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4 figuras [EN] The application of batteries coupled to renewable energy conversion systems in cities will greatly help to overcome some of the technological challenges for grid electrification and transport, such as difficult accessibility to charging points, and cost, by improving their technical capabilities and making the energy system globally more sustainable. Furthermore, its implementation will have an immediate effect on citizens’ health due to the reduction of greenhouse gas emissions into the atmosphere, as well as other pollutants. Below is a review of recent efforts to develop new advanced technologies for future sustainable batteries. We will also highlight current battery recycling strategies that are being implemented towards a zero-carbon future based on the concept of the circular economy. [ES] La aplicación de baterías acopladas a sistemas de conversión de energía renovable en las ciudades ayudará en gran medida a superar algunos de los retos tecnológicos para la electrificación de la red y el transporte, como la difícil accesibilidad a puntos de carga, y de coste, mejorando sus capacidades técnicas y haciendo que el sistema energético a nivel global sea más sostenible. Además, su aplicación tendrá un efecto inmediato en la salud de los ciudadanos debido a la disminución de las emisiones de gases de efecto invernadero a la atmósfera, así como otros contaminantes. A continuación, presentamos una revisión de los esfuerzos recientes para desarrollar nuevas tecnologías avanzados para las futuras baterías sostenibles. También destacaremos las estrategias actuales de reciclado de baterías que se aplican hacia un futuro con cero emisiones de carbono y basado en el concepto de economía circular.

1 figure.--P32.-- Abstract of the poster presented at the CESEP’19 Conference: 8th International Conference on Carbon for Energy Storage and Environment Protection, October 20-24th, Alicante (Spain).-- © Universidad de Alicante., Metal-air batteries (MABs) are foreseen as a new generation device aiming to replace Li-ion batteries (LIBs). MABs present a higher theoretical energy density, lower cost, environmental friendliness, and safety. In particular, iron-based materials are cheap and easily obtained, and so they can be used for both the negative electrode and the positive electrode in MABs [1]. Here, Fe-doped carbon xerogels were synthesized in order to be tested as both positive and negative electrodes of iron-air batteries., The authors thank Gobierno de Aragón for their economical support to Grupo de Conversión de Combustibles (T06_17R). C. Alegre acknowledges CSIC for her Juan de la Cierva contract.

5 figures, 2 tables., In the present work, Pd and PdFe nanoparticles supported on CNT with and without functionalization (CNT and CNTox) were used for Formic Acid Oxidation Reaction (FAOR) in acid media. Electrocatalysts were synthesized by the borohydride reduction method with 20 wt.% metal loading. The CNTs were synthesized by the methane catalytic decomposition, and subjected to an oxidation treatment with nitric acid, named as CNTox. Themorphology, composition and structural properties were studied by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX) and X-Ray Diffraction (XRD). The FAOR was evaluated in acid media in a conventional three-electrode cell by means of cyclic voltammetry and chronoamperometry. From the steady state current density, it was found that Pd and PdFe supported at CNTox allowed improving the catalytic activity in comparison with the nonoxidized support., The authors thank the organizers of the meeting. LJM is grateful to CONACYT for the scholarship granted for the completion of the PhD studies and the ECS for the support given to attend the meeting. MGMOY, MARR, MEPP and EMAE thank the SNI for the distinction of their membership and the stipend received.

1 Figura.-- Presentado en las XXXVI Jornadas Nacionales de Ingeniería Química, JNIQ 2019, Zaragoza, 4-6 Sep. 2019., Las energías renovables son actualmente el modo más sostenible y limpio de producción de energía. Sin embargo, su naturaleza intermitente es uno de los factores limitantes para su mayor expansión e implementación en las redes de suministro eléctrico. Las baterías recargables son óptimas candidatas para el almacenamiento de dicha energía debido a su elevada eficiencia, su escalabilidad y flexibilidad1, siendo las baterías de flujo redox o las de plomo-ácido las más empleadas, junto con las baterías de ion litio, utilizadas principalmente en vehículos y dispositivos eléctricos. En las últimas décadas, la investigación en dispositivos de almacenamiento de energía se centra en desarrollar baterías de nueva generación con mayor potencia, mayor densidad energética y cuyos materiales sean seguros, económicos y abundantes. Las baterías metal-aire (MABs) pertenecen a esta nueva generación de baterías: con densidades de energía teóricas entre 1000 y 11000 Wh/kg (frente a los 250 Wh/kg aprox. de las baterías de ion litio), menores costes, y el uso de materiales abundantes, reciclables y sin los problemas de seguridad del litio 2. Las MABs generan electricidad a través de una reacción redox entre el metal (electrodo negativo) y el oxígeno del aire (que reacciona en el electrodo positivo), que, al no estar directamente almacenado en la celda, hace estas baterías mucho más ligeras. Existen diversos tipos de MABs, según sea el metal que empleen en el electrodo negativo: Zn, Al, Mg, Li, Na o Fe. De entre todos ellos, el sistema Fe-aire es uno de los más atractivos. El Fe es el cuarto elemento más abundante de la corteza terrestre, se produce en todo el mundo, su producción posee la menor huella de carbono de todos los metales, y, además, es fácilmente reciclable. Las baterías hierro-aire (FAB), con un voltaje de celda de 1,28 V, presentan hasta 764 Wh/kg de densidad de energía, así como la reversibilidad de la electroquímica del hierro, la simplicidad del diseño, y una gran durabilidad (resisten más de 1000 ciclos)3. No obstante, las FABs presentan una serie de retos que todavía requieren mayor investigación y desarrollo. El electrodo positivo debe ser un catalizador bifuncional, es decir, capaz de desarrollar la reducción de oxígeno (descarga) y la evolución de oxígeno (carga), ésta última con el problema añadido de su elevado potencial, lo que compromete la estabilidad de la mayoría de catalizadores, generalmente basados en materiales carbonosos4. Por otro lado, el electrodo negativo presenta una baja eficiencia culómbica de los ciclos carga-descarga (debido a la reacción parásita de evolución de hidrógeno, HER) y la pasivación del hierro (debida a la formación de productos de la descarga como Fe(OH)2 o FeOOH que no son conductores)3. Este trabajo tiene como objetivo investigar y desarrollar nanomateriales avanzados para la fabricación de electrodos negativos para baterías hierro-aire, compuestos de Fe, S y C. La idea principal es desarrollar composites basados en hierro de fácil obtención, dopados con azufre (para suprimir los problemas derivados de la HER) y soportados en materiales porosos y conductores, que eviten la pasivación del electrodo., Los autores agradecen la financiación de la Unión Europea, a través del proyecto NECOBAUT (New Concept of Metal-Air Battery for Automotive Application based on Advanced Nanomaterials). Grant agreement no: 314159. C. Alegre agradece al CNR-ITAE la beca Short-Term- Mobility para la Universidad de Southampton. Los autores agradecen al Gobierno de Aragón la financiación aportada al Grupo de Investigación Conversión de Combustibles (T06_17R). N. Villanueva agradece al Gobierno de Aragón la financiación de su contrato pre-doctoral.

Work presented at the CARBON 2019 conference, The World Conference on Carbon, 14th-19th july 2019, Lexington, Kentucky (U.S.A.).

6 Figuras, The World Conference on Carbon (Carbon 2018) was held on July 1–6, 2018, in Madrid, Spain (http: https://carbon2018.org/) organized by the Spanish Carbon Group. This Conference has been held for more than six decades, since the first celebrated in 1953 in Buffalo (USA). The Carbon 2018 has provided an opportunity, for a wide number of international experts, to discuss about the innovative and comprehensive overview of the latest research developments on carbon science and applications

1 figure.-- Poster presented at the 25th Topical Meeting of the International Society of Electrochemistry, "New electrochemical processes for energy and the environment", 12-15 May 2019, Toledo (Spain)., The growing energy worldwide requirements need of suitable facilities developments that allow the clean energy production through effective ways. In this sense, electrochemical devices, such as metal-air batteries, electrolyzers, polymeric fuel cells and regenerative fuel cells, appear as the real option to solve these energetic issues. However, the searching of active and stable oxygen electrodes toward oxygen evolution (OER) and oxygen reduction reactions (ORR) become an important challenge in performance enhancement terms. In addition, the use of noble metals like Pt, Ir and/or Ru represents a great barrier for their insertion to the market. In this study, graphenic materials (GMs) obtained from graphene oxide reduction using hydrazine (HrGO) or thiourea (SN-rGO) as reducing agents, as well as carbonaceous materials including carbon nanofibers (HC-CNF) and mesoporous carbon (g-CMK3) were synthesized, characterized and tested toward OER/ORR and compared to commercial carbon black (Vulcan) and graphite. Physicochemical characterization was conducted by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), elemental analysis and Raman spectroscopy. Besides, the catalytic performance toward ORR and OER in alkaline medium (0.1 M NaOH) was carried out by the rotating ring-disk electrode (RRDE) technique. Figure 1 indicates a profound impact of the carbonaceous structure on OER and catalyst stability. Graphenic materials mainly suffer corrosion at higher potentials than 1.0 V vs. RHE, while graphitic structures promote the oxygen evolution in basic media. Nevertheless, a possible influence of remaining metal impurities from the HC-CNF synthesis must be considered in these results.

Comunicación oral presentada en la Reunión Bienal de la Sociedad Española de Catálisis (SECAT 2019), celebrada en Córdoba, del 24 al 16 de junio de 2019.

8 Figures, 3 Tables.-- Supplementary material.-- © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/, We report the electrochemical properties of a novel nanocarbon material obtained by chemical oxidation and ultrasound-assisted exfoliation of fishbone carbon nanofibers (CNF). The resulting material maintains its tubular morphology and presents a characteristic interlayer spacing of graphene oxide (above 0.75 nm). Thus, this is called graphene oxide nanofibers (GONF). The new rearrangement of the accessible sp2-carbon domains makes the GONF a potential alternative for electrochemical energy conversion/storage applications, showing a developed porosity and tuneable surface chemistry. The influence of the oxidation degree of GONF on its electrochemical behaviour in 0.5 M H2SO4 is reported. Cyclic voltammetry and electrochemical impedance spectroscopy evidenced a significant increase of the capacitance for GONF, being 4–27 times higher than that obtained for pristine CNF. An optimum in the capacitance (49.2 F g−1) was obtained using an oxidation ratio (OR = KMnO4/Sample) of 6 and 60 min of sonication. The latter is ascribed to the unique structure of this material containing both graphitic and graphene oxide domains. Higher OR or longer sonication times led to a partial loss of graphitic domains and higher contribution of micropores, which worsen the fast ion/electrolyte transport. Additionally, the optimized material exhibited an improved activity for the hydrogen evolution reaction., This work was funded by FEDER, the Spanish Ministry of Science, Innovation and Universities MICINN (ENE2017-83976-C2-1-R & ENE2017-83854-R) and by the Aragón Government to the Fuel Conversion Group (T06_17R). DS thanks MICINN for his Ramon y Cajal research contract (RyC-2016-20944).

9 Figures, 3 Tables.-- Informacion suplementaria disponible en línea en la página web del editor.-- © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/, Nitrogen doped reduced graphene oxide (NrGO) catalysts and composites of these with carbon nitride (CN) with nitrogen content as high as 19.8 wt% and 35.8 wt%, respectively, have been synthesized by thermal annealing of multilayer graphene oxide and urea at different temperatures. Nitrogen has been effectively introduced as a mix of pyridinic, pyrrolic, pyridonic and quaternary bonding configurations into the carbon lattice of graphene upon removal of CN phase over 650 °C. The electrocatalytic activity towards oxygen reduction reaction (ORR) in 0.1 M NaOH has been investigated. NrGO catalysts with less nitrogen content show better performance than composites. NrGO produced at 800 °C presents the best activity with half-wave potential of 0.76 V vs. RHE and a mean number of electrons of 3.7, which are close to a commercial Pt/C catalyst. This study concludes that a high concentration of nitrogen atoms in multilayer reduced graphene oxide does not necessarily produce a highly active electrocatalyst, suggesting that carbon in the neighbourhood of nitrogen atoms are the active sites for ORR in alkaline medium., Authors acknowledge the financial support given by the Spanish Ministry of Science, Innovation and Universities (MICINN) through projects ENE2014-52158-C2-1-R and 2-R and ENE2017-83976-C2-1-R and 2-R (co-founded by FEDER) and Aragón Government to support “Grupo de Conversion de Combustibles” (T06_17R). G. Lemes and D. Sebastián thank the Aragón Government and MICINN for their Ph.D. grant and Ramón y Cajal research contract (RyC-2016-20944), respectively.

[EN] Carbon nanostructures have received increasing attention in electrocatalysis due to their surface electronic configuration with abundant π electrons which are beneficial for electron demanding reactions, like those occurring in electrochemical devices for the conversion or storage of energy, such as supercapacitors, batteries or fuel cells. While rechargeable batteries directly store and discharge electric power, fuel cells continuously convert the chemical energy of a fuel like hydrogen into electricity and heat. Both systems, along with supercapacitors, represent the ideal solution for non-polluting and highly efficient vehicles and power consumers. However, there are still some remaining technical challenges that these devices have in common: cost and durability are still far from practical application. In particular, some types of batteries and fuel cells share the common problem associated to the sluggishness of the oxygen reduction reaction (ORR). The ORR is the limiting process, determining the efficiency of these devices and requiring the use of noble metals of the platinum group (PGM) at the electrodes. Among the several strategies to replace PGM, doped carbon materials are a recent and unexplored alternative with great perspectives in terms of cost and availability, but yet poor activity and stability. In particular, graphene structures are expected to allow for the enhancement of the catalytic activity derived from its peculiar 2D morphology. There is still a great and recent controversy about the nature of active sites and the influence of non-noble metals like Fe or Co on the electro-catalytic activity. In any case, the presence of low atomic weight atoms, like nitrogen, as dopants in the catalyst matrix is essential to confer appropriate oxygen adsorption characteristics and sufficient catalytic activity. In this work, we will review the huge rise of research works on these catalysts for electrochemical devices in energy applications, in particular fuel cells and metal-air batteries. [ES] Las nanoestructuras de carbono han recibido una atención creciente en electrocatálisis debido a su configuración electrónica con abundantes electrones π que son beneficiosos para las reacciones que demandan electrones, como las que ocurren en dispositivos electroquímicos para la conversión o almacenamiento de energía, como baterías o pilas de combustible. Mientras que las baterías recargables almacenan y descargan directamente la energía eléctrica, las pilas de combustible convierten de modo continuo la energía química de un combustible como el hidrógeno en electricidad y calor. Ambos sistemas representan la solución ideal para vehículos y dispositivos que consumen energía, ya que son no contaminantes y son altamente eficientes. Sin embargo, aún quedan algunos desafíos técnicos que estos dispositivos tienen en común: su coste y durabilidad aún están lejos de resultar prácticos para su comercialización. La baja cinética de la reacción de reducción de oxígeno, que tiene lugar en el cátodo de las pilas de combustible, o en el electrodo positivo en algunos tipos de baterías, es un proceso limitante, que requiere el uso de electrodos basados en metales nobles como los del grupo del Pt (PGM). Los PGM son elementos escasos y con un coste muy elevado. Entre las diversas estrategias para reemplazar los PGM, los materiales de carbono dopados son una alternativa reciente y poco explorada, con excelentes perspectivas en términos de coste y disponibilidad, pero todavía no se ha alcanzado actividad y estabilidad suficiente. En particular, se espera que las estructuras basadas en grafeno permitan la mejora de la actividad catalítica derivada de su peculiar morfología 2D. Todavía hay una gran controversia sobre la naturaleza de los sitios activos y la influencia de los metales no nobles como Fe o Co en la actividad electro-catalítica. En cualquier caso, la presencia de átomos de bajo peso atómico, como el nitrógeno, como dopantes en la matriz carbonosa, es esencial para conferir características de adsorción de oxígeno apropiadas y suficiente actividad catalítica. En este trabajo, revisaremos el creciente interés en estos catalizadores para dispositivos electroquímicos con aplicaciones en energía.

1 figure.-- Poster presented at the VII International Symposium SRUK/CERU (2019), organized by the Society of Spanish Researchers in the United Kingdom. 28th-30th June 2019, Liverpool (United Kingdom)., The municipal solid waste (MSW) management is posing enormous environmental problems. An attractive strategy for MSW valorisation is to convert the carbon part into syngas, which may be further transformed into bio-fuels. However, some issues must be addressed, such as the low yield and the presence of sulphur compounds, which may poison the involved catalysts. The development of new desulfurization methods based on solid regenerable sorbents that can operate at high temperatures is an attractive strategy to overcome these problems. Mn oxides have been used as sulphur trapping sorbents due to their stability and high kinetics [1-2]. However, Mn oxides present unfavourable thermodynamics and stable sulfates are formed during the regeneration stage, decreasing the efficiency. In this work, the addition of Cu and/or Zn oxides has been proposed to overcome these limitations in regenerable sorbents., The authors gratefully acknowledge financial support given by Spanish MINECO and FEDER (PCIN 2015 222) through ERANET MED program and from Aragon Government to the Fuel Conversion Group.

6 Figuras.- 4 Tablas.- Datos suplementarios disponibles en línea en la página web del editor., Ordered mesoporous carbon materials (OMC), obtained by the template carbonization pathway from silica templates (sacrificial method), exhibit promising features for many applications mainly due to their large surface area. Graphitization is a common approach to improve the electrical conductivity and degradation resistance. We have investigated the graphitization of two different OMC at 1500 °C and the electrochemical oxidation by potential holding at 1.4 V vs. reversible hydrogen electrode (RHE) in acidic electrolyte. Graphitization conducts to a significant reduction of the electrooxidation associated charge, between 50 and 90% depending on the carbon properties, together with a decrease of surface area of 35–48%. The materials still exhibit a large electrochemical surface area, according to electrochemical impedance and cyclic voltammetry experiments. Upon electrooxidation, the relative amount of oxygen increases according to a comparative analysis of X-ray photoelectron spectroscopy test of the electrodes before and after potential holding. The results are of interest to define strategies towards the amelioration of carbon degradation by electrooxidation in electrochemical devices., The authors gratefully acknowledge financial support given by Spanish Ministry of Science, Innovation and Universities MICINN (ENE2017-83976-C2-1-R) and to the Aragón Government to the Fuel Conversion Group (T06_17R). DS acknowledges also MICINN for his Ramón y Cajal contract (RyC-2016-20944).

Poster presented at CARBON 2019, The world conference on carbon, 14th-19th july 2019, Lexington, Kentucky (U.S.A.), Electrocatalytic materials with high efficiency for the main reactions on bifunctional oxygen electrodes, the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), are necessary for the development of new emerging electrochemical energy storage and conversion devices. Although some noble metals such as Pt and metal oxides (RuO2, IrO2) possess excellent activity as electrocatalysts, their high cost and instability hinder large-scale applications. Tantalum-based materials have demonstrated to be active and robust electrocatalysts for the ORR in acidic environment1. They have an excellent electrochemical stability and become active for the oxygen reactions when the surface stoichiometry is tuned2. Carbon materials can act both as support and electron conductor phase. In this work, nanocomposites based on tantalum sub-oxides on carbon black have been investigated for the ORR and OER3., The authors wish to acknowledge the Ministerio de Ciencia, Innovación y Universidades (MICINN) and FEDER for the received funding in the project of reference ENE2017-83976-C2-1-R, as well as to the Gobierno de Aragón (DGA) and FEDER for the funding to Grupo de Investigación Conversión de Combustibles (T06_17R). J.C. Ruiz-Cornejo acknowledges also DGA his PhD grant. D. Sebastián acknowledges also MICINN for his Ramón y Cajal research contract (RyC-2016-20944).

1 figure.-- Abstract of the poster presented at the VII International Symposium SRUK/CERU (2019), organized by the Society of Spanish Researchers in the United Kingdom. 28th-30th June 2019, Liverpool (United Kingdom)., Graphene oxide nanomaterials, specifically reduced few-layer graphene oxide (rFLGO) sheets and reduced graphene oxide quantum dots (rGOQD), were explored as active and cost-effective counter electrodes for dye-sensitized solar cells (DSSCs). The synthesis strategy adopted in this work for these materials is based on an economic and easily scalable route of exfoliation of multi-wall carbon nanotubes (Top-Down approach). This allows the easy tailoring of rFLGO/rGOQD size and oxidation degree for their use as bulk material in counter electrodes, having a significant influence on the photovoltaic performance and stability. Despite the slower kinetics of carbon for the reduction of triiodide compared to platinum, they are characterized by low cost and promising stability. The electrochemical performance of DSSC assembled with either rFLGO or rGOQD at the counter electrode is correlated to their most important physico-chemical features. The domain size of graphene sheets had an important effect on the performance at the counter electrode, with quantum dots performing 13% higher efficiency than rFLGO, correlated with a higher density of active sites. Both graphene nanostructures exhibited a better stability behavior upon electrochemical cycling and seasoning of the cells as compared to Pt counter electrode., ICB-CSIC authors acknowledge the Raw Materials Network of Infrastructure ITO substitution in opto-electronic devices (European Union), and the funding of the FEDER and the Spanish Economy and Competitiveness Ministry (MINECO) (ENE2011-28318-C03-01 and ENE2014-52189-C02-01-R). JLP and DS thank MINECO for their Ramon y Cajal research contracts (RyC-2013-12494 and RyC-2016-20944). CNR-ITAE authors acknowledge the financial support from the FotoH2 project. This project has received funding from the European Union s Horizon 2020 research and innovation programme under Grant Agreement n° 760930.

1 figure.-- Talk delivered at the CESEP’19 Conference: 8th International Conference on Carbon for Energy Storage and Environment Protection, October 20-24th, Alicante (Spain).-- © Universidad de Alicante., The design of electrocatalytic materials with high efficiency and without noble metals for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are essential for the development of new emerging electrochemical energy storage and conversion devices [1]. Spent bleaching earth (SBE) is a worthless oil refinery waste material containing a notable percentage of residual oil. New applications are urgent such as converting SBE into catalysts, according to the circular economy concept. In this work SBE has been used as electrocatalytic component for the reversible oxygen electrode. SBE was chemically treated to obtain based-carbon compounds. Then, cobalt, iron and/or tungsten heteropolyacid were added to the carbon-based SBE compounds to obtain different composites. The textural, structural and surface chemistry properties of the composites materials were analysed along with electrochemical characterization in a three electrode cell in alkaline medium. Electrochemical results evidenced Co/SBE catalyst proved to be a valuable bifunctional competitor for ORR and OER showing activity in both reactions (Figure 1) and a better stability than Pt in accelerated tests., By the Spanish Ministry of Science, Innovation and Universities, through project ENE2017- 83976-C2-1-R (co-founded by FEDER), the Spanish National Research Council (CSIC) through project iCOOP20202 and MERC grant project 99392002. D. F.I. also thanks the CSIC for his JAE-Intro grant.

11 Figuras.- 2 Tablas.- Material suplementario disponible en línea en la página web del editor.-- Título del postprint: Crystal growth, structural phase transitions and optical gap evolution of CH3NH3Pb(Br1-xClx)3 powders, Chemically tuned inorganic–organic hybrid halide perovskites based on bromide and chloride anions CH3NH3Pb(Br1–xClx)3 have been crystallized and investigated by synchrotron X-ray diffraction (SXRD), scanning electron microscopy, and UV–vis spectroscopy. CH3NH3PbBr3 and CH3NH3PbCl3 experience successive phase transitions upon cooling, which are suppressed for intermediate compositions probably due to compositional disorder. For CH3NH3PbCl3, a transient phase, formerly described as tetragonal, was identified at 167.5 K; the analysis of SXRD data demonstrated that it is indeed orthorhombic, with space group Pnma, and a ≈ √2ap; b ≈ 2ap; c ≈ √2ap (ap is the ideal cubic perovskite unit-cell parameter). The band gap engineering brought about by the chemical management of CH3NH3Pb(Br1–xClx)3 perovskites can be controllably tuned: the gap progressively increases with the concentration of Cl ions from 2.2 to 2.9 eV, and shows a concomitant variation with the unit-cell parameters of the cubic phases at 295 K. This study provides an improved understanding of the structural and optical properties of the mixed CH3NH3Pb(Br1–xClx)3 perovskites., Authors acknowledge financial support given by KIC RAW MATERIALS from European Union (OPTNEWOPT project) and the Spanish Ministry of Economy and Competitiveness (ENE2014-52158-C2-1-R project and MAT2017-84496-R) cofounded by FEDER. C.A.L. acknowledges ANPCyT and UNSL for financial support (Projects PICT2014-3576 and PROICO 2-2016), Argentine. C.A.L. is a member of CONICET.

Póster presentado en el MABIC 2019, Metal-advanced Batteries International Congress, 6 y 7 de noviembre 2019, Pamplona.

The effect of chemical surface oxidation of the carbon black Vulcan XC-72R on the capacitance, tolerance to corrosion and electrochemical activity toward the hydrogen evolution reaction (HER) has been studied in 0.1 M NaHCO3. Acid treatments with HNO3 or a HNO3H2SO4 mixture resulted in a progressive introduction of oxygen-containing groups which led to a strong increase of the capacitance and a higher tendency to carbon corrosion. In contrast, an inhibition of the hydrogen evolution current (at potentials more negative than −1.0 V) was observed for oxidized samples in comparison to the un-treated material. HER was also tested in the presence of dissolved CO2 to study the influence of the surface chemistry on the CO2 electroreduction. An inhibition of the H2 evolution current was evidenced in the CO2 saturated electrolyte due to the adsorption of species from CO2 reduction. A strong hydrogen current decrease (65–78%), and thus a higher tendency to adsorb (CO2)red species, was obtained on the original Vulcan and the HNO3-treated samples, in comparison to the carbon oxidized with HNO3H2SO4 (15%), which could be related to the highest content of basic groups of the last carbon., The authors gratefully acknowledge financial support given by Spanish MINECO (ENE2014-52158-C2-1-R and 2-R). S. Pérez-Rodríguez thanks Gobierno de Aragón for the DGA grant. Furthermore, the authors wish to acknowledge Dra. Ana Beatriz García for the TPD measurements.

6 Figuras. 4 Tablas.-- Datos suplementarios sobre el artículo disponibles en la versión en línea del editor.-- © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/, This work reports a study of the electrical conductivity under compression of nanostructured carbon powders with different physicochemical properties (texture, chemical-surface and morphology): a commercial carbon black (Vulcan XC-72R) and synthesized ordered mesoporous carbon (OMC), carbon nanocoils (CNC) and carbon nanofibers (CNF). The electrical conductivity was determined from the sample resistance under compaction (from 0.5 to 140 MPa) using the four-probe technique. A comparison of intrinsic and grain electrical conductivities (calculated according to the percolation theory and the general effective media approximation) was performed. Additionally, samples were subjected to chemical oxidation or graphitization treatments to evaluate the effect of oxygen content and structural properties on the electrical conductivity. In spite of the physicochemical differences of carbon materials, an exponential decrease of the electrical conductivity with the oxygen amount was stated. Finally, thermal treatment of OMC at 1500 °C led to a surprising increase in its conductivity due to the graphitization of the amorphous carbon structure of the original material and the oxygen removal., The authors gratefully acknowledge financial support given by Spanish MINECO (ENE2014-52158-C2-1-R). Furthermore, the authors wish to thank Dra. Ana Beatriz García (INCAR-CSIC) for the graphitization treatment of OMC and the TPD measurements.

10 Figuras, 8 Tablas.-- Material suplementario disponible en línea en la página web del editor., The electrochemical oxidation of carbon represents a relevant limitation for the application of carbon-based materials at the electrodes of several electrochemical devices, like fuel cells, metal-air batteries, water electrolyzers or supercapacitors. Understanding the key influencing parameters is thus of paramount importance to prevent and avoid the degradation of carbon materials. In the present investigation, carbon xerogels (CXGs) as a model of synthetic amorphous carbon, were studied on the basis of different surface chemistry and structure. Electro-oxidation experiments consisted of potential holding (1.2 V vs. RHE) on electrodes prepared with CXGs. The results indicate that the presence of oxygen groups (-C-O) and a higher ordering degree hinder the carbon oxidation reaction. A sub-structural parameter considering both the amount of oxygen-free carbon atoms (C-C + C*-C-O) from X-ray photoelectron spectroscopy, and the disordering degree from Raman spectra (in terms of ID/IG) is here proposed as a new factor to evaluate the tendency of an amorphous carbon material, like xerogels, to be electrochemically oxidized., Authors acknowledge financial support given by Spanish Ministry of Science, Innovation and University (MICINN) through project ENE2017-83976-C2-1-R (co-founded by FEDER) and from Aragón Government to the Fuel Conversion Group. C. Alegre and D. Sebastián acknowledge also MICINN for their Juan de la Cierva (FJCI-2015-25560) and Ramón y Cajal (RyC-2016-20944) research contracts, respectively.

5 figures, 5 tables Carbon nanofibers (CNFs) have shown great potential in multiple applications. Their versatility is derived from the possibility of tuning their physical and chemical properties. CNFs can be synthesized using two main methods: the catalytic decomposition of carbon precursors or the electrospinning and carbonization of polymers. The most appropriate method relies on the desired characteristics of the CNFs. Some of their applications include the synthesis of catalysts and catalytic supports, as electrodes for fuel cell devices, in hydrogen storage systems, and in functional nanocomposites. In this review, recent advances in the synthesis and potential applications of CNFs are examined. The authors acknowledge the Ministry of Science, Innovation and University (MICINN) and FEDER for the financial support through the project SOL-CARE (PCIN2015_222) and from the Aragon government to the Fuel Conversion Group. J.C. Ruiz acknowledges the Aragon government for his PhD grant. D. Sebastián also acknowledges MICINN for his Ramón y Cajal contract (RyC-2016-20944).

Developing efficient, durable, and low cost catalysts based on earth-abundant elements for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is essential for renewable energy conversion and energy storage devices. We report herein a simple one-pot procedure for the synthesis of non-precious metals N-doped graphene composites employing urea as nitrogen source, and their application as bifunctional catalysts for both the ORR and OER in alkaline environment. In this study, the effects of the addition of Ti and Co on the structure and performance of the N-doped graphene composites are investigated. The incorporation of Ti leads to a composite with both anatase and rutile TiO2 crystalline phases as well as Ti3+ species stabilized upon hybridization with N-doped reduced graphene oxide. The ORR onset potential for the Ti-based composite is 0.85 V (vs. RHE) and the number of electrons transferred is 3.5, showing superior stability than Pt/C after accelerated potential cycling in alkaline solution. However, this composite shows low activity and stability for the OER. On the other hand, the composite consisting of metallic Co and Co3O4 nanocrystals grown on N-doped reduced graphene oxide exhibits the best performance as bifunctional catalyst, with ORR and OER onset potentials of 0.95 V and 1.51 V (vs. RHE), respectively, and a number of electrons transferred of 3.6 (ORR). The results reveal the presence of important structural features such as metallic Co as the predominant crystalline component, amorphous Co3O4 phase and the coordination of Co-N-doped graphene. All of them seem to be fundamental for the high activity and stability towards ORR and OER., Authors acknowledge financial support given by Spanish Ministry of Economy and Competitiveness (MINECO) through projects ENE2014-52158-C2-1-R and 2-R (co-founded by FEDER). J. M. Luque and G. Lemes also thank MINECO and Aragon Government, respectively, for their Ph.D. grants.

17 Figuras.-- Número del capítulo en postprint: 8, The electrochemical reduction of CO2 represents a promising alternative for obtaining a variety of useful products, with important applications in chemical industry or for power generation. However, finding an effective electrode for the activation and further reduction of CO2 continues being a key challenge. In addition, the reaction mechanism of the process and the involved intermediates are not fully clear as most works analyze the electrolysis products after CO2 reduction reaction, sampling the compounds in gas collectors or liquid solvents. With the main aim of generating knowledge, in situ techniques have been also used for the identification of the electrolysis products from CO2 reduction. Although these techniques are powerful tools for the elucidation of the reaction pathways, they are not commercial or recently introduced in the market and not-easy to use and, hence, these methods have not been widely employed. In the current chapter a review of the most commonly in situ techniques used for studying the CO2 electroreduction is addressed, paying special attention to the electrodes involved in the reaction. Furthermore, an explanation of the main experimental specifications is also described for an easier understanding of the method and a comparison of the in situ techniques, summarizing their advantages and disadvantages, is displayed., The authors gratefully acknowledge financial support given by Spanish MINECO (CTQ2011–28913–C02–01 and 02). GG acknowledges the Viera y Clavijo program (ACIISI & ULL) for financial support.

Nanocatalyst performance towards the ethanol oxidation reaction (EOR) for fuel cell applications can be enhanced by exploiting the benefits of structural and compositional sensitivity and control. We describe the synthesis and characterization of cubic Pt-Sn alloyed nanoparticles consisting of (100) faceted Pt-Sn nanoparticles with a core-shell structure, with a Pt-rich core and a Sn-rich shell. Stability tests indicated that this catalyst preserves its morphology and remains well-dispersed on the carbon support after 5,000 potential cycles, while a cubic (pure) Pt catalyst exhibited severe agglomeration of the nanoparticles after the same stability testing protocol. Analysis of the elemental distribution in the nanoparticles by STEM-EELS indicated that Sn dissolves from the outer part of the shell after potential cycling, forming a ~0.5 nm Pt skin. Finally, the activity of this bimetallic core-shell nanostructured electrocatalyst towards the EOR was investigated, exhibiting currents about three times higher than those of unshaped Pt-Sn nanoparticles and six times higher than Pt nanocubes., This work has been supported by Fundación Cajacanarias (project BIOGRAF), the Ministry of Economy and Competitiveness (MINECO) through the projects CTQ2011-28913-C02-02 and ENE2014-52158-C2-2-R (co-funded by FEDER) and the. The authors acknowledge the SEGAI services of Universidad de La Laguna for important technical assistance and R.R also thanks the funding received from MINECO (EEBB-I-16-11762) to carry out a predoctoral stay in a foreign R&D center. E.P. acknowledges support from an electron microscopy facilities supported by the NSF MRSEC program (DMR 1120296) and an NSF MRI grant (DMR 1429155).J.S.G. acknowledges financial support from VITC (Vicerrectorado de Investigación y Transferencia de Conocimiento) of the University of Alicante.

9 Figuras. 4 Tablas. Datos suplementarios pueden encontrarse en la versión en línea del editor., This work reports a study of the electrocatalytic properties and stability of nanostructured carbon electrodes by on-line differential electrochemical mass spectrometry (DEMS). A wide electrochemical characterization in 0.1 M NaHCO3 involving anodic (carbon corrosion and oxygen evolution reaction, OER) and cathodic (CO2 reduction and hydrogen evolution reaction, HER) key reactions in energy-conversion devices was performed. DEMS studies showed that the faradaic current from 1.3 to 1.6 V vs. RHE of carbons was only associated to CO2 formation by corrosion and not to OER, the stability being improved by the graphitic character of carbon. H2 evolution was also enhanced with graphitic carbon nanofilaments, even though metal traces might positively influence their catalytic activity. By comparison of the faradaic currents and the H2 formation signals, in the absence and presence of CO2, a high inhibition of the HER was established for all carbon electrodes due to the species adsorption from CO2 reduction., The authors gratefully acknowledge financial support given by Spanish MINECO (CTQ2011‐28913‐C02‐01 and 02). S. Pérez-Rodríguez acknowledges Gobierno de Aragón for the DGA grant.

8 Figuras, 1 Tabla, 2 Esquemas, The mechanism of CO and HCOOH electrooxidation in an acidic solution on carbon-supported Au–Pd core–shell nanoparticles was investigated by differential electrochemical mass spectrometry and in situ Fourier transform infrared (FTIR) spectroscopy. Analysis performed in nanostructures with 1.3 ± 0.1 nm (CS1) and 9.9 ± 1.1 nm (CS10) Pd shells provides compelling evidence that the mechanism of adsorbed CO (COads) oxidation is affected by structural and electronic effects introduced by the Au cores. In the case of CS10, a band associated with adsorbed OH species (OHads) is observed in the potential range of CO oxidation. This feature is not detected in the case of CS1, suggesting that the reaction follows an alternative mechanism involving COOHads species. The faradaic charge associated with COads oxidation as well as the Stark slope measured from FTIR indicates that the overall affinity and orbital coupling of CO to Pd are weaker for CS1 shells. FTIR spectroscopy also revealed the presence of HCOOads intermediate species only in the case of CS1. This observation allowed us to conclude that the higher activity of CS10 toward this reaction is due to a fast HCOOads oxidation step, probably involving OHads, to generate CO2. Density functional theory calculations are used to estimate the contributions of the so-called ligand and strain effects on the local density of states of the Pd d-band. The calculations strongly suggest that the key parameter contributing to the change in mechanism is the effective lattice strain., V.C. gratefully acknowledges the UK National Academy for their support through the International Newton Fellowship program (NF120002). D.P. and D.J.F. gratefully acknowledge funding from EPSRC (EP/K007025/1). J.J.L.H. is grateful for the Ph.D. scholarship partly funded by Sasol UK and NERC. E.P. acknowledges financial support from the Ministry of Economy and Competitiveness through Project ENE2014-52158-C2-2-R. D.J.F. is also grateful for the Research Fellowship from the Institute of Advanced Studies of the University of Bristol. TEM studies were performed at the University of Bristol Chemistry Imaging Facility with equipment funded by UoB and EPSRC (EP/K035746/1 and EP/M028216/1). We are grateful to Prof. Jeremy Sloan (University of Warwick, Coventry, U.K.) and Dr. Christoph Mitterbauer (FEI Co.) for the high-resolution TEM images of the CS1 nanoparticles. This work is part of the research network of the Deutsche Forschungsgemeinschaft FOR1376. E.S. acknowledges PIP-CONICET 112-201001-00411 and PICT 2012-2324; whereas P.M.Q. acknowledges PICT-2014-1084 (Agencia Nacional de Promoción Científica y Tecnológica, FONCYT, préstamo BID). A grant of computing time from the Baden-Württemberg grid is gratefully acknowledged. All the data presented in this paper can be freely accessed from the Bristol’s Research Data Repository (http://data/bris.ac.uk/10.5523/bris.1om4r04s216tn164tab9nfjyfg).

11 Figuras, 3 Tablas.-- Material suplementario disponible en línea en la página web del editor., Oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts play an important role in energy conversion and storage devices, but highly active and robust nonprecious metal catalysts are required to address the cost and durability issues. In this work, a modified gel methodology has been used to obtain nanocomposites of perovskite CoTiO3 and N-doped reduced graphene oxide (NrGO). Moreover, the influence of the annealing extent in the synthesis has been studied. The composites show higher activity in oxygen evolution and reduction reactions in alkaline environment compared to sole ilmenite, which is related to a strong interaction between cobalt titanate and NrGO carbon matrix. The annealing duration appears as a key variable to modulate the physicochemical properties and the electrochemical behavior. The composite prepared at the largest duration (3 h) exhibit enhanced bifunctional properties for ORR and OER, with onset potentials of 0.93 V and 1.53 V vs. RHE respectively, which is mainly attributed to higher concentration of nitrogen, larger extent of defects and/or the presence of more oxidized Co species in the nanocomposite., The authors wish to acknowledge the Ministerio de Ciencia, Innovación y Universidades (MICINN) and FEDER for the received funding in the project of reference ENE2017-83976-C2-1-R. Thanks also to the Gobierno de Aragón (DGA) the funding for the Grupo de Investigación Conversión de Combustibles (T06_17R). J. M. Luque also thanks MICINN for its Ph.D. grant. D. Sebastián acknowledges the MICINN for the contract Ramón y Cajal (RyC-2016-20944).

Carbon nanocoils (CNCs) synthesized via the catalytic graphitization of resorcinol formaldehyde gel were investigated as an electrocatalyst support in PEMFC anodes.Their textural and physical properties make them a highly efficient catalyst support for anodic hydrogen oxidation in low temperature PEMFC. When the oxidation of adsorbed CO was studied, a shift of 140 mV is observed compared with the commercial catalysts (Pt/C E-TEK) which is expected to be a key parameter in the fuel cell (PEM) performance. Furthermore, the behaviour of the electrocatalysts prepared was compared with that of a Pt/C E-TEK in a 5 cm2 PEM fuel cell. At room temperature, results showed a 4% increase in current density at 0.6 V in comparison with the Pt/C E-TEK electrocatalysts., The authors gratefully acknowledge financial support given by the Ministry of Economy and Competitiveness through the Projects CTQ2011-28913-C02-01 and -02. V. Celorrio also acknowledges CSIC and FSE for their JAE Grant; and the UK National Academy by the support though the Newton International Fellow program.

The electrooxidation of ethanol and carbon monoxide on Pt nanoparticles (NPs) supported on carbon nanofibers (CNFs) and carbon blacks (oxidized and non-oxidized) is studied. Quite similar characteristics are found for Pt NPs, including particle size and crystal phases, regardless of the nature of carbon support. Cyclic voltammetries and current-transient curves show higher ethanol oxidation current density for Pt/CNF than for Pt/Vulcan. In situ spectroelectrochemical techniques including Fourier transform infrared spectroscopy (FTIR) and differential electrochemical mass spectrometry (DEMS), are employed in order to identify adsorbed reaction intermediates and products. Pt/CNF results in a lower CO poisoning of the NP surface compared to Pt/Vulcan, allowing higher amount of free Pt active sites for the oxidation of ethanol which leads to the formation of acetic acid during the reaction., This work has been supported by Fundación Cajacanarias (project BIOGRAF) and the Ministry of Economy and Competitiveness (MINECO) through the project ENE2014-52158-C2-2-R and -1-R (co-funded by FEDER). The authors acknowledge the SEGAI services of Universidad de La Laguna for technical assistance and R.R also thanks the MINECO for the pre-doctoral grant.

Pt-Sn catalysts supported on carbon, with different Pt-Sn atomic ratios (3:1, 1:1, 1:3), were prepared through the formic acid method (FAM) and supported on different carbon supports (nanofibers and carbon blacks) to study their behavior toward CO stripping and ethanol oxidation reaction (EOR). PtSn/C catalysts and supports were physicochemically characterized by XRD, EDX, XPS, TEM and TPD. Good particle dispersion onto the carbon support, similar particle sizes (around 4-5 nm) and the presence of tin oxides were observed in all cases. Sn insertion favored the development of the Pt3Sn1 phase and the presence of higher oxidation states of both metals in the catalyst. Ethanol and adsorbed CO oxidation was studied at these materials both in acid and alkaline media, by linear sweep voltammetry and chronoamperometry. Higher EOR current densities were obtained with the increase in the amount of Sn in the samples, been those materials supported on CNF the ones with the best CO tolerance and catalytic activity toward this reaction. As expected, a great improvement of the EOR activity was found in alkaline media compare with sulfuric acid media, providing good expectative for these materials as catalysts for alkaline direct ethanol fuel cells., This work has been supported by Fundación Cajacanarias (project BIOGRAF) and the Ministry of Economy and Competitiveness (MINECO) through the projects CTQ2011-28913- C02-02 and ENE2014-52158-C2-2-R. R.R. is also indebted with the MINECO for the pre-doctoral grant.

6 Figures, 4 Tables.-- Work presented at the 5th Iberian Symposium on Hydrogen, Fuel Cells and Advanced Batteries (HYCELTEC 2015), 5-8 July 2015, Tenerife, Spain, The graphitisation of ordered mesoporous carbons (CMK-3) was carried out by thermal treatments under different conditions of temperature and heating rate. The electrochemical characterization in acidic medium of the graphitised CMK-3 showed that such a thermal treatment is effective to decrease the carbon oxidation rate (corrosion) while preserving a good porosity in terms of capacitance. Besides, the graphitisation degree and, in consequence the electrochemical corrosion resistance, can be modulated by an appropriate choice of thermal treatment conditions, where the heating rate and temperature appear as critical parameters. Under certain graphitisation conditions, the carbon corrosion of CMK-3 can be minimized showing lower rates compared to a commercial carbon black (Vulcan XC-72R). Palladium nanoparticles were supported on the most promising graphitised CMK-3 and Vulcan using a method based on impregnation and reduction with borohydride, resulting in suitable metal crystallite sizes. The electrocatalytic activity towards the oxidation of carbon monoxide and formic acid were assessed in aqueous sulphuric acid electrolyte for application at the anode of direct formic acid fuel cells (DFAFCs). The best activity results were obtained for the Pd catalyst supported on a graphitised CMK-3., The authors want to thank the Spanish Ministry of Economy and Competitiveness and FEDER for financial support under the project ENE2014-52158-C2-1-R. V. Celorrio also acknowledges the Royal Society and the UK National Academy by the support through the Newton International Fellows program.

5 figures, 3 tables.-- Supplementary material.-- © 2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/, In this work, Pd–Ni catalysts supported on carbon nanofibers were synthesized, with metal contents and Pd:Ni atomic ratios close to 25 wt.% and 1:2, respectively. Previously, the carbon nanofibers were chemically treated, in order to create surface oxygen and/or nitrogen groups. The synthesized catalysts displayed low crystallinity degree and high dispersion on carbon supports, especially in those with surface functional groups. Oxygen reduction reaction (ORR) was studied by rotating ring-disk electrode (RRDE) techniques. When the kinetic current is normalized by the mass of Pd present in the electrode, higher activities were obtained for the synthesized materials in comparison with the activity observed for a commercial Pd/C E-TEK catalyst. Some differences are reported for the different materials under study, mainly dependent on the presence of oxygen surface groups on the carbon support. In light of the results, we can propose the synthesized catalysts as possible candidates for cathodes in alkaline direct methanol fuel cells., The authors gratefully acknowledge financial support given by Spanish MINECO (ENE2014-52518-C2-1-R). UK Catalysis Hub is kindly thanked by VC and DJF for resources and support provided via our membership of the UK Catalysis Hub Consortium and funded by EPSRC (grants EP/K014706/1, EP/K014668/1, EP/K014854/1, EP/K014714/1 and EP/M013219/1).

10 figures, 4 tables, supplementary information.-- Work presented at the 5th Iberian Symposium on Hydrogen, Fuel Cells and Advanced Batteries (HYCELTEC 2015), 5-8 July 2015, Tenerife, Spain, Graphitized ordered mesoporous carbon CMK-3-R8 supported PtCrCo electrocatalysts were synthetized by the borohydride reduction method (BM) and then submitted to a reductive thermal treatment (TT) at 300, 500 and 700 °C with the aim to improve their catalytic activity toward the oxygen reduction reaction (ORR) and the methanol tolerance. Atomic composition and total metal loading were determined by energy dispersive X-ray (EDX) analysis and the values obtained were close to the nominal ones, i.e. 20 wt.% PtCrCO/CMK-3. Electrochemical measurements were carried out using rotating disk electrode (RDE) technique in oxygen-saturated sulfuric acid solution in absence and presence of dissolved methanol. Besides other species and parameters, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis revealed the formation of an ordered PtCr alloy phase and the surface enrichment by CrO species with the rise of the annealing temperature. The last, in conjunction with the absence of Pt sites with (110) orientation, enhances the catalytic activity toward the ORR and the methanol tolerance. Kinetic parameters are reported and analyzed in terms of the physicochemical properties of the catalysts obtained by the X-ray techniques., This research was funded by the Spanish Ministry of Economy and Competitiveness under projects CTQ2011-28913-C02 and ENE2014-52158-C2 (co-funded by FEDER). L.M. Rivera acknowledges the Canary Government (ACIISI) for its PhD scholarship. V.C. kindly thanks for resources and support provided via membership of the UK Catalysis Hub Consortium and funded by EPSRC (grants EP/K014706/1, EP/K014668/1, EP/K014854/1EP/K014714/1 and EP/M013219/1).

Pd nanoparticles have been supported onto different novel carbon materials to be used in the electroreduction of CO2 to high-added value products. Carbon nanocoils (CNCs), carbon nanofibers (CNFs) and ordered mesoporous carbon materials (OMCs) have been studied as support of the catalysts. In addition, Pd catalyst supported onto Vulcan XC-72R has been synthesized in order to establish a comparison with the commercial support. In this way, the influence of the carbon material on the physicochemical and electrochemical properties of the catalysts for the CO2 electroreduction process can be analyzed. Supports presented different morphologies and structures. CNFs and CNCs exhibited a crystalline structure with well-aligned graphitic layers and OMCs a hexagonal ordered structure composed of not crystalline carbon. Finally, Vulcan presented an intermediate structure between amorphous and graphitic. These differences do not affect significantly the average Pd crystallite size,although a different metal dispersion was found depending on the carbon material. On the other hand, cyclic voltammetry studies showed that CO2 was effectively reduced to other species at the surface of Pd/C catalysts. Additionally, it was proved that these species were adsorbed onto Pd at -1.0 V vs Ag/AgCl. Finally, a different catalytic activity towards the CO2 reduction reaction was observed for the different electrocatalysts, indicating an influence of the carbon support., The authors gratefully acknowledge financial support given by Spanish MINECO (CTQ2011‐28913‐C02‐01 and 02). S. Pérez-Rodríguez acknowledges Gobierno de Aragón for the DGA grant.

11 pag., 15 figures, 4 tables., Cordierite monolith-supported and powder Fe-K/Al2O3 catalysts were prepared and thoroughly characterized by bulk (XRD, Raman spectroscopy, XRF, ICP-OES, TPR) and surface (XPS, IR, N2-BET, NOx-TPD, K-TPD) sensitive methods. The catalytic activity was tested in TPO (temperature programmed oxidation) of model soot. The influence of the calcination temperature, i.e. 450 and 650°C, on the catalysts physicochemical properties and reactivity, type of surface states of K promoter and their role in the soot oxidation mechanism in the presence of NOx was evaluated. In the catalysts calcined at 450°C potassium was found to be mostly as free KNO3 whereas calcination at 650°C successfully transformed KNO3 into K2O, which during the soot oxidation yielded K2CO3 species. Such carbonates underwent decomposition in the presence of the oxygen surface groups of the support, leading to the formation of active basic O2- groups. NOx species were found to adsorb strongly on these O2- sites. The increased stability of thus formed NOx-species resulted in lower soot oxidation activity. In the same time, the catalysts calcined at 650°C evidenced higher ability towards the reduction of NOx, occurring simultaneously with the soot oxidation process. Additionally, the higher calcination temperature led to significantly higher stability of K promoter species as evidenced by potassium thermodesorption experiments. An overall schematic model of the catalyst morphology and relative distribution of the active components (K, Fe) over the Al2O3 support is proposed. © 2014 Elsevier B.V., Polish part would like to acknowledge the Polish National Science Center for funding awarded by the decision number DEC-2011/01/B/ST4/00574. On the Polish part the research was partially carried out with the equipment purchased thanks to the financial support of the European Regional Development Fund in the framework of the Polish Innovation Economy Operational Program (contract no. POIG.02.01.00-12- 023/08). S. Ascaso thanks CSIC for her JAE doctoral grant. S. Ascaso thanks CSIC for her JAE doctoral grant. M.E. Gálvez is indebted to the Spanish Ministry of Economy and Competitiveness (Secretaría de Estado de I+D+I, previously MICINN) for her Ramón y Cajal contract.

A novel differential electrochemical mass spectrometry (DEMS) cell has been developed to study gas diffusion electrodes (GDEs) used in fuel cells under operating conditions. In this way, catalytic and diffusion properties of the electrodes can be evaluated at the same time. Moreover, DEMS, allows the detection of volatile and gaseous products and intermediates generated in the electrochemical reactions with good sensitivity. In this way, CO2 conversion efficiencies are evaluated during alcohol oxidation reaction. In the present communication, the electrochemical behaviour towards hydrogen evolution and CO and alcohol electrooxidation at different platinum-based catalysts has been studied using the new DEMS cell configuration. The relative yields of CO2 and by-side products during methanol oxidation have been evaluated to determine the CO2 conversion efficiency. In addition, the diffusional properties of diverse GDEs have been considered., This work has been supported by the Gobierno de Aragón and Obra Social LaCaixa under project GA-LC-008/2009 and by the Gobierno de Canarias under project PI2007/023. S. Pérez-Rodríguez also acknowledges Gobierno de Aragón for their DGA grant. G. García acknowledges to the JAE program (CSIC) for financial support.

Vulcan XC-72R-supported Fe catalysts have been synthesised for the electroreduction of CO2 to high-added value products. Catalysts were obtained by the polyol method, using ethylene glycol as solvent and reducing agent. Prior to the metal deposition, Vulcan was subjected to different oxidation treatments in order to modify its surface chemistry and study its influence on the physicochemical and electrochemical properties of the catalysts, as well as on the product distribution. The oxidation treatments of the supportsmodify their textural properties, but do not affect significantly the physicochemical properties of catalysts. However, DEMS studies showed that the carbon support degradation, the distribution of products, and the catalytic activity toward the CO2 electroreduction reaction depend significantly on the surface chemistry of the carbon support., The authors gratefully acknowledge financial support given by MICINN (MAT2008-06631-C03-01 and 02) and Gobierno de Aragon and Obra Social La Caixa (GA-LC-008/2009). S. Perez-Rodrıguez acknowledges Gobierno de Aragon for the DGA grant. G. Garcıa acknowledges to the JAE program (CSIC) for financial support.

6 Figuras, La inquietud social creada por el cambio climático generado por las emisiones de gases con efecto invernadero, y en particular las de CO2, está forzando a todos los gobiernos, especialmente los más desarrollados, a la adopción de políticas energéticas que permitan la reducción progresiva de estas emisiones. En este escenario, se espera la progresiva implantación de la utilización del hidrógeno como vector energético para su aplicación en pilas de combustibles para automóviles y estaciones fijas de potencia de pequeño tamaño descentralizadas., Estos estudios se enmarcan dentro de variosproyectos de investigación del Plan Nacional de Energía, ENE2005-03801(MEC) y ENE2008-06516(MICINN), del Plan Nacional de Materiales, MAT2005-06669 (MEC) y MAT2008-06631(MICINN), de la Acción Estratégica de Nanociencia y Nanotecnología, NAN2004-09333-C05-01 (MEC), además del proyecto SPHERA que se engloba dentro del programa CENIT del CDTI (MICINN).

4 Figuras, 1 Tabla., [EN] Pd, PdCo and PdFe catalysts were prepared by the impregnation method, using sodium borohydride (NaBH4) as the reducing agent and a commercial carbon material (Vulcan XC-72R) as support. The synthesized electrocatalysts were tested for the formic acid oxidation reaction (FAOR) in acid medium (H2SO4 0.5 M). The morphology, composition and particle size of the electrocatalysts were characterized by physicochemical techniques as X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). The catalytic activity was evaluated by cyclic voltammetry (CV) and chronoamperometry techniques (CA)., [ES] Catalizadores de Pd, PdFe y PdCo fueron preparados por el método de impregnación, usando borohidruro de sodio (NaBH4) como agente reductor y un material de carbono comercial, (Vulcan XC-72R) como soporte. Los electrocatalizadores sintetizados fueron probados para la reacción de oxidación de ácido fórmico (FAOR, por sus siglas en inglés) en medio ácido (H2SO4 0,5 M). La morfología, la composición y el tamaño de partícula de los electrocatalizadores se caracterizaron mediante técnicas físico-químicas como difracción de rayos X (XRD), microscopía electrónica de barrido con espectroscopia por energía dispersiva (SEM-EDS) y microscopia electrónica de transmisión (TEM). La actividad catalítica se evaluó mediante técnicas de voltamperometría cíclica (CV) y cronoamperometría (CA)., LJM agradece a CONACyT por la beca otorgada para la realización de los estudios de Maestría, así como a UAM-A, ICB, IPN por el apoyo otorgado para la realización de este trabajo. MGMY, MRR, MEPP y AEM agradecen al SNI. MGMY agradece a L ́oreal-UNESCO-CONACyT-AMC por la beca en Mujeres en la Ciencia 2016. MJL and SPR agradecen al Gobierno de Aragón (DGA) y FEDER por la financiación a través del Grupo de Investigación Conversión de Combustibles (T06_17R)