35 research outputs found
Formic acid oxidation over hierarchical porous carbon containing PtPd catalysts
The use of high surface monolithic carbon as support for catalysts offers important advantage, such as elimination of the ohmic drop originated in the interparticle contact and improved mass transport by ad-hoc pore design. Moreover, the approach discussed here has the advantage that it allows the synthesis of materials having a multimodal porous size distribution, with each pore size contributing to the desired properties. On the other hand, the monolithic nature of the porous support also imposes new challenges for metal loading. In this work, the use of Hierarchical Porous Carbon (HPC) as support for PtPd nanoparticles was explored. Three hierarchical porous carbon samples (denoted as HPC-300, HPC-400 and HPC-500) with main pore size around 300, 400 and 500 nm respectively, are used as porous support. PtPd nanoparticles were loaded by impregnation and subsequent chemical reduction with NaBH4. The resulting material was characterized by EDX, XRD and conventional electrochemical techniques. The catalytic activity toward formic acid and methanol electrooxidation was evaluated by electrochemical methods, and the results compared with commercial carbon supported PtPd. The Hierarchical Porous Carbon support discussed here seems to be promising for use in DFAFC anodes.Fil: Baena Moncada, AngĂ©lica MarĂa. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Departamento de QuĂmica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Morales, Gustavo Marcelo. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Departamento de QuĂmica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Barbero, CĂ©sar Alfredo. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Departamento de QuĂmica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Planes, Gabriel Angel. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Departamento de QuĂmica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Florez Montano, Jonathan. Universidad de la Laguna; EspañaFil: Pastor, Elena. Universidad de la Laguna; Españ
Effect of palladium on gold in core-shell catalyst for electrooxidation of ethanol in alkaline medium
In this paper the effect of small amounts of palladium deposited on gold nanoparticles supported on Vulcan XC-72 carbon (core-shell structure denoted Au@Pd/C) is studied. Different nominal atomic compositional ratios of Au@Pdx maintaining fixed gold nuclei and varying the amount of palladium (x = 0.10; 0.80 and 1.60) were synthesized via seed growth method for the ethanol oxidation reaction in alkaline medium. UVâVis spectrometric, X-ray powder diffraction, X-ray energy dispersive spectroscopy, transmission electron microscopy and electrochemical measurements were performed for the characterization of these catalysts. Electrocatalytic activity toward ethanol oxidation on Au@Pd/C catalysts were investigated by cyclic voltammetry and chronoamperometry showed that [email protected]/C electrocatalyst has the highest current density and low onset potential for ethanol oxidation reaction in alkaline medium. In-situ Fourier transform infrared spectroscopy measurements demonstrated that acetate is the main product of ethanol oxidation and CO2 can be slightest observed, the latter could be visualized in greater quantity on catalyst [email protected]/C catalyst
Biomass-Based Carbon Electrodes in the Design of Supercapacitors: An Electrochemical Point of View
The urgent demand of sustainable long-lasting batteries has fostered the improvement of extended-use technologies e.g., Li-ion batteries, as well as the development of alternative energy storage strategies like supercapacitors. In this context, new carbon-based materials were developed to attain higher electrochemical performances, even though several of these materials are not obtained by eco-friendly methods and/or in a considerable amount for practical purposes. However, up-to-date reports stand out the scopes achieved by biomass-based carbon materials as energy storage electrodes combining outstanding physicochemical and electrochemical properties with low-pollutant and low-cost production. On this basis, this chapter will expose several aspects of the synthesis of carbon-based electrodes from biomass, focusing on the influence of their surface properties: porosity, crystallinity, and morphology on their electrochemical performance in supercapacitors
Low-Scale Expression and Purification of an Active Putative Iduronate 2-Sulfate Sulfatase-Like Enzyme from Escherichia coli K12
The sulfatase family involves a group of enzymes with a large degree of similarity. Until now, sixteen human sulfatases have been identified, most of them found in lysosomes. Human deficiency of sulfatases generates various genetic disorders characterized by abnormal accumulation of sulfated intermediate compounds. Mucopolysaccharidosis type II is characterized by the deficiency of iduronate 2-sulfate sulfatase (IDS), causing the lysosomal accumulation of heparan and dermatan sulfates. Currently, there are several cases of genetic diseases treated with enzyme replacement therapy, which have generated a great interest in the development of systems for recombinant protein expression. In this work we expressed the human recombinant IDS-Like enzyme (hrIDS-Like) in Escherichia coli DH5α. The enzyme concentration revealed by ELISA varied from 78. 13 to 94. 35 ng/ml and the specific activity varied from 34. 20 to 25. 97 nmol/h/mg. Western blotting done after affinity chromatography purification showed a single band of approximately 40 kDa, which was recognized by an IgY polyclonal antibody that was developed against the specific peptide of the native protein. Our 100 ml-shake-flask assays allowed us to improve the enzyme activity seven fold, compared to the E. coli JM109/pUC13-hrIDS-Like system. Additionally, the results obtained in the present study were equal to those obtained with the Pichia pastoris GS1115/pPIC-9-hrIDS-Like system (3 L bioreactor scale). The system used in this work (E. coli DH5α/pGEX-3X-hrIDS-Like) emerges as a strategy for improving protein expression and purification, aimed at recombinant protein chemical characterization, future laboratory assays for enzyme replacement therapy, and as new evidence of active putative sulfatase production in E. coli. © 2013 The Microbiological Society of Korea and Springer-Verlag Berlin Heidelberg.Fil: Morales Ălvarez, Edwin David. Universidad del Quindio; ColombiaFil: Rivera Hoyos, Claudia Marcela. Universidad del Quindio. Facultad de Medicina; ColombiaFil: Baena Moncada, Angelica Maria. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba; ArgentinaFil: LandĂĄzuri, Patricia. Universidad del Quindio. Facultad de Medicina. Centro de Investig. BiomĂ©dicas; ColombiaFil: Poutou Piñales, RaĂșl A.. Pontificia Universidad Javeriana; ColombiaFil: SĂĄenz SuĂĄrez, Homero. Universidad del Quindio; ColombiaFil: Barrera, Luis A.. Pontificia Universidad Javeriana; ColombiaFil: Echeverri Peña, Olga Y.. Pontificia Universidad Javeriana; Colombi
Carbon Nanomaterials: A versatile platform for energy technologies
Carbon nanomaterials play an important role in the development of alternative clean and sustainable energy technologies. These materials are a fascinating subject of study themselves, not only for its good chemical and mechanical stability, good electrical conductivity, high specific surface area and controlled pore size, but also because the pore structure can be further modified by active functional groups for the construction of more complex systems with a broad umbrella of applications. Furthermore, the surface chemistry, the morphology and the structural properties of the carbonaceous materials can be controlled by the judicious choice of the carbon precursor material and the route of fabrication. This minireview article spotlights the recent research progress on the synthesis of porous carbon nanomaterials and its application in energy storage and conversion. Particularly, we will discuss the synthesis and applications of mesoporous carbons as functional separator coatings in lithium-sulfur batteries, nanostructured carbons as catalyst supports for fuel cells and functionalized porous carbons as an acid catalyst for biofuel generation. Concluding the minireview, prospects for the future development of practical carbon nanomaterials are discussed.Fil: Zensich, Maximiliano Andres. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados. - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados; ArgentinaFil: Baena Moncada, AngĂ©lica MarĂa. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados. - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados; ArgentinaFil: Tamborini, Luciano Henri. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados. - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados; ArgentinaFil: Coneo RodrĂguez, Rusbel. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados. - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados; ArgentinaFil: Planes, Gabriel Angel. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados. - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados; ArgentinaFil: Morales, Gustavo Marcelo. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados. - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados; ArgentinaFil: Acevedo, Diego Fernando. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados. - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados; ArgentinaFil: Balach, Juan Manuel. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados. - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados; ArgentinaFil: Bruno, Mariano MartĂn. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados. - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados; ArgentinaFil: Barbero, CĂ©sar Alfredo. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados. - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados; Argentin
Nitrogen-doped porous carbons from bipyridine-based metal-organic frameworks: Electrocatalysis for oxygen reduction reaction and Pt-catalyst support for methanol electrooxidation
Formic Acid Oxidation over Hierarchical Porous Carbon Containing PtPd Catalysts
The use of high surface monolithic carbon as support for catalysts offers important advantage, such as elimination of the ohmic drop originated in the interparticle contact and improved mass transport by ad-hoc pore design. Moreover, the approach discussed here has the advantage that it allows the synthesis of materials having a multimodal porous size distribution, with each pore size contributing to the desired properties. On the other hand, the monolithic nature of the porous support also imposes new challenges for metal loading. In this work, the use of Hierarchical Porous Carbon (HPC) as support for PtPd nanoparticles was explored. Three hierarchical porous carbon samples (denoted as HPC-300, HPC-400 and HPC-500) with main pore size around 300, 400 and 500 nm respectively, are used as porous support. PtPd nanoparticles were loaded by impregnation and subsequent chemical reduction with NaBH4. The resulting material was characterized by EDX, XRD and conventional electrochemical techniques. The catalytic activity toward formic acid and methanol electrooxidation was evaluated by electrochemical methods, and the results compared with commercial carbon supported PtPd. The Hierarchical Porous Carbon support discussed here seems to be promising for use in DFAFC anodes
Revisiting the Sweet Taste Receptor T1R2-T1R3 through Molecular Dynamics Simulations Coupled with a Noncovalent Interactions Analysis
It is nowadays widely accepted that sweet taste perception is elicited by the activation of the heterodimeric complex T1R2-T1R3, customarily known as sweet taste receptor (STR). However, the interplay between STR and sweeteners has not yet been fully clarified. Here through a methodology coupling molecular dynamics and the independent gradient model (igm) approach we determine the main interacting signatures of the closed (active) conformation of the T1R2 Venus flytrap domain (VFD) toward aspartame. The igm methodology provides a rapid and reliable quantification of noncovalent interactions through a score (Îginter) based on the attenuation of the electronic density gradient when two molecular fragments approach each other. Herein, this approach is coupled to a 100 ns molecular dynamics simulation (MD-igm) to explore the ligand-cavity contacts on a per-residue basis as well as a series of key inter-residue interactions that stabilize the closed form of VFD. We also apply an atomic decomposition scheme of noncovalent interactions to quantify the contribution of the ligand segments to the noncovalent interplay. Finally, a series of structural modification on aspartame are conducted in order to obtain guidelines for the rational design of novel sweeteners. Given that innovative methodologies to reliably quantify the extent of ligand-protein coupling are strongly demanded, this approach combining a noncovalent analysis and MD simulations represents a valuable contribution, that can be easily applied to other relevant biomolecular systems.RevisiĂłn por pare
Methanol conversion efficiency to CO2 on PtRu nanoparticles supported catalysts, a DEMS study
A comparative study of the use of PtRu nanoparticles supported on hierarchical porous carbons with different pore sizes for CO2 production efficiency during methanol electro-oxidation was performed by Differential Electrochemical Mass Spectrometry. The supported catalyst PtRu/HPC400 presented an ESA of 82.56 m2 gâ1 lower than the commercial catalyst PtRu/E-tek (107.2 m2 gâ1); however, it has higher performance for methanol electro-oxidation. Methanol conversion efficiency reaches values higher than PtRu/E-tek commercial catalyst, 93.17% for PtRu/HPC400 versus 41.36% for PtRu/E-tek, under potentiodynamic conditions. The hierarchical porous carbons interconnected channels improve the mass transport process.Fil: Baena Moncada, AngĂ©lica MarĂa. Universidad Nacional de Ingenieria; PerĂșFil: Bazan-Aguilar, Antony. Universidad Nacional de Ingenieria; PerĂșFil: Pastor, Elena. Universidad de La Laguna; EspañaFil: Planes, Gabriel Angel. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados. - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones en TecnologĂas EnergĂ©ticas y Materiales Avanzados; Argentin
A novel method to produce a hierarchical porous carbon as a conductive support of PtRu particles. Effect on CO and Methanol electrooxidation
The fabrication and catalytic properties of hierarchical porous carbon loaded with PtRu particles was studied. A silica nanoparticles opal is filled with resorcinol/formaldehyde resin, which is then pyrolized to form a macroporous carbon. Depending on synthesis conditions the volume contraction induces mesopore formation in the macroporous carbon, creating a hierarchical porous carbon (HPC). The material consists of a thick, highly porous electrocatalytic film. PtRu nanoparticles were loaded inside the HPC by reduction of metallic ions with formic acid. The electrocatalytic activity toward CO and methanol oxidation was evaluated. The current densities for methanol electrooxidation at 60 °C (220 ÎŒA cm -2 and 120 Ag -1 at 0.55 V RHE) reveals high activity, suggesting that the catalysts consist of well disperse, small PtRu nanoparticles, with a low degree of agglomeration and good accessibility for reactants.Fil: Baena Moncada, Angelica Maria. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba; Argentina. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Departamento de QuĂmica. Ărea ElectroquĂmica; ArgentinaFil: Planes, Gabriel Angel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba; Argentina. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Departamento de QuĂmica. Ărea ElectroquĂmica; ArgentinaFil: Moreno, Mario Sergio Jesus. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Patagonia Norte; Argentina. ComisiĂłn Nacional de EnergĂa AtĂłmica. Centro AtĂłmico Bariloche; ArgentinaFil: Barbero, CĂ©sar Alfredo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba; Argentina. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas FisicoquĂmicas y Naturales. Departamento de QuĂmica. Ărea ElectroquĂmica; Argentin