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Université de Fribourg

Covalent triazine frameworks incorporating charged polypyrrole channels for high-performance lithium–sulfur batteries

Kim, Jiheon ; Elabd, Ahmed ; Chung, Sung-Yoon ; Coskun, Ali ; Choi, Jang Wook

In: Chemistry of Materials, 2020, vol. 32, no. 10, p. 4185–4193

Organosulfur polymers have emerged as promising electrode materials for lithium– sulfur (Li–S) batteries, mainly because of their ability to incorporate and stabilize high sulfur content. The low ionic and electronic conductivity of these polymers, however, limit their cycling performance at high active mass loadings. Moreover, Li–polysulfide (Li–PS) shuttling, a fatal phenomenon in...

Université de Fribourg

Stereospecific hydrogenolysis of benzylic alcohols over Pd/C

Harvey, Freya M. ; Bochet, Christian G.

In: The Journal of Organic Chemistry, 2020, vol. 85, no. 11, p. 7611–7619

Hydrogenolysis of tertiary benzylic alcohols on palladium on carbon (Pd/C) generally proceeds with inversion of configuration. However, little is known about the hydrogenolysis mechanism of primary and secondary benzylic alcohols. Literature precedents suggest that these substrates may interact differently with the catalyst. To study the mechanism, we synthesized a pair of deuterated...

Université de Fribourg

Metal nanoparticle–microbe interactions: synthesis and antimicrobial effects

Khan, Mujeebur R. ; Fromm, Katharina M. ; Rizvi, Tanveer F. ; Giese, Bernd ; Ahamad, Faheem ; Turner, Raymond J. ; Füeg, Michael ; Marsili, Enrico

In: Particle & Particle Systems Characterization, 2020, vol. 37, no. 5, p. 1900419

Metal nanoparticles (NPs), chalcogenides, and carbon quantum dots can be easily synthesized from whole microorganisms (fungi and bacteria) and cell‐free sterile filtered spent medium. The particle size distribution and the biosynthesis time can be somewhat controlled through the biomass/metal solution ratio. The biosynthetic mechanism can be explained through the ion‐reduction theory and...

Université de Fribourg

Indirect solvent assisted tautomerism in 4-substituted phthalimide 2-hydroxy-Schiff bases

Yordanov, Dancho ; Deneva, Vera ; Georgiev, Anton ; Crochet, Aurelien ; Fromm, Katharina M. ; Antonova, Liudmil

In: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2020, vol. 237, p. 118416

The paper presents the synthesis and characterization of two 4-substituted phthalimide 2-hydroxy-Schiff bases containing salicylic (4) and 2-hydroxy-1-naphthyl (5) moieties. The structural differences of 2-hydroxyaryl substituents, resulting in different enol/keto tautomeric behaviour, depending on the solvent environment were studied by absorption UV–Vis spectroscopy. Compound 5 is...

Université de Fribourg

Isolation of cellulose nanofibers from Oryza sativa residues via tempo mediated oxidation

Madivoli, Edwin S. ; Kareru, Patrick G. ; Gachanja, Anthony N. ; Mugo, Samuel M. ; Sujee, David M. ; Fromm, Katharina M.

In: Journal of Natural Fibers, 2020, p. 1–13

Cellulose nanocrystals (CNCs) or cellulose nanofibers (CNFs) with different morphologies, chemical, mechanical and physical properties can be obtained when microcrystalline cellulose is subjected to enzymatic, chemical or mechanical treatment. With the aim of utilizing cellulose nanofibrils (CNFs) from Oryza sativa, we isolated microcrystalline cellulose using the Kraft process, followed by...

Université de Fribourg

Li0.5Ni0.5Ti1.5Fe0.5(PO4)3/C electrode material for lithium ion batteries exhibiting faster kinetics and enhanced stability

Srout, Mohammed ; Kwon, Nam Hee ; Ben Youcef, Hicham ; Semlal, Nawal ; Fromm, Katharina M. ; Saadoune, Ismael

In: ACS Applied Materials & Interfaces, 2020, vol. 12, no. 16, p. 18496–18503

Natrium super ionic conductor (NASICON) materials providing attractive properties such as high ionic conductivity and good structural stability are considered as very promising materials for use as electrodes for lithium- and sodium-ion batteries. Herein, a new high-performance electrode material, Li0.5Ni0.5Ti1.5Fe0.5(PO4)3/C, was synthesized via the sol–gel method and was...

Université de Fribourg

Improvement of the electrochemical performance by partial chemical substitution into the lithium site of titanium phosphate-based electrode materials for lithium-ion batteries: LiNi0.25Ti1.5 Fe0.5(PO4)3

Srout, Mohammed ; Kazzi, Mario El ; Youcef, Hicham Ben ; M.Fromm, Katharina ; Saadoune, Ismael

In: Journal of Power Sources, 2020, vol. 461, p. 228114

Partial lithium substitution with nickel (0.25 of Ni2+ ion) in the previously reported Li1.5Fe0.5Ti1.5(PO4)3/C (LFTP@C) was performed to improve its structural and electrochemical properties. The new LiNi0.25Fe0.5Ti1.5(PO4)3/C (LNFTP@C) material was then tested as electrode for lithium ion batteries. In the voltage window 1.85V–3.0 V vs. Li+/Li, attractive electrochemical performances were...

Université de Fribourg

Use of EpiAlveolar lung model to predict fibrotic potential of multiwalled carbon nanotubes

Barosova, Hana ; Maione, Anna G. ; Septiadi, Dedy ; Sharma, Monita ; Haeni, Laetitia ; Balog, Sandor ; O’Connell, Olivia ; Jackson, George R. ; Brown, David ; Clippinger, Amy J. ; Hayden, Patrick ; Petri-Fink, Alke ; Stone, Vicki ; Rothen-Rutishauser, Barbara

In: ACS Nano, 2020, vol. 14, no. 4, p. 3941–3956

Expansion in production and commercial use of nanomaterials increases the potential human exposure during the lifecycle of these materials (production, use, and disposal). Inhalation is a primary route of exposure to nanomaterials; therefore it is critical to assess their potential respiratory hazard. Herein, we developed a three-dimensional alveolar model (EpiAlveolar) consisting of human...

Université de Fribourg

Lipid nanoparticles biocompatibility and cellular uptake in a 3D human lung model

Magalhães, Joana ; Pinheiro, Marina ; Drasler, Barbara ; Septiadi, Dedy ; Petri-Fink, Alke ; Santos, Susana G ; Rothen-Rutishauser, Barbara ; Reis, Salette

In: Nanomedicine, 2020, vol. 15, no. 3, p. 259–271

Aim: Design nanostructured lipid carriers (NLC) to facilitate drug delivery to tuberculosis-infected areas, exploiting macrophage mannose receptors and assess their uptake in a 3D human lung model. Materials & methods: NLCs and mannosylated-NLCs were synthetized and characterized. Their uptake and biocompatibility were tested in a 3D human lung model. Results: The formulations have...

Université de Fribourg

COFs meet graphene nanoribbons

Fritz, Patrick Walter ; Coskun, Ali

In: Chem, 2020, vol. 6, no. 5, p. 1046–1048

2D covalent organic frameworks (COFs) have received considerable attention because of their crystallinity, permanent porosity, and tunability, yet they exhibit low in-plane conductivity. In this issue of Chem, Fischer and co-workers report an approach for growing 2D COF thin films featuring high in-plane conductivity for potential use in organic electronics.