Switchable surfactant-assisted carbon nanotube coatings: innovation through pH shift

The inner surface of fused-silica capillaries has been coated with a dense/homogeneous coating of commercial multi-wall carbon nanotubes (MWCNTs) using a stable ink as deposit precursor. Solubilization of the MWCNTs was achieved in water/ethanol/dimethylformamide by the action of a surfactant, which can switch between a neutral or an ionic form depending on the pH of the medium, which thus becomes the driving force for the entire deposition process. Careful control of the experimental conditions has allowed us to selectively deposit CNTs on the inner surface of insulating silica capillaries by a simple, reproducible, and easily adaptable method.The authors gratefully acknowledge the funding from the Ministerio de Economía y Competitividad, Generalitat Valenciana, and FEDER (Projects CTQ2012-31762, MAT2013-42007-P, PrometeoII/2014/10, JCI-2012-12664, and RyC 2009-03913)

Preparation of homogeneous CNT coatings in insulating capillary tubes by an innovative electrochemically-assisted method

Preparation of homogeneous CNT coatings in insulating silica capillary tubes is carried out by an innovative electrochemically-assisted method in which the driving force for the deposition is the change in pH inside the confined space between the inner electrode and the capillary walls. This method represents a great advancement in the development of CNT coatings following a simple, cost-effective methodology.Authors gratefully acknowledge the Explora program (MAT2011–13877–e) and funding from the Generalitat Valenciana, Ministerio de Economía y Competitividad and FEDER (Projects CTQ2012-31762, MAT2010-15273, PROMETEO /2009/047 and RyC 2009-03913)

Síntesis y caracterización de polianilinas auto-dopadas por copolimerización de Anilina y Ácido 2-aminobencenosulfónico: aplicaciones como biosensores y electrocatalizadores

El primer objetivo de este trabajo consiste en poner de relevancia como la sulfonación de la polianilina (PANI) tiene implicaciones profundas que afectan al material a todos los niveles, desde niveles microscópicos: mecanismos que rigen la oxidación/reducción, el dopado/desdopado del polímero; hasta un nivel macroscópico evaluando propiedades tales como la solubilidad y la conductividad eléctrica. Para ello se realizan estudios electroquímicos con el pH y la fuera iónica, sobre PANI sulfonada (SPAN) electro-generada, y seguidamente se emplean técnicas espectro-electroquímicas (UV-Vis-NIR, FTIR y EPR in situ). Posteriormente se estudia sobre la SPAN generada químicamente la influencia del grado de sulfonación en las propiedades macroscópicas más relevantes. En los siguientes capítulos se abordan investigaciones relacionadas con potenciales aplicaciones de la PANI auto-dopada. Los temas son dispares: i) la detección de indicadores fisiológicos en biomedicina y ii) la preparación de catalizadores para aplicaciones en reactores con fines energéticos. En ambos casos la aproximación es similar, el polímero presenta propiedades óptimas de conductividad y estabilidad para constituir una matriz donde inmovilizar un componente/fase catalíticamente activa y ejercer además como eficiente colector de corriente. En el presente trabajo de investigación se ahonda en dicha posibilidad desde una premisa clara, hallar unas condiciones de preparación que respeten al máximo la integridad del polímero

Friendly conditions-synthesis of platinum nanoparticles supported on conducting polymer: methanol electrooxidation

An easy method to synthesize Pt nanoparticles supported on conductive polymers has been explored. The synthesis was carried out under “soft” conditions, i.e., at low temperatures and without using strong reducing agent. The optimal synthesis conditions have been established. Thus, the particles had almost monodisperse size distribution, around 2.4 nm, when the synthesis was carried out at 100 °C, and around 1.4 nm when it was done at 75 °C. Also, it has been demonstrated that the platinum loading and the pretreatment of the catalyst determine the catalyst activity. Cyclic voltammetry in sulfuric acid displayed the processes of adsorption−desorption of hydrogen. The PANI−Pt catalysts have been checked in the oxidation of methanol, and a low degree of poisoning due to carbon monoxide adsorption has been detected in comparison with bulk platinum.Financial support by the Ministerio de Educación y Ciencia (Granrt MAT2004-1479) and the FEDER funds. H.J.S. thanks the Ministerio de Educación y Ciencia of Spain for a Juan de la Cierva Contract. C.S thanks the MEC for a FPU fellowship

Tuning the electroactivity of conductive polymer at physiological pH

This article studies the synthesis and properties of copolymers of aniline and both 2-amino (2ABSA) and 3-aminobenzenesulfonic acids (3ABSA)with a molar degree of sulfonation from 3 to 33% for 3ABSA and 10 to 43% for 2ABSA. The small segments of the sulfonic species in the polymer chain (molar fraction = 0.03) confer solubility in alkaline medium (around 0.012 g L−1) and good electrochemical response at pH 7.2 improving those for the unmodified polyaniline (PANI). Taking advantage of the electroactivity at physiological pH, the electrochemical response of redox couples (ferrocyanide(II)/ferricyanide(III) and ferrocene/ferrocenium) has been analysed. The electrochemical response of Cytochrome c (Cyt c)solutions has been also studied at pH 7.2 in presence and absence of ferrocene/ferrocenium species.Ministerio de Ciencia y Tecnología (MAT2004-1479)y programa Juan de la Cierva

Highly dispersed platinum nanoparticles on carbon nanocoils and their electrocatalytic performance for fuel cell reactions

Highly graphitic carbon nanocoils (GCNC) were synthesized through the catalytic graphitization of carbon microspheres obtained by the hydrothermal carbonization of different saccharides (sucrose, glucose and starch) andwere used as a support for Pt nanoparticles. The Pt nanoparticleswere deposited by means of a polymer mediated-polyolmethod. The Pt catalysts were characterized both physically (XRD, TEM, HRTEM and XPS) and electrochemically (electrooxidation of methanol in an acid medium). The electrocatalysts thus prepared show a high dispersion of Pt nanoparticles, with diameters in the 3.0–3.3nm range and a very narrow particle size distribution. These catalytic systems possess high electroactive Pt surface areas (up to 85m2 g−1 Pt) and they exhibit large catalytic activities towards methanol electrooxidation (up to 201Ag−1 Pt). Moreover, they have a high resistance against oxidation, which is considerably greater than that of the Pt/Vulcan system.Spanish MCyT (MAT2008-00407, MAT2007-60621 and FEDER)