Suchergebnisse

The MoS2 nanocrystals coupled with anatase nanoparticles were prepared by the solvothermal method at relatively low temperatures. It was determined that the materials consisted of 15–20 nm diameter anatase nanoparticles with highly dispersed MoS2 nanocrystals of approximately 3–7 nm in size. Visible light absorption in the MoS2–TiO2 samples increased with the MoS2 content. However, their lambda edges (λedge) remained almost identical at approximately 390 nm, meaning that MoS2 did not cause a red shift in the anatase bandgap energy. The hybrid MoS2-anatase materials had higher surface area (70–124 m2 g−1) than commercial TiO2 (P25) (50 m2 g−1). The MoS2-anatase hybrid nanocrystals showed enhanced activity in the oxidation of methylene blue in water under UV light irradiation. A photomechanism able to elucidate the observed dye decolourisation was suggested. ; This work was funded by the Government of Aragon and 'La Caixa' Ref. GA-LC-041/2008 and by the Spanish Ministry of Science and Innovation Ref. EUI2008-00152. ; Peer reviewed

Resumen del trabajo presentado al Internantional Meeting on the Chemistry of Nanotubes: Science and Applications (ChemonTubes), celebrado en Zaragoza del 6 al 9 de abril de 2008. ; Funding from Spanish Ministry of Education and Science (MEC) and European Regional Development Fund (ERDF) under projects NANOPOLICOND (MAT 2006-13167-C02-02) and NANO-TPE (MAT2007-66927- C02-01), as well as from Regional Government of Aragon (DGA) under Consolidated Group Programme (DGAT66 CNN) is gratefully acknowledged. ; Peer reviewed

14 pages,8 figures, 6 tables; available on line 5 September 2013 ; Arc discharge single-walled carbon nanotubes (SWCNTs) were modified through different oxidative treatments and functionalization reactions. The modified SWCNT powders were dispersed in four different aqueous media and purified by ultracentrifugation. Extinction coefficients of the modified SWCNTs depended on the SWCNT type but did not depend on the dispersion medium. According to visible/near infrared spectroscopy, the purity of all the modified SWCNT dispersions substantially improved after ultracentrifugation; however, the spectrum profile, the degree of purity and the centrifugation yield were influenced by the SWCNT type, the surface functional groups and the dispersion medium. Semi-quantitative purity indexes calculated from optical absorption spectra were supported by transmission electron microscopy observations. Contents in metal impurities were analyzed by energy dispersive X-ray spectroscopy. SWCNT samples processed by oxidative acid treatments and ultracentrifugation showed metal contents of lower than 0.5 wt%. ; This work was funded by the Spanish MINECO under the projects TEC2010-15736 and PRI-PIBAR-2011-1, and the Government of Aragon (DGA) and the European Social Fund (ESF) under Project DGA-ESF-T66 CNN. ; Peer Reviewed

Resumen del trabajo presentado al ChemOnTubes, celebrado en Bruselas (Bélgica) del 3 al 7 de abril de 2016. ; This work has been funded by MINECO and European Regional Development Fund (ENE2013-48816-C5-5-R NANOSOL-MAT), CSIC (project 2015801011 Intramural), Government of Aragón and European Social Fund (DGA-ESF-T66 Grupo Consolidado) and European Commission (H2020-MSCA-ITN-2014-ETN 642742 Enabling Excellence). ; Peer reviewed

Resumen del trabajo presentado al HeteroNanoCarb: "Advances and Applications in Carbon Related Nanomaterials: From pure to doped structures including heteroatom layers", celebrado en Benasque (España) del 7 al 11 de diciembre de 2015. ; This work has been funded by the Spanish Ministry MINECO and the European Regional Development Fund under the project ENE2013-48816-C5-5-R, and the Government of Aragon and the European Social Fund (DGA-ESF-T66 Grupo Consolidado). ; Peer reviewed

© 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ ; Polyvinylidene fluoride (PVDF)/single-walled carbon nanotube (SWCNT) composites are characterized by X-ray diffraction and scanning calorimetry, and studied by dielectric relaxation spectroscopy (DRS) in the temperature range of −75 to 150 °C. The effects of SWCNTs and SWCNT functionalization are analyzed in terms of α and αc relaxation, dielectric permittivity, loss tangent, and AC electrical conductivity. Some small changes are detected in α relaxation with the addition of SWCNTs, and a strong influence of SWCNTs is observed in the other relaxation αc. Below the percolation threshold, the dielectric permittivity of functionalized SWCNT composites increases compared to blank PVDF, without notable changes in the dielectric loss. All the composite systems show an electrical percolation behavior with different thresholds depending on SWCNT functionalization. Threshold concentrations remain nearly unchanged in the whole temperature and frequency ranges. The base PVDF conductivity strongly depends on temperature and frequency, while the maximum conductivity above the percolation remains nearly unchanged (∼10−2 S/m) for all the systems, temperatures and frequencies. ; Special thanks are directed to the Analysis Service of Instituto de Carboquímica, ICB-CSIC, in particular to I. Fernández. This work has been funded by MINECO and European Regional Development Fund (ENE-2016-79282-C5-1-R), and Government of Aragon and European Social Fund (DGA-T50 and DGA-ESF-T66 "Grupos Consolidados"). ; Peer reviewed

The unzipping of temperature-induced multi-walled carbon nanotubes (MWCNTs) to yield graphene nanoribbons (GNRs) has been studied. These carbon nanomaterials consisting of MWCNTs and unzipped MWCNTs have been synthesized, thoroughly characterized, and subsequently evaluated for electrochemical sensing. Three temperatures (55, 65 and 75 ºC) yielding three carbon nanomaterial termed as GNR-55, GNR-65 and GNR-75, respectively, were carefully studied. Interestingly, GNR-65 became the most suitable material for the electrochemical sensing of a wide range of model analytes displaying the best electrochemical response with independence of the analysed molecule. This electrochemical behaviour seems to be associated to the progress of the unzipping reaction that influences the balance between the Csp2/Csp3 ratio, the graphitic fraction and the type of functional groups introduced. These results revealed the importance of the temperature in the synthesis process, for tailoring carbon nanomaterials which could be used in a particular molecular detection application opening new opportunities for electrochemical sensing applications. ; This work has been Financial supported by the Spanish Ministry of Science and Innovation (CTQ2011-28135), the NANOAVANSENS program from the Community of Madrid (S2013/MIT-3029), the Spanish MINECO (ENE2013-48816-C5-5-R), the Government Aragon (Project DGA_ESF-T66 CNN) and the European Social Fund (ESF). D. A. M. acknowledges the FPU fellowship from the Ministry of Education, Culture and Sports. D. M. M.-G. acknowledges the fellowship received from the NANOAVANSENS program. ; Peer reviewed

Hybrid film electrodes were made of nanocrystalline titanium dioxide (TiO2) and various percentages of single‐walled carbon nanotube (SWCNT) fillers up to 5.5 wt%. A complete photoelectrochemical study was performed in both alkaline and acidic conditions by using cyclic voltammetry, potentiostatic photocurrent measurements, and open‐circuit‐potential measurements under UV/Vis irradiation. Dark voltammograms show a transition from a capacitive to a resistive behavior in the TiO2 accumulation region upon increasing SWCNT percentages. In addition, the energy levels of deep electron traps change inside the TiO2 bandgap. The new peak positions correspond to the reduction potentials of SWCNTs, and their associated charge capacities increase with the SWCNT percentage. The modifications observed in dark experiments directly impact on the shape profile of cyclic voltammograms under irradiation. As a consequence, reduction potentials of SWCNTs appear near the cathodic peaks of certain water oxidation intermediates, and may be interacting with them. On the other hand, open‐circuit photopotentials reach maximum values for small SWCNTs percentages around 0.02 wt%. An increase in potentiodynamic and potentiostatic photocurrents is observed for the electrode containing 0.02 wt% SWCNTs, compared to reference TiO2 in acidic conditions. ; The authors thank the Institute for Biocomputation and Physics of Complex Systems (BIFI) for the centrifugation laboratory. This work has been funded by MINECO and European Regional Development Fund (ENE 2016-79282-C5-1-R), Government of Aragon and European Social Fund (DGA-ESF-T66 "Grupo Consolidado") and European Commission (H2020-MSCA-ITN-2014-ETN 642742 "Enabling Excellence"). ; Peer reviewed

7 Figuras.- 3 Tablas ; This work is focused on the development of an electrochemical sensor for the quantification of Cd(II) based on the use of glassy carbon electrodes (GCE) modified with a dispersion of single-walled carbon nanotubes (SWCNTs) covalently functionalized with cysteine (Cys). Cd(II) is preconcentrated at the electrode surface by complex formation at open circuit potential, followed by the reduction at ∧0.900 V and the final anodic voltammetric stripping in a 0.020 M acetate buffer solution pH 5.00. The functionalization of SWCNTs was performed through the reaction between the carboxylic groups of oxidized SWCNT and amino groups of S-triphenylmethyl cysteine using a coupling chemistry agent based on benzotriazol for the activation of carboxylic residues. There was a linear relationship between Cd oxidation signal and Cd(II) concentration between 1.0 and 300.0 α/4gL∧1 Cd(II), with a sensitivity of (49 ± 2) í 10∧3 α/4Aα/4g∧1L and a detection limit of 0.3 α/4gL∧1. The reproducibility was 1.7% using the same dispersion and 3.8% using 3 different dispersions. The sensor was challenged with groundwater samples enriched with Cd(II) showing excellent recovery percentages and excellent agreement with the values obtained by ICP-MS. ; The authors thank CONICET, SECyT-UNC, ANPCyT, MINCyT-Córdoba, Spanish Ministry of Economy and Competitiveness (MINECO) project ENE2013-48816-C5-5-R, and the Government of Aragon and the European Social Fund under project grant DGA-FSE-T66 CNN for the financial support. ; Peer reviewed

Resumen del trabajo presentado al Nanomath, celebrado en Toulouse (Francia) del 27 al 30 de junio de 2016. ; This work has been funcled by MINECO ancl Europea.n Regional Development Funcl (ENE2013-48816-C5-5-R "NANOSOL-MAT"), CSIC (project 2015801011 "Int.ramural"), Government of Aragón and European Social Fund (DGA-ESF-T66 "Grupo Consolidado") ancl European Commission (H2020-MSCA-ITN-2014-ETN 642742 "Enabling Excellcnce"). ; Peer reviewed

Poly(methyl methacrylate) (PMMA) composites containing raw or purified single-walled carbon nanotubes (SWCNTs) are prepared by in-situ polymerization and solution processing. The SWCNTs are purified by centrifugation in a Pluronic surfactant, which consists of polyethyleneoxide and polypropyleneoxide blocks. Both the effects of SWCNT purity and non-covalent functionalization with Pluronic are evaluated. Electrical conductivity of PMMA increases by 7 orders of magnitude upon the integration of raw or purified SWCNTs. The best electrical properties are measured for composites made of purified SWCNTs and prepared by in-situ polymerization. Strains at fracture of the SWCNT/PMMA composites are nearly identical to those of the neat matrix. A certain decrease in the work to fracture is measured, particularly for composites containing purified SWCNTs (-31.6 %). Fractography and Raman maps indicate that SWCNT dispersion in the PMMA matrix improves upon the direct addition of Pluronic, while dispersion becomes more difficult in the case of purified SWCNTs. ; This work was funded by the Spanish MINECO under the projects TEC2010-15736, MAT2010-16175 (CICYT), CTQ2006-02330 and PRI-PIBAR-2011-1, and the Government of Aragon (DGA) and the European Social Fund (ESF) under Project DGA-ESF-T66 CNN. C. Ruano acknowledges MINECO for her PhD grant BES2007-17250. ; Peer reviewed

9 pages, 9 figures.-- Available online 21 February 2014 ; The effect of -irradiation on the structure and composition of chemically synthesized few-layered graphene materials was studied. Fully oxidized graphene oxide and graphene nanoribbons, as well as their respective chemically post-reduced forms, were treated under -irradiation in an air-sealed environment. Three different irradiation doses of 60, 90 and 150 kGy were applied. Structure and composition of the irradiated materials were analyzed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), Raman spectroscopy and Xray photoelectron spectroscopy (XPS). The XRD patterns were not affected by - irradiation, and small changes were observed in the FTIR and TGA results. However, significant modifications were detected by Raman spectroscopy and XPS, particularly in the Raman G/D band intensity ratios and in the C 1s XPS profiles. Comparatively, the changes in Raman and XPS spectra after -irradiation were even greater than those occurring during the chemical reduction of graphene oxides. Our results indicate that the graphene carbon lattice was strongly affected by -irradiation, but the materials experienced small variations in their oxygen content. ; This work was funded by the Spanish MINECO under the projects TEC2010-15736, MAT2010-15026, MAT2010-16175 (CICYT) and PRI-PIBAR-2011-1, CSIC under Project 201080E124 and the Government of Aragon (DGA) and the European Social Fund (ESF) under Project DGA-ESF-T66 CNN. ; Peer reviewed