrown ether subunit (crown–C60) and a CNH functionalized with NH3+ groups (CNH-sp-NH3+F−) through ammonium–crown ether interactions. The resulting CNH–C60 nanohybrid has been characterized by Raman and XPS spectroscopies, thermogravimetric analysis (TGA) and high-resolution transmission electron microscopy (HR-TEM). The photophysical properties of the CNH–C60 conjugate have been investigated in benzonitrile. Femtosecond laser flash photolysis measurements revealed the occurrence of an efficient electron transfer from the singlet excited state of the C60 moiety to the CNH with a rate constant of 6.5 × 1010 s−1 to produce a radical ion pair, which decayed by charge recombination with a lifetime of 1.0 ns to afford the triplet excited state of CNH-sp-NH3+F− and crown–C60. The two carbon nanoforms play therefore complementary roles in the CNH–C60 conjugate, the CNH acting as an electron donor and C60 as an electron acceptor.The research at Osaka University was supported by Grant-in-Aid (no. 20108010 to SF and no. 23750014 to KO) and Global COE program, “the Global education and Research Centre for Bio-Environmental Chemistry” from the Ministry of Education, Culture, Sports, Science and Technology, Japan and by WCU (R31-2008-000-10010-0) and GRL (2010-00353) programs of KOSEF/MEST, Korea. The research at University of Castilla-La Mancha was supported by the Ministry of Economy and Competitiveness of Spain (projects CTQ2010–17498/BQU and PLE-2009-0038).Peer Reviewe

Modulation of the exfoliated graphene work function through cycloaddition of nitrile imines

After the feasibility of the 1,3-dipolar cycloaddition reaction between nitrile imines and exfoliated graphene by density functional theory calculations was proved, very few-layer graphene was effectively functionalized using this procedure. Hydrazones with different electronic properties were used as precursors for the 1,3-dipoles, and microwave irradiation as an energy source enabled the reaction to be performed in a few minutes. The anchoring of organic addends on the graphene surface was confirmed by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis. Ultraviolet photoelectron spectroscopy (UPS) was used to measure the work function and band gap of these new hybrids. Our results demonstrate that it is possible to modulate these important electronic valence band parameters by tailoring the electron richness of the organic addends and/or the degree of functionalization