Insights in Pt-based electrocatalysts on carbon supports for electro-oxidation of carbohydrates: an EIS-DEMS analysis

In this work, the electrochemical oxidation of carbohydrates (glucose, fructose, and sucrose) was induced at the interface of Pt-nanoparticles supported on different carbon-based materials as carbon vulcan (C) and carbon black (CB). It was found that the support plays an important role during carbohydrates electro-oxidation as demonstrated by electrochemical techniques. In this context, current-concentration profiles of the redox peaks show the behavior of the pathways at carbohydrates-based solutions. Herein, the trend of current measured was glucose > sucrose > fructose, attributed to differences in the organic functional groups and chain-structure. Raman, XRD, SEM-EDS and XPS put in clear important structural, morphological, and electronic differences linked with the intrinsic nature of the obtained material. Differential Electrochemical Mass Spectroscopy (DEMS) indicated that the selectivity and the conversion of the formed reaction products during oxidation is linked with the catalyst nature (distribution, particle size) and the interaction with the carbon-based support

The Cerium/Boron Insertion Impact in Anatase Nano-Structures on the Photo-Electrochemical and Photocatalytic Response

Boron- and cerium-doped titania (Anatase) were prepared via sol-gel method. Phase composition and morphology were assessed by X-ray diffraction (XRD), scanning electronic microscopy (SEM), BET, diffuse reflectance spectra (DRS), and XPS. Photo-electrochemistry of these materials, deposited onto fluorine-doped SnO2 (FTO), was investigated in acid and acid-containing methanol. The boron-doped sample showed the best opto-electronic properties among the investigated samples. On the other hand, the cerium-doped titania samples annihilate to a certain extent the titania surface states, however, photogenerated charge separation was limited, and certainly associated to surface Ce3+/Ce4+ species. The substitutional effect of boron ions for O sites and interstitial sites was confirmed by XRD and XPS analyses

Electroreduction of NOxz species in alkaline medium on Pt nanoparticles

International audienceThe electroreduction of nitrogen species in alkaline medium was performed on platinum nanoparticles (1-2 nm) with metal loadings of 5 and 10 wt% Pt, synthesized by the chemical carbonyl route. The electrochemically active surface analysis evidences that the real surface area is concomitant to the Pt-loading in the support. The electrochemical analysis put in evidence that nitrite ions were reduced from -0.6 to -0.78 V and the charge transfer step is attributed to the NO2-/NO redox couple. The Tafel slope analysis confirms that from E-p to -0.78 V the reduction of NO occurs via an ECE mechanism. An analysis of Nicholson-Shain schemes and NO-saturated in solution verified these results. (C) 2012 Elsevier Ltd. All rights reserved

Emprendiendo San Lucas Evangelista

Documento que presenta los objetivos, actividades, alcances, productos y conclusiones del Proyecto de Aplicación Profesional realizado en la localidad de San Lucas Evangelista en el municipio de Tlajomulco de Zúñiga. El objetivo fue fortalecer las capacidades individuales, técnicas y sociales de las personas que emprenden proyectos en las localidades de la Ribera de Cajititlán. Se realizaron sesiones presenciales con los emprendedores de San Lucas Evangelista y se les ayudó en la elaboración de su plan de negocio. En este proyecto trabajaron juntos alumnos de Ingeniería Industrial, de la licenciatura en Administración de Empresas y de Relaciones Internacionales

Emprendiendo San Lucas Evangelista

Documento que presenta los objetivos, actividades, alcances, productos y conclusiones del Proyecto de Aplicación Profesional realizado en la localidad de San Lucas Evangelista en el municipio de Tlajomulco de Zúñiga. El objetivo fue fortalecer las capacidades individuales, técnicas y sociales de las personas que emprenden proyectos en las localidades de la Ribera de Cajititlán. Se realizaron sesiones presenciales con los emprendedores de San Lucas Evangelista y se les ayudó en la elaboración de su plan de negocio. En este proyecto trabajaron juntos alumnos de Ingeniería Industrial, de la licenciatura en Administración de Empresas y de Relaciones Internacionales

Improved methanol electro-oxidation reaction on PdRh-PVP/C electrodes

International audienceHere we report on the organometallic synthesis of polyvinylpyrrolidone (PVP)-stabilized palladium-rhodium nanostructures that display high electrochemical properties when used as carbon-supported electrodes (PdxRh1-x-PVP/C) for methanol oxidation reaction (MOR). These nanostructures were synthesized by hydrogenation of the tris(dibenzylideneacetone)dipalladium(0) (Pd2(dba)3) and tris(allyl) rhodium (Rh(η3-C3H5)3) complexes, in tetrahydrofuran (THF) under mild reaction conditions (room temperature and 3 bar H2) and in the presence of PVP as stabilizer. The influence of methanol concentration (0.5, 1.0 and 2.0 M) as well as different scan rates (5–100 mV s−1) was evaluated to determine changes in the stability and catalytic activity. The organometallic approach and the use of PVP for the preparation of PdRh electrode materials promoted the formation of highly dispersed nanostructures, that led to a remarkably enhanced methanol electro-oxidation in alkaline medium. This high catalytic behavior can reasonably arise from a synergistic effect between Pd and Rh metals as, under the applied conditions, Rh is expected to enhance the Pd ability to oxidize methanol to CO2 (oxophilic character) as well as the catalyst stability. From all the evaluated electrode materials, Pd8Rh2-PVP/C electrode showed the highest mass activity at high methanol concentration (2.0 M) and low scan rate (10 mV s−1). This catalyst showed a performance up to 26 times higher than that of Pd-PVP/C and interestingly an electroactivity superior to that of previously reported PdRh catalysts

Pd and Pd@PdO core–shell nanoparticles supported on Vulcan carbon XC-72R: comparison of electroactivity for methanol electro-oxidation reaction

International audienceNanomaterials based on Pd nanoparticles supported on Vulcan carbon (XC-72R) were prepared by the organometallic approach in one-pot and mild conditions (3 bar hydrogen and room temperature) using Pd(dba)2 (bis (dibenzylideneacetone) palladium (0)) as metal source and hexadecylamine (HDA) as stabilizer. High-resolution transmission electron microscopy (HR-TEM) evidenced the presence of well-dispersed Pd nanoparticles of ca. 4.5 nm mean size onto the carbon support (Pd/HDA/C). Scanning and transmission electron microscopy with electron energy loss spectroscopy (STEM-EELS) allowed to determine the chemical composition of the nanomaterials. When the Pd/HDA/C nanomaterial was submitted to heating treatment (ht) at 400 °C under air (referred as Pd/HDA/C@air-ht), X-ray photoelectron spectroscopy (XPS) and HR-TEM/STEM-EELS analyses suggested the presence of interactions between PdO and Pd(0) as a result of the formation of Pd@PdO core–shell nanoparticles. The highest oxidation current magnitude during methanol oxidation reaction is ascribed to the heat-treated material, linked with a better electron and mass transfer processes at the electrode interface. This can be attributed to electronic interactions at the core–shell formed, which might promote different redox processes at the electrode interface during CH3OH deprotonation in the alkaline electrolyte