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, Angélica María. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Morales, Gustavo Marcelo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Barbero, César Alfredo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Planes, Gabriel Angel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; 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. UV–Vis 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

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 Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Baena Moncada, Angélica María. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Tamborini, Luciano Henri. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Coneo Rodríguez, Rusbel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Planes, Gabriel Angel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Morales, Gustavo Marcelo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Acevedo, Diego Fernando. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Balach, Juan Manuel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Bruno, Mariano Martín. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Barbero, César Alfredo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; Argentin

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 (Δginter) 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.Revisión 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 g−1 lower than the commercial catalyst PtRu/E-tek (107.2 m2 g−1); 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, Angélica María. Universidad Nacional de Ingenieria; PerúFil: Bazan-Aguilar, Antony. Universidad Nacional de Ingenieria; PerúFil: Pastor, Elena. Universidad de La Laguna; EspañaFil: Planes, Gabriel Angel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; Argentin

Diseño y construcción de una unidad de tratamiento de agua autónoma basada en iones ferrato(VI), energizada por paneles fotovoltaicos

Una unidad de tratamiento avanzado de agua que utilice energía solar es una solución ventajosa para zonas remotas con alta irradiación solar, lo que incluye poblados, operaciones y pasivos mineros. Dicha unidad debe ser autónoma, lo que implica el control automatizado de la secuencia de procesos de purificación de agua y la independencia de la red eléctrica. Por ello, se plantea el diseño y construcción de una unidad de tratamiento de agua autónoma y compacta que, utilizando iones ferrato generados electroquímicamente e integrados a un sistema, dosifique los iones con base en las necesidades del agua, ajuste el pH, remueva los contaminantes y produzca agua cuya calidad pueda ajustarse a la necesidad que busca resolverse: generación de agua potable o tratamiento de agua residual

SENSOR POTENCIOMÉTRICO BASADO EN NANOPARTÍCULAS DE SULFURO DE PLATA SOPORTADAS EN MATERIALES CARBONOSOS PARA LA DETECCIÓN DE CIANURO LIBRE

Two sensors were synthesized for the detection of free cyanide (CN-), based on silver sulfide nanoparticles (Np-Ag2S) supported on Multiwall Carbon Nanotubes (MWCNT) and hierarchical porous carbon (HPC). The Ag2S/HPC400 and Ag2S/MWCNT were characterized by physicochemical techniques such as Raman spectroscopy, X-Ray diffraction (XRD) and Scanning electron microscopy (SEM). These sensors were evaluated against the detection of free cyanide by potentiometry; the stability, reproducibility and linearity of each sensor were determined. A limit of detection of 3.34 µg L-1 and a limit of quantification of 11.05 µg L-1 for Ag2S/HPC400 sensor was obtained; while for the Ag2S/MWCNT sensor a limit of detection and limit of quantification value of 23.17 µg L-1 and 76.46 µg L-1 were obtained, respectively. The results show that the presence of carbonaceous materials with a hierarchical structure improves the limits of quantification and detection of the Ag2S/HPC400 sensor

Electrocatalysis of As(III) oxidation by cobalt oxide nanoparticles: measurement and modeling the effect of nanoparticle amount on As(III) oxidation potential

The performance of electrodes modified with electrochemically generated cobalt oxide nanoparticles for the oxidation of As(III) species was investigated by cyclic voltammetry (CV) and rotating disk voltammetry (RDV). The oxide nanoparticles were made by electrodeposition from cobalt oxides using CV without the reduction of water or anions. Controlling deposition parameters, different values of surface concentration (Γ) can be obtained. Electrochemical experiments (CV and RDV at different rotation rate) showed a shift in the As(III) oxidation potentials to lower values; when the coverage surface increased, these differences in the surface concentration produced a potential shift of up to 150 mV. This phenomenon depends on the ratio of the electrode active area to the geometric area (Ψ). The Levich and Koutecký-Levich analysis of RDV voltammetric data confirmed that the oxidation of As(III) on modified electrodes is controlled by mass transport. It was also demonstrated that different values of surface concentration produces different kinetic current values.Fil: Coneo Rodriguez, Rusbel. Comisión Nacional de Energia Atomica. Gerencia D/area de Seguridad Nuclear y Ambiente; ArgentinaFil: Baena Moncada, Angélica María. Universidad Nacional de Ingeniería. Facultad de Ciencias; PerúFil: Acevedo, Diego Fernando. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química y Física; ArgentinaFil: Morales, Gustavo Marcelo. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química y Física; ArgentinaFil: Planes, Gabriel Angel. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química y Física; ArgentinaFil: Barbero, César Alfredo. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química y Física; Argentin