Electrochemical growth of CoNi and Pt-CoNi soft magnetic composites on an alkanethiol monolayer-modified ITO substrate

CoNi and Pt-CoNi magnetic layers on indium-tin oxide (ITO) substrates modified by an alkanethiol self-assembled monolayer (SAM) have been electrochemically obtained as an initial stage to prepare semiconducting layer-SAM-magnetic layer hybrid structures. The best conditions to obtain the maximum compactness of adsorbed layers of dodecanethiol (C12-SH) on ITO substrate have been studied using contact angle, AFM, XPS and electrochemical tests. The electrochemical characterization (electrochemical probe or voltammetric response in blank solutions) is fundamental to ensure the maximum blocking of the substrate. Although the electrodeposition process on the SAM-modified ITO substrate is very slow if the blocking of the surface is significant, non-cracked metallic layers of CoNi, with or without a previously electrodeposited seed-layer of platinum, have been obtained by optimizing the deposition potentials. Initial nucleation is expected to take place at the pinhole defects of the C12-SH SAM, followed by a mushroom-like growth regime through the SAM interface that allows the formation of a continuous metallic layer electrically connected to the ITO surface. Due to the potential of the methodology, the preparation of patterned metallic deposits on ITO substrate using SAMs with different coverage as templates is feasible

Electrochemical synthesis of Co7Ni3 and Co6Ni4 nanorods with controlled crystalline phase. Application to methanol electro-oxidation

CoNi nanorods with modulated crystalline phase have been synthesised by means of a potentiostatic deposition method, using a single electrolytic bath, by only varying the electrodeposition potential. The growth of the nanorods in the interior on the nanochannels of the membrane is mainly controlled by the limited transport of the Co(II) and Ni(II) ions to the growth front. Two types of CoNi nanorods of several microns long, with similar composition but different crystalline phases depending on the applied potential, have been obtained. The potentials for the electrosynthesis of the nanorods have been selected to induce different deposition rates and, as a consequence, different crystalline phases, hcp for the lower deposition rates and fcc (+hcp) for the highest ones. For each selected potential, the nanorods present the same composition and crystalline phase along the rods. The test of the two types of nanorods for the methanol electro-oxidation demonstrated both the specific electrocatalytic behaviour of each one and the promising behaviour of the nanorods as electrocatalysts in direct methanol fuel cells in basic medium, due to their higher surface/volume ratio than that of thin films and the superior stability than that of nanoparticles. The influence of the crystalline phase in the methanol electro-oxidation has been also corroborated from pure-hcp and pure-fcc CoNi films

High spatial resolution optical imaging of the multiple T Tauri system LkH{\alpha} 262/LkH{\alpha} 263

We report high spatial resolution i' band imaging of the multiple T Tauri system LkH$\alpha$ 262/LkH$\alpha$ 263 obtained during the first commissioning period of the Adaptive Optics Lucky Imager (AOLI) at the 4.2 m William Herschel Telescope, using its Lucky Imaging mode. AOLI images have provided photometry for each of the two components LkH$\alpha$ 263 A and B (0.41 arcsec separation) and marginal evidence for an unresolved binary or a disc in LkH$\alpha$ 262. The AOLI data combined with previously available and newly obtained optical and infrared imaging show that the three components of LkH$\alpha$ 263 are co-moving, that there is orbital motion in the AB pair, and, remarkably, that LkH$\alpha$ 262-263 is a common proper motion system with less than 1 mas/yr relative motion. We argue that this is a likely five-component gravitationally bounded system. According to BT-settl models the mass of each of the five components is close to 0.4 M$_{\odot}$ and the age is in the range 1-2 Myr. The presence of discs in some of the components offers an interesting opportunity to investigate the formation and evolution of discs in the early stages of multiple very low-mass systems. In particular, we provide tentative evidence that the disc in 263C could be coplanar with the orbit of 263AB.Comment: 11 pages, 7 figures, Accepted 2016 May

La subnutrición preparto y el hidroxitirosol en el equilibrio pro- y anti-oxidante de la sangre durante la etapa de lactación

La suplementación materna con HT mejoró la respuesta antioxidante de los terneros de vacas subnutridas. La capacidad antioxidante en vacas y el MDA en vacas y terneros incrementaron al avanzar la gestación.: Proyecto financiado por MCIN/AEI/ 10.13039/501100011033 (FETALNUT). Contrato predoctoral de la Universitat de Lleida N. Escalera-Moreno. Los autores agradecen a M. Joy y a J.R. Bertolín (CITA-IA2(UNIZAR)) la ayuda proporcionada en el análisis de las muestras

Efecto de la subnutrición preparto y el hidroxitirosol en el equilibrio pro- y anti-oxidante de la sangre durante el último tercio de gestación

La subnutrición durante el último tercio de gestación en vacas disminuyó la capacidad total antioxidante y aumentó la peroxidación lipídica en el último tercio de la gestación. La suplementación con HT redujo el daño oxidativo en las vacas subnutridas.: Proyecto financiado por MCIN/AEI/ 10.13039/501100011033 (FETALNUT). Contrato predoctoral de la Universitat de Lleida N. Escalera-Moreno. Se agradece a M. Joy y a J.R. Bertolín (CI -TA-IA2-(Unizar)) la ayuda proporcionada en el análisis de las muestras

Recent advances in unveiling active sites in molybdenum sulfide-based electrocatalysts for the hydrogen evolution reaction

Hydrogen has received significant attention as a promising future energy carrier due to its high energy density and environmentally friendly nature. In particular, the electrocatalytic generation of hydrogen fuel is highly desirable to replace current fossil fuel-dependent hydrogen production methods. However, to achieve widespread implementation of electrocatalytic hydrogen production technology, the development of highly active and durable electrocatalysts based on Earth-abundant elements is of prime importance. In this context, nanostructured molybdenum sulfides (MoS x ) have received a great deal of attention as promising alternatives to precious metal-based catalysts. In this focus review, we summarize recent efforts towards identification of the active sites in MoS x -based electrocatalysts for the hydrogen evolution reaction (HER). We also discuss recent synthetic strategies for the engineering of catalyst structures to achieve high active site densities. Finally, we suggest ongoing and future research challenges in the design of advanced MoS x -based HER electrocatalysts

Electrochemical growth of CoNi and Pt-CoNi soft magnetic composites on an alkanethiol monolayer-modified ITO substrate

CoNi and Pt-CoNi magnetic layers on indium-tin oxide (ITO) substrates modified by an alkanethiol self-assembled monolayer (SAM) have been electrochemically obtained as an initial stage to prepare semiconducting layer-SAM-magnetic layer hybrid structures. The best conditions to obtain the maximum compactness of adsorbed layers of dodecanethiol (C12-SH) on ITO substrate have been studied using contact angle, AFM, XPS and electrochemical tests. The electrochemical characterization (electrochemical probe or voltammetric response in blank solutions) is fundamental to ensure the maximum blocking of the substrate. Although the electrodeposition process on the SAM-modified ITO substrate is very slow if the blocking of the surface is significant, non-cracked metallic layers of CoNi, with or without a previously electrodeposited seed-layer of platinum, have been obtained by optimizing the deposition potentials. Initial nucleation is expected to take place at the pinhole defects of the C12-SH SAM, followed by a mushroom-like growth regime through the SAM interface that allows the formation of a continuous metallic layer electrically connected to the ITO surface. Due to the potential of the methodology, the preparation of patterned metallic deposits on ITO substrate using SAMs with different coverage as templates is feasible

Electrochemically decorated iridium electrodes with WS₃₋_x toward improved oxygen evolution electrocatalyst stability in acidic electrolytes

Iridium-based oxides, currently the state-of-the-art oxygen evolution reaction (OER) electrocatalysts in acidic electrolytes, are cost-intensive materials which undergo significant corrosion under long-term OER operation. Thus, numerous researchers have devoted their efforts to mitigate iridium corrosion by decoration with corrosion-resistant metal oxides and/or supports to maximize OER catalyst durability whilst retaining high activity. Herein a one-step, facile electrochemical route to obtain improved IrOx thin film OER stability in acid by decorating with amorphous tungsten sulphide (WS3−x) upon electrochemical decomposition of a [WS4]2− aqueous precursor is proposed. The rationale behind applying such WS3−x decoration stems from the generation of a tungsten oxide phase, a well-known corrosion-resistant photoactive OER catalyst. The study demonstrates the viability of the proposed WS3−x decoration, allowing the tailoring of experimental parameters responsible for WS3−x nanoparticle size and surface coverage. OER stability tests coupled by ex situ SEM and XPS corroborate the beneficial effect of WS3−x decoration, yielding improved OER specific activity metrics along with minimized Ir surface roughening, a characteristic of electrodissolution. Iridium decoration with electrodeposited, corrosion-resistant oxides is consequently shown to be a promising route to maximize OER stabilities

Influencia del grado de refuerzo y de la composición de la matriz en la resistencia a la corrosión de materiales compuestos de matriz de aluminio (A3xx.x/SiC) en 80% humedad relativa (HR)

A study of the influence of the SiCp proportion of four aluminium metal composites (A380/SiC/10p, A380/SiC/20p, A360/SiC/10p y A360/ SiC/20p) on 80%HR at 25 and 50ºC, simulated under climatic chamber. The matrix of A360/SiC/xxp composites is virtually free of Cu while the A380/SiC/xxp matrix contains 1.39-1.44wt%Ni and 3.13-3.45wt%Cu. The kinetics of the corrosion process were studied on the basis of gravimetric tests. The nature of corrosion products was studied as a function of the reinforcement proportion, matrix concentration and test conditions. At the humidity environment tested, both the material corrosion resistance and the stability of the passive layer were high. The damage was low and increased with temperature, SiCp proportion and Cu matrix composition.<br><br>Se estudia la influencia de la proporción de SiC en la resistencia a la corrosión de los materiales compuestos de matriz de aluminio A380/ SiC/10p, A380/SiC/20p, A360/SiC/10p y A360/SiC/20p, cuando operan en un ambiente con 80% HR a 25º y 50ºC, que ha sido simulado mediante cámara climática. La matriz del material A360/SiC/xxp no contiene Cu, mientras que el material A380/SiC/xxp contiene entre el 1,39-1,44% de Ni y 3,13-3,45 de Cu. Se ha llevado a cabo un estudio cinético mediante medidas gravimétricas. Se ha estudiado la naturaleza de los productos de corrosión en función de la proporción de refuerzo, de la composición de la matriz y de las condiciones de exposición al medio agresivo. Para la humedad ensayada, la resistencia a la corrosión de estos materiales es elevada y el grado de protección de la capa pasiva es alto. El grado de daño, aunque es pequeño aumenta con la temperatura y es función tanto de la composición de la matriz como del porcentaje de refuerzo

Electrochemical synthesis of Co7Ni3 and Co6Ni4 nanorods with controlled crystalline phase. Application to methanol electro-oxidation

CoNi nanorods with modulated crystalline phase have been synthesised by means of a potentiostatic deposition method, using a single electrolytic bath, by only varying the electrodeposition potential. The growth of the nanorods in the interior on the nanochannels of the membrane is mainly controlled by the limited transport of the Co(II) and Ni(II) ions to the growth front. Two types of CoNi nanorods of several microns long, with similar composition but different crystalline phases depending on the applied potential, have been obtained. The potentials for the electrosynthesis of the nanorods have been selected to induce different deposition rates and, as a consequence, different crystalline phases, hcp for the lower deposition rates and fcc (+hcp) for the highest ones. For each selected potential, the nanorods present the same composition and crystalline phase along the rods. The test of the two types of nanorods for the methanol electro-oxidation demonstrated both the specific electrocatalytic behaviour of each one and the promising behaviour of the nanorods as electrocatalysts in direct methanol fuel cells in basic medium, due to their higher surface/volume ratio than that of thin films and the superior stability than that of nanoparticles. The influence of the crystalline phase in the methanol electro-oxidation has been also corroborated from pure-hcp and pure-fcc CoNi films