A collaborative effort of the teams from Universities in Aarhus, Geneva and Louvain-la-Neuve (Yaroslav Filinchuk of IMCN Institute), as well as from the Helmholtz Center in Geesthacht, has lead to a comprehensive review of 70 pages in the prestigious journal "Chemical Society Reviews", covering the chemistry of borohydrides. These compounds are seen as perspective hydrogen stores for energy applications, and more recently they appear as multifunctional materials with remarkable properties of ionic conductivity, gas adsorption, CO2 recycling etc. Despite this class of compounds was first seen as simple ionic salts, complex coordination chemistry was revealed for the borohydride anion, paving a way to rational design of new functional materials. DOI: 10.1039/c6cs00705h
Dr. Ronggang CAI has been granted the PhD Award in the field of Material Science for his work entitled “Nanoimprinted ferroelectric polymer layers for organic memory devices and multiferroism “ by the Royal Belgian Society of Microscopy (RBSM vzw).
The RBSM awards up to three prizes annually to members who have successfully defended their PhD thesis on a microscopy-related subject in Belgium in one of the following three areas: Life Sciences, Physics and Material Sciences and Instrumentation and Methods. Theses are judged on their contribution to the advancement of microscopy in Belgium. This include the development of new methods or instrumentation, application of existing methods in new fields of research, use of techniques new to Belgium, or the demonstration of the power of microscopy by extensive use of microscopy data. The term microscopy is used in a broad sense, including all techniques providing information with a spatial resolution better than the naked human eye, and supporting techniques such as image analysis.
In the frame of her PhD thesis, Josefine Schnee (IMCN Institute / pole MOST), team of Eric Gaigneaux, and teaching assistant at the faculty of bioscience engineering) demonstrated for the first time that hexagonal boron nitride (BN) is an excellent support for H3PW12O40 Keggin units (KU) used as catalysts for the gas phase 100% selective methanol-to-dimethylether (DME) reaction at 150°C. Only mildly interacting with the KU, BN preserves their strong acidity, and leads to catalysts outcompeting by a factor 10 the KU supported on the most commonly used TiO2. KU on BN perform even better than adequately activated pure bulk KU crystals which were the most efficient catalysts to date thanks to their pseudo-liquid behavior. This effect is due to the ability of BN to stabilize still small enough KU crystallites. The dehydration of methanol to DME currently attracts much attention as the latter is indeed one of the most promising alternative fuels for the future. Indeed DME has a particularly low climate impact, being biodegradable, noncorrosive, and nontoxic and burning without emission of particulates or nitrous oxides.
Reprinted with permission from ACS Catalysis, 2017, 7, pp 4011–4017. DOI: 10.1021/acscatal.7b00808. Copyright (2017) American Chemical Society
Due to its superacidity and ability of its bulk to react following a pseudoliquid mechanism, the Keggin H3PW12O40 heteropolyacid attracts more and more attention as a catalyst for the gas phase methanol-to-DME reaction. However, in its pure state, H3PW12O40 has a very low surface area (typically 5−10 m2/g), which limits the accessibility of its inner protons due to diffusional constraints and explains why teams investigate H3PW12O40 in its supported form. In this work, it is highlighted the interest of using hexagonal boron nitride (BN) as a support. It is shown that, in contrast to commonly used supports such as TiO2, BN is able to increase the accessibility of H3PW12O40’s acid sites (i.e., stabilizing small enough crystallites) while preserving their strong acidity (i.e., not interacting too much with the Keggin units). At low loadings (typically around 16% of one ideal Keggin monolayer), BN leads H3PW12O40 to reach an almost 2 times higher methanol conversion than obtained with the adequately activated pure bulk sample, and an almost 10 times higher conversion than an optimized TiO2-supported H3PW12O40 catalyst. At higher H3PW12O40 loadings, the BN-supported catalysts are still much more active than the optimized TiO2-supported one, but less active than the pure bulk-activated H3PW12O40, which was attributed to the partial intercalation of H3PW12O40 within the interlayers of BN.
Reproduced with permission from ACS Catalysis, 2017, 7, pp 4011–4017. DOI: 10.1021/acscatal.7b00808. Copyright (2017) American Chemical Society
More on the work of Josefine Schnee and Eric Gaigneaux on catalytic behavior of Keggin H3PW12O40 heteropolyacid in the methanol-to-DME dehydration, via in situ and operando spectroscopy, can be found in :
Applied Catalysis A, 538 (2017) 174-180; Catalysis Science & Technology, 7 (2017) 817-830; Journal of Physical Chemistry C, 121 (2017) 556–566; Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 173 (2017) 151-159.
Ronggang CAI has received the 2017 IMCN Best thesis Award on 24 May 2017.
His work was entitled "Nanoimprinted Ferroelectric Polymer Layesr for Organic Memory devices and Multiferroism".
This Prize, which is granted yearly by the IMCN Institute, rewards the most outstanding PhD work among those who graduated during the previous civil year (2016 in the present case). A selection Committee chaired by Prof. Jacques DEVAUX and composed of one member per pole and the VPR noticed the high quantity and quality of research carried out by Ronggang, as well as his communication skills at various levels (conferences, publications, PhD defense). This initiative aims at promoting excellence in scientific research within the Institute.
Organic electronics has proven to be a promising technology for large-area electronic applications, such as foldable displays and electronic papers. To realize their functionalities, most of these applications need memory components to store information. For this purpose, memory devices based on organic ferroelectric polymers, e.g., P(VDF-TrFE), have been developed over the last decades and considered as excellent candidates.
In these devices, information (bits 1 and 0) is stored as two polarization states of the ferroelectric polymer. Therefore, the memory devices should be designed so that two stable polarization states can be easily obtained, with an easy read-out of the information which preferably does not alter the polarization states.
This requires smart designs of device structures, proper usages of materials and processing conditions, and a fine understanding of the switching mechanisms of the ferroelectric polymer.
Since all these requirements are related to each other, the main objective of this thesis is to identify links between the main parameters, and to find optimized conditions to fabricate and characterize memory devices. To achieve this objective, the following work was conducted in this thesis: (i) a study of the switching mechanism of the ferroelectric polymer in ferroelectric field-effect transistors; (ii) an improvement of the memory performance by optimizing the processing conditions; (iii) the design of new device structures or materials which could be used for memory applications. Two new systems are investigated: the first one is a transistor-like device consisting of a hybrid layer with alternating ferroelectric/semiconductor nanowires and the second one is a nanopatterned multiferroic layer made of ferroelectric polymer and ferromagnetic metal. The switching mechanisms and the potential usages for memory applications of these two systems are demonstrated.
Dr Camila Fernandez has received the € 10,000 Umicore Materials Technology Award for her PhD work in the field of exploring dynamic catalytic processes for synthesizing ammonia on ruthenium-supported nanoparticles at low temperatures.
Dr Fernandez’s entry was one of 15 submitted from all over Europe. Camila Fernandez made her PhD studies under the supervision of Professors Eric Gaigneaux and Patricio Ruiz.
Multiferroic Nanopatterned Hybrid Material with Room-Temperature Magnetic Switching of the Electric Polarization
A multidisciplinary team from BSMA (groups of Alain Jonas, Bernard Nysten and Luc Piraux, with principal researchers Ronggang Cai and Vlad Antohe), in collaboration with Zhijun Hu from Soochow University (China) – a former post-doc from BSMA, fabricated a composite multiferroic layer wherein electrical information can be stored by a magnetic field. The layer offers new opportunities for data storage and remote actuation. Published in Advanced Materials
In magnetoelectric materials, it is theoretically possible to write electrically-stored information by a magnetic field, or magnetically-stored information by an electric field. This opens interesting opportunities for designing new memory architectures or sensors. However, the coupling of ferromagnetism and ferroelectricity is most often weak in magnetoelectric materials, and writing magnetically an electrical information has been so far limited to low temperatures, or relatively complex inorganic materials.
Now, a multidisciplinary team from IMCN (Bio & Soft Matter) reports in Advanced Materials (http://dx.doi.org/10.1002/adma.201604604) on a regularly-nanopatterned layer made of a continuous ferroelectric plastic with embedded ferromagnetic metallic nanopillars. In this layer, the orientation of the electric polarization of the polymer can be flipped by applying a magnetic field in the presence of an aiding electric field. This happens at room temperature, and is mediated by internal stresses in the polymer building upon applying the magnetic field.
Not only is the room-temperature operation of this material of interest; its ease of fabrication, which involves relatively simple molding and electrodeposition operations, and the resulting regularly nanopatterned structure of the layer, are both attractive for practical applications. This being said, further research will be needed to fully understand the complex role of internal stresses in the magnetoelectric effect of the composite layer. Also intriguing is the relaxation of the material resulting from the motion of segments of the polymer chains under the action of electric and magnetic fields. But beyond this complexity, the study shows that new properties and coupling effects may arise when properly controlling the arrangement of well-known materials into composite nanostructures.
The thermodynamic scale of inorganic crystalline metastability
Geoffroy Hautier, in collaboration with colleagues from MIT, Berkeley National Laboratory, University of California Berkeley and University of California San Diego, have reported in Science Advances on a new thermodynamic understanding of metastability in materials (DOI: 10.1126/sciadv.1600225 link to http://advances.sciencemag.org/content/2/11/e1600225)
The ability to form metastable materials (i.e. materials not thermodynamically stable in their operating conditions) is essential to many applications from next-generation electronics to new steels. The rationalization and understanding of their formation in a general framework has been relatively unexplored. The researchers provide here a novel insight into the thermodynamic factors affecting metastability. Using the Materials Project (http://www.materialsproject.org), a database containing ab initio computed energies for around 30,000 inorganic compounds, they have performed an extensive thermodynamic and statistical analysis. They have quantified a scale of acceptable instability to form metastable compounds and discovered the chemical factors influencing metastability. Their work support the hypothesis that most metastable inorganic compounds form by “remanent metastability” and offer a guideline to the prediction of materials synthesizability: “synthesis of novel metastable crystalline phases should target conditions where they are thermodynamically stable, and aim to kinetically retain them to conditions where metastable. If conditions of thermodynamic stability cannot be found, realization of these predicted metastable phases may not be possible”. The work is accessible with open access in Science Advances (link http://advances.sciencemag.org/content/2/11/e1600225)
Prof. Evelyne VAN RUYMBEKE obtained an Arthur B. Metzner Early Career Award. A most important award in the field of Rheology.
My overall objective is to understand how to relate the molecular structure of soft materials to their dynamics and viscoelastic properties, towards the design of novel materials with desired properties. To this end, we investigate the rheological behavior of different polymeric systems and starting from these experimental results, we develop molecular models based on the tube theory, which are able to describe, at the mesoscopic length-scale, the motion and relaxation of the chains. For sample with unknown composition, this also requires developing statistical tools in order to relate their synthesis to their most probable composition (in term of chain architectures).
Today, my main research interests focus on understanding the dynamics of architecturally complex macromolecules as well as of supramolecular polymeric assemblies, this last topic being the objective of the European ITN that I am coordinating (www.supolen.eu).
Prof. Evelyne Van Ruymbeke
In the tube model, the chains entanglements, which prevent a specific chain to freely explore its surrounding,
are represented by a virtual tube in which the chain is confined.
Professeur de Recherche Francqui
Jean-Christophe Charlier has obtained the Francqui Research Fellowship, which will allow him to concentrate fully on his research on properties of two-dimensional materials.
This prestigious position, attributed by the Francqui Foundation, allows its beneficiary to diminish his teaching load for a three-year period, in the present case from September 2016 until September 2019. This mandate will allow Jean-Christophe to pursue his high level research on bi-dimensional materials. Partner in the ‘Graphene Flagship’ consortium of the European Union, Jean-Christophe Charlier develops ab initio methods to predict the structural, electronic and optical properties of these materials. Beyond graphene, which is the famous bidimensional all-carbon network, other lamellar materials are now being investigated in close collaboration with experimentalists from MIT, Cambridge or Stanford. More information can be found at http://www.uclouvain.be/770893.html
Molecular Engineering of Trifunctional Supported Catalysts for the Aerobic Oxidation of Alcohols
IMCN researchers (Dr. Antony E. Fernandes, Prof. Olivier Riant and Prof. Alain M. Jonas), in collaboration with Prof. Klavs F. Jensen (MIT, Dept. of Chem. Eng., U.S.A.), have developed a general and simple strategy for the precision preparation of multifunctional supported catalysts, reported in Angewandte Chemie (DOI: 10.1002/anie.201603673).
A general method for the precision preparation and molecular engineering of multifunctional supported catalyst
Multifunctional supported catalysts are central in the development of modern and sustainable chemistry that most often requires an orchestrated combination of a set of catalytic components, in a way similar to enzymes in our body that operate by structuring active amino acid residues into a tailored catalytic pocket. However, it is generally difficult to prepare this type of catalysts with high molecular-level precision and minimum synthetic efforts because of the wide chemical diversity of active sites that have to be brought together.
In this context, the researchers at UCL and MIT reported a general, simple and modular method for the simultaneous immobilization of multiple catalytically-active functions on mesoporous silica that allows precise control of surface composition and cooperative interactions between individual sites. This approach enables the development of heterogeneous catalysts with activity superior to their homogeneous equivalents as a result of engineered synergistic effects.
The method described in Angewandte Chemie (DOI: 10.1002/anie.201603673) provides a powerful tool for the rational and rapid development of multifunctional supported catalysts that could open new avenues in heterogeneous catalysis.
Jérémy BRASSINE has received the 2016 IMCN Best thesis Award on May 20, 2016.
His work was entitled "Utilization of metallo-supramolecular interactions to control the structure, self-organization and dynamic of stimuli-responsive polymeric systems".
This Prize, which is granted yearly by the IMCN Institute, rewards the most outstanding PhD work among those who graduated during the previous civil year (2015 in the present case). A
selection Committee chaired by Prof. Patrick Bertrand and composed of one member per pole and the VPR noticed the high quantity and quality of research carried out by Jérémy, as well as his communication skills at various levels (conferences, publications, PhD defense). This initiative aims at promoting excellence in scientific research within the Institute.
This interdisciplinary PhD thesis arose in the context of challenging technological developments, namely smart and healable materials. In this research, the combination of metal–ligand interactions with classical macromolecular architectures has proved to be a straightforward approach towards supramolecular multi-responsive hydrogels thanks to the hierarchical organization of ligand-functionalized block copolymers obtained via controlled polymerization techniques. Depending on the characteristics of these molecular building blocks, the intermolecular forces involved in the multiple assembly processes were fine-tuned in order to control the rheology of the materials.
The fundamental relationships between material structure, dynamics and mechanics were established through a comprehensive characterization of their rich rheological behavior. In addition, both structure and dynamics were capable of adjustments in response to a wide variety of stimuli including temperature, chemical environment, and mechanical stress. By defining an original strategy for designing novel materials and exploring their potential, this thesis has thus offered exciting new opportunities toward stimuli-responsive structures exhibiting tunable properties. The research project has been carried out under the supervision of Profs. C.-A. Fustin and J.-F. Gohy within the BSMA pole of our Institute.