(Consejo Superior de Investigaciones Científicas – Universidad de Sevilla)


next talk:
April 21st (Tuesday) | 10.00 h 
Seminario CicCartuja2 

Correction to comprehensive experimental and theoretical study of the CO+NO reaction catalyzed by Au/Ni nanoparticles

Dr.  Juan Pedro Holgado Vázquez

+ info

The catalytic and structural properties of five different nanoparticle catalysts with varying Au/Ni composition were studied by six different methods, including in situ X-ray absorption spectroscopy and density functional theory (DFT) calculations. The as-prepared materials contained substantial amounts of residual capping agent arising from the commonly used synthetic procedure. Thorough removal of this material by oxidation was essential for the acquisition of valid catalytic data. All catalysts were highly selective toward N2 formation, with 50–50 Au:Ni material being best of all. In situ X-ray absorption near edge structure spectroscopy showed that although Au acted to moderate the oxidation state of Ni, there was no clear correlation between catalytic activity and nickel oxidation state. However, in situ extended X-ray absorption fine structure spectroscopy showed a good correlation between Au–Ni coordination number (highest for Ni50Au50) and catalytic activity. Importantly, these measurements also demonstrated substantial and reversible Au/Ni intermixing as a function of temperature between 550 °C (reaction temperature) and 150 °C, underlining the importance of in situ methods to the correct interpretation of reaction data. DFT calculations on smooth, stepped, monometallic and bimetallic surfaces showed that N + N recombination rather than NO dissociation was always rate-determining and that the activation barrier to recombination reaction decreased with increased Au content, thus accounting for the experimental observations. Across the entire composition range, the oxidation state of Ni did not correlate with activity, in disagreement with earlier work, and theory showed that NiO itself should be catalytically inert. Au–Ni interactions were of paramount importance in promoting N + N recombination, the rate-limiting step.

ICMS-sci-talks are held by scientists from the Materials Science Institute of Seville with the aim of discussing and disseminating their research activity. They consist of 20-25 min talks focussed on a recently published paper.
These talks take place about every three weeks at 10.00 am in the seminar room at cicCartuja2 (yellow building).

Nanomaterials at the frontline of the energy challenge

Prof. Valeria Nicolosi

Trinity College Dublin, School of Chemistry, CRANN, AMBER and IForm Centres, Dublin 2, Ireland


September 14 (Thursday) | 11.00 h


Liquid phase exfoliation has been proved to be a cheap, scalable method for the mass production of 2D sheets. This talk will first discuss the galaxy of existent layered materials, with emphasis on synthesis, liquid-phase exfoliation, and characterization, focusing on some key applications recently developed in our laboratories, ranging from energy storage to printed electronics. We will for example discuss how two-dimensional nanomaterials can be formulated in aqueous and organic viscous inks for extrusion printing, inkjet printing, and aerosol jet 3D printing, and demonstrate direct printing on various substrates. The additive- and binary solvent-free inks do not show coffee ring effect, enabling high-resolution printing without substrate pre-treatment. The resulting printed micro-supercapacitors showcase excellent charge storage performance, including areal capacitance up to 100 mF/cm2 and volumetric capacitance up to 800 F/cm3 in protic gel electrolyte, coupled with long lifetime and good flexibility. The versatile direct-ink-printing technique highlights the promise of 2D nanomaterials functional inks for scalable fabrication of easy-to-integrate components of printable electronics. In this talk we will also demonstrate how such inks can be used to develop novel nanomaterials-based battery solutions.Increasing the energy storage capability of batteries necessitates maximization of their areal capacity. This requires thick electrodes performing at near-theoretical specific capacity. However, achievable electrode thicknesses are restricted by mechanical instabilities, with high-thickness performance limited by the attainable electrode conductivity. Here we show that forming a segregated network composite of carbon nanotubes with a range of lithium storage materials (for example, silicon, graphite, and metal oxide particles) suppresses mechanical instabilities by toughening the composite, allowing the fabrication of high-performance electrodes with thicknesses of up to 800 μm. Such composite electrodes display conductivities up to 1 × 104 S m−1 and low charge-transfer resistances, allowing fast charge-delivery and enabling near-theoretical specific capacities, even for thick electrodes. The combination of high thickness and specific capacity leads to areal capacities of up to 45 and 30 mAh cm−2 for anodes and cathodes, respectively. Combining optimized composite anodes and cathodes yields full cells with state-of-the-art areal capacities (29 mAh cm−2) and specific/volumetric energies (480 Wh kg−1 and 1,600 Wh l−1)..

Figure 1: Printed devices based on MXenes inks

+ info

The invited conferences are held by researchers form groups in topics of utmost interest to our Institute. With the conferences, we intend to favour the stablishment of conctacts between the invited researchers and our research groups.
The invited seminars are held montly on Thursday mornings,  in the Seminars room at cic-cartuja 2 (yellow building).

Seminario cicCartuja2 / Salón de Grados cicCartuja2

Seminario cicCartuja2 / Salón de Grados cicCartuja2

Seminario cicCartuja 2

ICMS Invited Lectures
Salón de Grados cicCartuja 2

Centro de Investigaciones Científicas “Isla de la Cartuja”
Americo Vespucio, 49
Isla de la Cartuja Sevilla
41092 España
Teléfono: 954489500