April 21st (Tuesday) | 10.00 h
Correction to comprehensive experimental and theoretical study of the CO+NO reaction catalyzed by Au/Ni nanoparticles
Dr. Juan Pedro Holgado Vázquez
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).
September 26th (Monday) | 11.00 h
Salón de Grados CicCartuja2
Small scale high performance photonic devices for biomedical, agricultural, and environmental applications
Department of Electro-Optics and Photonics Engineering and The Ilse Katz Institute for Nanoscale Science and Technology, ECE School, Ben Gurion University, Israel
Developments in nanotechnology, electronics, computing, algorithms, imaging, and fabrication technologies are assisting us in miniaturizing optical/photonic devices to become portable and suitable for point of care and field applications. During the last 10 years we have been working on different technologies for this purpose including full field optical coherence tomography, plasmonic sensors, and spectral/polarization control liquid crystal devices.
In this lecture I will review our miniaturized devices developed for these purposes including spectro-polarimetric imaging module based on unique liquid crystal devices demonstrated for skin cancer detection, plasmonic sensor with less than 1kg weight and small form factor demonstrated for detecting biomarkers, viruses, bacteria and other analytes, SERS sensors with ultrahigh enhancement, and more.
- Lior Graham, Yitzhak Yitzhaky and I. Abdulhalim, Classification of skin moles from optical spectro-polarimetric images, J. Biomed. Optics 18, 111403 (2013).
- Sachin K. Srivastava, Atef Shalabney, I. Khalailah, Christoph Grüner, B. Rauschenbach, and I. Abdulhalim, SERS Biosensor using Metallic nanoSculptured Thin Films for the Detection of Endocrine Disrupting Compound Biomarker Vitellogenin, Small 10, 3579-3587 (2014).
- Avner Safrani and Ibrahim Abdulhalim, High speed 3D imaging using two wavelengths parallel phase shift interferometry, Optics Letters 40, 4651-4 (2015).
- Michael Ney and I. Abdulhalim, Ultrahigh polarimetric image contrast enhancement for skin cancer diagnosis using InN plasmonic nanoparticles in the THz range, J. Biomed. Optics 20, 125007(14p) (2015).
- Sachin K. Srivastava, Christoph Gruner, Dietmar Hirsch, Bernd Rauschenbach, Ibrahim Abdulhalim, Enhanced intrinsic fluorescence from carboxidized nano-sculptured thin films of silver and their application for label free dual detection of glycated hemoglobin, Optics Express 25, 4761-72 (2017).
- Andrey Nazarov, Boris Knyazer, Tova Lifshitz, Mark Schvartzman, Ibrahim Abdulhalim, Assessment of intraocular pressure sensing using an implanted reflective flexible membrane, J. Biomed. Opt., 22(4), 047001 (2017).
- Marwan J. Abuleil and Ibrahim Abdulhalim, Broadband ellipso-polarimetric camera utilizing tunable liquid crystal achromatic waveplate with improved field of view, Optics Express 27 (9) 12011-24 (2019).
- Dorin Harpaz, Brescia Koh, Robert S. Marks, Raymond C. S. Seet, Ibrahim Abdulhalim and Alfred I. Y. Tok, Point-of-Care Surface Plasmon Resonance Biosensor for Stroke Biomarkers NT-proBNP and S100β using a Functionalized Gold Chip with Specific Antibody, Sensors, 19, 2533(16p) (2019).
- Aabha Bajaj, Anand M. Shrivastav, Evgeny Eltzov, Noam Alkan, and Ibrahim Abdulhalim, Detection of necrotrophic DNA marker of anthracnose causing Colletotrichum gloeosporioides fungi in harvested produce using surface plasmon resonance, Talanta 235, 122776 (2021).