Research Center en Materiales

Chih, Mexico

Research Center en Materiales

Chih, Mexico
Time filter
Source Type

Gomez-Monsivais A.C.,CIDETEQ | Gomez-Monsivais A.C.,Tijuana Institute of Technology | Velazquez-Hernandez I.,CIDETEQ | Alvarez-Contreras L.,Research Center en Materiales | And 4 more authors.
Energies | Year: 2017

Currently, the ethanol electro-oxidation reaction has attracted considerable attention in fuel cells because of new green ethanol synthetic methods based on biomass processes that have emerged. In this study, PtFe/C and Pt/C nanoparticles were synthesized by a chemical reduction method and tested in the ethanol electro-oxidation reaction. Furthermore, the electrocatalytic effect of the PtFe bimetallic catalyst was analyzed by in situ surface-enhanced Raman spectroscopy (SERS) coupled to an electrochemical cell. X-ray diffractograms showed typical face-centered cubic structures with crystallite sizes of 3.31 and 3.94 for Pt/C and PtFe/C, respectively. TEM micrographs revealed nanoparticle sizes of 2 ± 0.4 nm and 3 ± 0.6 nm for Pt/C and PtFe/C respectively. PtFe/C exhibited a Pt90Fe10 composition by both X-ray fluorescence and energy-dispersive X-ray spectroscopy. A better electrocatalytic activity as function of concentration was obtained through the incorporation of a small amount of Fe into the Pt lattice and the presence of Fe2+/Fe3+ (observed by X-ray photoelectron spectroscopy). According to SERS experiments, the presence of these iron species promotes the chemisorption of ethanol, the formation of formic acid as main product and renewal of the catalytic sites, resulting in current densities that were at least three fold higher than the values obtained for the Pt/C nanocatalyst. © 2017 by the authors. Licensee MDPI.

Hernandez-Gordillo A.,San Luis Potosí Institute of Scientific Research and Technology | Hernandez-Gordillo A.,National Autonomous University of Mexico | Obregon S.,University of Seville | Paraguay-Delgado F.,Research Center en Materiales | Rodriguez-Gonzalez V.,San Luis Potosí Institute of Scientific Research and Technology
RSC Advances | Year: 2015

Unprecedented photoactivity of silver nanoparticles photodeposited on nanocrystalline TiO2 for the efficient reduction of 4-nitrophenol at room temperature is reported. The use of Na2SO3 as a harmless scavenger agent for the reduction of a nitroaromatic endocrine disruptor yields a valuable 4-aminophenol reagent. © 2015 The Royal Society of Chemistry.

Alvarez-Herrera C.,Autonomous University of Chihuahua | Murillo-Ramirez J.G.,Research Center en Materiales | Perez-Reyes I.,Autonomous University of Chihuahua
Journal of Optics (United Kingdom) | Year: 2015

This work reports the thermal convection with imposed shear flow in a thin two-plate channel. Flow structures are investigated under heating asymmetric conditions and different laminar flow conditions. The dynamics of heat flow and the energy distribution were determined by visualization with the Schlieren technique and application of the proper orthogonal decomposition (POD) method. The obtained results from the POD mode analysis revealed that for some flow conditions the heat transfer is related to the energy of the POD modes and their characteristic numbers. It was possible to detect periodic motion in the two-plate channel flow from the POD mode analysis. It was also found that when the energy is distributed among many POD modes, the fluid flow is disorganized and unsteady. © 2015 IOP Publishing Ltd.

Martinez-Lopez A.L.,Laboratory of Biopolymers | Carvajal-Millan E.,Laboratory of Biopolymers | Miki-Yoshida M.,Research Center en Materiales | Alvarez-Contreras L.,Research Center en Materiales | And 3 more authors.
Molecules | Year: 2013

The aim of this research was to study the structural and textural characteristics of maize bran arabinoxylan (MBAX) microspheres. The laccase-induced cross-linking process was monitored by storage (G') and loss (G'') moduli changes in a 4% (w/v) MBAX solution. The G' and G'' values at the plateau region were 215 and 4 Pa, respectively. After gelation, the content of ferulic acid dimers decreased from 0.135 to 0.03 μg/mg MBAX, suggesting the formation of ferulated structures unreleased by mild alkaline hydrolysis. MBAX microspheres presented an average diameter of 531 μm and a swelling ratio value (q) of 18 g water/g MBAX. The structural parameters of MBAX microspheres were calculated from equilibrium swelling experiments, presenting an average mesh size of 52 nm. Microstructure and textural properties of dried MBAX microspheres were studied by scanning electron microscopy and nitrogen adsorption/desorption isotherms, respectively, showing a heterogeneous mesoporous and macroporous structure throughout the network. © 2013 by the authors.

Maya-Cornejo J.,CIDETEQ | Ortiz-Ortega E.,Autonomous University of Queretaro | Alvarez-Contreras L.,Research Center en Materiales | Arjona N.,CIDETEQ | And 3 more authors.
Chemical Communications | Year: 2015

A membraneless nanofluidic fuel cell with flow-through electrodes that works with several fuels (individually or mixed): methanol, ethanol, glycerol and ethylene-glycol in alkaline media is presented. For this application, an efficient Cu@Pd electrocatalyst was synthesized and tested, resulting outstanding performance until now reported, opening the possibility of power nano-devices for multi-uses purposes, regardless of fuel re-charge employed. This journal is © The Royal Society of Chemistry 2015.

Martinez-Flores J.J.,Research Center en Materiales | Licea-Jimenez L.,Research Center en Materiales | Perez Garcia S.A.,Research Center en Materiales | Rodriguez-Viejo J.,Autonomous University of Barcelona | Alvarez-Quintana J.,Research Center en Materiales
Journal of Applied Physics | Year: 2012

Thermal impedance Zth(iω) is a way of defining the thermophysical characteristics and behavior of thermal systems. Existing photoacoustic and photothermal approaches based on thermal impedance formalism merely allows a partial thermal characterization of the materials (generally, either thermal diffusivity or thermal effusivity). In this work, a new approach based on the thermal impedance concept in terms of its characteristic thermal time constant is developed from thermal quadrupoles formalism. The approach outlined in this contribution presents a set of analytical equations in which through a single measurement of thermal impedance is sufficient to obtain a comprehensive characterization of the thermophysical properties of solid materials in a simple way. © 2012 American Institute of Physics.

Carrillo-Vazquez V.M.,Research Center en Materiales | Murillo J.G.,Research Center en Materiales
Journal of Physics: Conference Series | Year: 2015

The optical characterization of the Si-ZnO hybrid photonic device fabricated and studied in this work revealed its ability to selectively enhance the reflectance on specific wavelengths in the border of VIS-NIR range. This ability was attributed to the coupling of the embedded micro-cavities in the photonic crystal. The results found suggest the presence of a photonic band gap around the border of VIS-NIR range in the hybrid photonic structure studied. © Published under licence by IOP Publishing Ltd.

Arizmendi-Morquecho A.,Research Center en Materiales | Chavez-Valdez A.,Friedrich - Alexander - University, Erlangen - Nuremberg | Alvarez-Quintana J.,Research Center en Materiales
Applied Thermal Engineering | Year: 2012

The high temperature behavior of electrophoretically deposited thermal barrier coatings based on recycled fly ash cenospheres is presented. Thermal properties such as thermal expansion coefficient, specific heat, thermal conductivity, thermal diffusivity and thermal effusivity of fly ash (FA) and fly-ash cenospheres (FAC) were measured in the temperature range of 373 K-1173 K. Thermal conductivity values as low as 0.17 W/m K and 0.32 W/m K for FAC and FA respectively at 1200 K were found. These results confirm their potentiality as ultra-low thermal conductivity thermal insulators for high temperature applications. © 2012 Elsevier Ltd. All rights reserved.

Burrola-Gandara L.A.,Research Center en Materiales | Santillan-Rodriguez C.R.,Research Center en Materiales | Rivera-Gomez F.J.,Research Center en Materiales | Saenz-Hernandez R.J.,Research Center en Materiales | And 2 more authors.
Journal of Applied Physics | Year: 2015

Magnetocaloric materials with second order phase transition near the Curie temperature can be described by critical phenomena theory. In this theory, scaling, universality, and renormalization are key concepts from which several phase transition order criteria are derived. In this work, the rescaled universal curve, Banerjee and mean field theory criteria were used to make a comparison for several magnetocaloric materials including pure Gd, SmCo1.8Fe0.2, MnFeP0.46As0.54, and La0.7Ca0.15Sr0.15MnO3. Pure Gd, SmCo1.8Fe0.2, and La0.7Ca0.15Sr0.15MnO3 present a collapse of the rescaled magnetic entropy change curves into a universal curve, which indicates a second order phase transition; applying Banerjee criterion to H/σ vs σ2 Arrot plots and the mean field theory relation |ΔSM| (μ0H/Tc)2/3 for the same materials also determines a second order phase transition. However, in the MnFeP0.46As0.54 sample, the Banerjee criterion applied to the H/σ vs σ2 Arrot plot indicates a first order magnetic phase transition, while the mean field theory prediction for a second order phase transition, |ΔSM| (μ0H/Tc)2/3, describes a second order behavior. Also, a mixture of first and second order behavior was indicated by the rescaled universal curve criterion. The diverse results obtained for each criterion in MnFeP0.46As0.54 are apparently related to the magnetoelastic effect and to the simultaneous presence of weak and strong magnetism in Fe (3f) and Mn (3g) alternate atomic layers, respectively. The simultaneous application of the universal curve, the Banerjee and the mean field theory criteria has allowed a better understanding about the nature of the order of the phase transitions in different magnetocaloric materials. © 2015 AIP Publishing LLC.

Morales-Meza S.,Research Center en Materiales | Sanchez-Castro M.E.,Research Center Estudios | Sanchez M.,Research Center en Materiales
Journal of Molecular Modeling | Year: 2013

In this work we have performed a systematic study of new organometallic complexes containing penta- and heteropentadienyl (CH2CHCHCHX, X = CH2, O, NH, S) ligands coordinated to beryllium. Calculated complexes were studied using the density functional theory (PBE) in combination with the 6-311++G(3d,2p) basis set. The coordination number on the beryllium atom varies according to the type of ligand. Pentadienyl ligand shows hapticities η1 and η5, while heteropentadienyl ligands display η1 and η2 hapticities. A Wiberg bond indices study was performed in order to get information about their bond orders. [Figure not available: see fulltext.] © 2013 Springer-Verlag Berlin Heidelberg.

Loading Research Center en Materiales collaborators
Loading Research Center en Materiales collaborators