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Modified metallic oxides for efficient photocatalysis

VLADIMIR ALONSO ESCOBAR BARRIOS DALIA VERONICA SANCHEZ RODRIGUEZ NANCY AYERIM CERVANTES RINCON ALMA BERENICE JASSO SALCEDO (2019)

"The aim of the chapter is to present modified materials like alternatives for conventional photocatalyst such as titanium dioxide. Discussion about silver/graphene nanoparticles-modified zinc oxide for the degradation of pollutants like triclosan or bisphenol A, both considered as endocrine disruptors, which affect the hormonal development of humans, is presented. The best conditions to obtain the highest photodegradation degree are established. In addition, the bismuth oxychloride has gained attention during the last 5 years for photocatalysis. In accordance, the obtained results for phenol photodegradation, using such oxychloride, are also presented. In the chapter, the characterization of photocatalyst is reported along with the proposal for mechanisms of action for the modified ZnO photocatalyst and the bismuth oxychloride."

Book part

ZnO Bismuth oxychloride Silver and graphene doped BIOLOGÍA Y QUÍMICA QUÍMICA QUÍMICA

Improved conductivity and anti(bio)fouling of cation exchange membranes by AgNPs-GO nanocomposites

MARIA IRENE LOPEZ CAZARES Fátima Pérez Rodríguez JOSE RENE RANGEL MENDEZ Marisol Centeno Sánchez Luis Felipe Cházaro Ruiz (2018)

"Nafion and Ultrex membranes were modified with nanocomposites (NCs) of silver nanoparticles (AgNPs) immobilized on graphene oxide (GO) as a thin film, using a polydopamine adhesive (pda). The morphological, physicochemical, transport, electrochemical and anti-(bio)fouling properties were determined. The results indicated that the silver nanoparticles were immobilized on adsorption points of the graphene oxide to form nanocomposites. Polydopamine acted satisfactorily as a support and adhesive to bind the nanocomposites to the outer and inner surface of the membranes. The hydrophilicity, ionic exchange capacity, fixed ion concentration, electrochemical and conductivity properties were mostly enhanced in the modified Nafion membranes with pdaGO and pdaNC, but in the Ultrex a shortening of the hydrophilic channels occurred. The impedance results suggested that both modified membranes were more conductive at low frequencies or longer times, due to an adequate interfacial distribution of charges. The differences were attributed to the microstructure of the membranes. Also, the modification of Nafion and Ultrex membranes improved their anti-(bio)fouling properties. Hence, both membranes could be used in separation systems, since they allow a higher charge transfer and low energy consumption."

Article

Modified cationic exchange membranes Silver nanoparticles-graphene oxide nanocomposites Proton conductivity Anti-(bio) fouling properties Electrical conductivity CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA FÍSICA MOLECULAR POLÍMEROS POLÍMEROS

electroactivity of few-layered graphene/polyaniline composites

ERASTO ARMANDO ZARAGOZA CONTRERAS ALEJANDRO VEGA RIOS CLAUDIA ALEJANDRA HERNANDEZ ESCOBAR FLOR YANHIRA RENTERIA BALTIERREZ (2012)

In this study, we used the dual functionality of anilinium dodecyl sulfate (DS-AN) both to exfoliate expanded graphite (EG) and to produce grapehene/polyaniline composites, in a two-step method. On the one hand, DS-AN performs the common functions of a surfactant, and on the other hand, the salt is a monomer to propagate polyaniline, that is, DS-AN is a reactive surfactant (or surfmer).

Conference proceedings

Graphene BIOLOGÍA Y QUÍMICA QUÍMICA QUÍMICA FÍSICA OTRAS

Gold, Silver, and Copper phytoextraction by helianthus annuus sunflower grown on mine tailings amended with plant growth regulators and cyanide

Werner Rubio Carrasco Jeiry Toribio Jiménez (2014)

In 1998, it was reported that plants of Brassica juncea (L) Czern. Could be forced to accumulate Au to concentrations as high as 57 mg/kg of dry matter after suitable treatment of the substrate in which they were growing

Phytoextraction has been suggested as aviable technique for gold recovery from some areas of mine tailings and mineralized soils. Plant Growht Regulators have been used due to their potential to improve rates of metal phytoextraction.

Article

Rooting Phytoextraction Mine tailings Helianthus annuus gold Copper Silver BIOLOGÍA Y QUÍMICA QUÍMICA

Synthesis of carbon nano-onions doped with nitrogen using spray pyrolisis

EDUARDO TOVAR MARTINEZ JOSE ADAN MORENO TORRES JORGE VALENTIN CABRERA SALAZAR MARISOL REYES REYES Luis Felipe Cházaro Ruiz ROMAN LOPEZ SANDOVAL (2018)

"In this work, we have synthesized carbon nano-onions (CNOs) doped with nitrogen and iron carbide core. These nanostructures were synthesized pyrolysing various alcohol-benzylamine reaction mixtures. These CNOs showed a certain degree of functionalization of their surfaces, depending of the solvent, as well as n-type doping due to the inclusion of N atoms in the graphene layers. Ratios of O atoms to C atoms as well as to N atoms of the pyrolyzed solution play an important role in the morphology of the CNOs and on the phase of the iron core. Differences in the morphology of the samples have an important effect on their electrical conductivity as well as in their electrochemical properties. Synthesized samples showing well-defined CNOs, the sintering between them is negligible, have a low conductivity and higher capacitance, while those samples showing the best conductivities and lower capacitances, the CNOs in samples are connected between them by turbostratic graphite ribbons, in similar way to the CNOs synthesized from carbon nanodiamond annealed in argon atmosphere."

Article

Electrochemical performance Raman-spectroscopy Oxygen Nanotubes Reduction Nanodiamond Nanoparticles Graphene Soot Microscopy BIOLOGÍA Y QUÍMICA QUÍMICA QUÍMICA

Study of the optical properties of dielectric-graphene-dielectric multilayer quasi-periodic structures: Thue-Morse case

IRERI AYDEE SUSTAITA TORRES ISAAC RODRIGUEZ VARGAS JESUS MADRIGAL MELCHOR (2017)

Potential applications in optoelectronics had generated a great interest on the study of graphene optical properties. Along with this, graphene has exceptional properties such as high mobility and optical transparency, flexibility, mechanical robustness, etc. Due to these properties, graphene could be used in different devices such as transparent conductors, organic light-emitting diodes, photodetectors, touch screens, saturable absorbers and ultrafast lasers. A transfer-matrix method is used in order to calculate graphene optical properties, such as transmission, and absorption in the infrared region. The quasi-periodic structure consists in intercalated graphene sheets between two consecutives dielectrics. The dielectric materials follow the Thue-Morse sequence (ThMo). The graphene sheets are described by the optical conductivity considering interband and intraband transitions. The structure of the spectra depends strongly on the number of sequence generation, width of the different dielectrics and dielectric permittivity. In our case, the infrared region corresponds to a chemical potential greater than kT. In the calculated spectra, the geometrical properties of the Thue-Morse sequence can be observed. We obtain absorption bands well defined.

En este estudio se usó el método de Matriz de Transferencia para calcular las propiedades ópticas de Transformación y Absorción en la región infrarroja. La estructura estudiada consiste en un arreglo cuasi-periódico intercalando láminas de grafeno entre dos dieléctricos consecutivos. Los materiales dieléctricos siguen una secuencia Thue-Morse (ThMo). Las láminas de grafeno son descritas por medio de su conductividad óptica considerando las transiciones interbanda e intrabanda. La estructura de los espectros depende fuertemente del número de generación, espesor de los diferentes dieléctricos y de la permitividad de los dieléctricos. En nuestro caso, en la región infrarroja corresponde a una región donde el potencial químico del grafeno es mucho mayor que kT. En los espectros obtenidos, las propiedades geométricas de la secuencia Thue-Morse puede ser observada. Nosotros obtenemos bandas de absorción bien definidas.

Producción Científica de la Universidad Autónoma de Zacatecas UAZ

Article

INGENIERÍA Y TECNOLOGÍA Multilayer system Graphene Quasi-regular Thue-Morse

Optical Properties of Dielectric-Graphene Left Hand Material Structure

JESUS MADRIGAL MELCHOR (2019)

It is well known the remarkable optical properties of both graphene and left handed materials,

for which we study the optical properties of a multilayer system building by graphene-

dielectric-left hand material. In this work, we show the transmission, reflection and

absorption spectra for a different set of parameters of the left-handed material structure. It is

important to highlight that the inclusion of graphene remarkably modifies the transmission

and absorption spectra. The optical properties of the graphene-LHM can be modulated via

the different parameters of system. We showed that the fill function do not change the line

form of the spectra, however, modify their amplitudes. With respect to light polarization, it's

possible to observe that the spectra are widen for TM respect to TE polarization.

Son bien conocidas las extraordinarias propiedades ópticas tanto del grafeno como de los metamateriales izquierdos (LHM), para los cuales estudiamos sus propiedades ópticas en sistemas multicapas fabricados por grafeno-metamateriales izquierdos. En este trabajo, mostramos los espectros de transmisión, reflexión y absorción para diferentes conjuntos de parámetros de la estructura del metamaterial izquierdo. Es importante resaltar que la inclusión del grafeno modifica considerablemente los espectros de transmisión y absorción. Las propiedades ópticas del sistema grafeno-LHM puede ser moduladas vía los diferentes parámetros del sistema. Mostramos que la función de llenado no camba la forma de línea de los espectros, sin embargo, modifica sus amplitudes. Con respecto a la polarización d ella luz, es posible observar son más anchos para polarización TM que con respecto a luz con polarización TE.

Producción Científica de la Universidad Autónoma de Zacatecas UAZ

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA Left-Hand Materials Graphene Multilayers

Trends in nanoscience, nanotechnology, and carbon nanotubes: a bibliometric approach

Emilio Muñoz Sandoval (2014)

"Carbon nanotubes are currently one of the most important materials due to their strong mechanical resistance, light weight, and transport properties. Since the publication of Ijima’s paper on tubular carbon structures (Iijima, Nature 354:56–58, 1991), approximately 80,000 research articles have been published according to the ISI web of science (WOS) database, using “carbon nanotube*” as the search criterion in the search by topic option. In this work, the development and impact of nanoscience and nanotechnology (N&N) and carbon nanotubes on several research areas, journals, specific papers, and emerging research areas are analyzed and discussed. Considering the production of papers in these areas from 1997 to 2012, quantitatively speaking, the People’s Republic of China is emerging as the leading country in N&N and carbon nanotube research, passing the United States of America. WOS data analysis of nanoscience, nanotechnology, and carbon nanotube research in developed and developing countries is discussed, and some ideas for accelerating the progress in these important research areas are proposed."

Article

Carbon nanotubes Graphene Nanotechnology Nanoscience BIOLOGÍA Y QUÍMICA QUÍMICA QUÍMICA

Angle-dependent bandgap engineering in gated graphene superlattices

ISAAC RODRIGUEZ VARGAS (2016)

Graphene Superlattices (GSs) have attracted a lot of attention due to its peculiar

properties as well as its possible technological implications. Among these characteristics

we can mention: the extra Dirac points in the dispersion relation and the

highly anisotropic propagation of the charge carriers. However, despite the intense

research that is carried out in GSs, so far there is no report about the angular

dependence of the Transmission Gap (TG) in GSs. Here, we report the dependence

of TG as a function of the angle of the incident Dirac electrons in a rather

simple Electrostatic GS (EGS). Our results show that the angular dependence of

the TG is intricate, since for moderated angles the dependence is parabolic, while

for large angles an exponential dependence is registered. We also find that the

TG can be modulated from meV to eV, by changing the structural parameters of

the GS. These characteristics open the possibility for an angle-dependent bandgap

engineering in graphene

Producción Científica de la Universidad Autónoma de Zacatecas UAZ

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA band structure engineering Bandgap engineering graphene

Gold, silver, and copper phytoextraction by helianthus annuus l. (sunflower) grown on mine tailings amended with plant growth regulators and cyanide

Leopoldo Partida Ruvalcaba Werner Rubio Carrasco Jeiry Toribio Jiménez (2014)

Phytoextraction has been suggested as aviable technique for gold recovery from some areas of mine tailings and mineralized soils. Plant Growth Regulators have been used due to their potential to improve rates of metal phytoextraction. However, no studies have specifically described the efficacy of exogenous plant growth regulators on the process of gold phytoextraction for plants grown in mine tailings.

Article

Rooting Phytoextraction Mine tailings Helianthus annuus L Gold Copper Silver CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO