03 Fakultät Chemie

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Institute: search.filters.UBSInstitut.Max-Planck-Institut für FestkörperforschungPublication Type: search.filters.UBSTyp.ZeitschriftenartikelSubject: search.filters.subject.540

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Now showing 1 - 10 of 27
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    Designing covalent organic framework‐based light‐driven microswimmers toward therapeutic applications
    (2023) Sridhar, Varun; Yildiz, Erdost; Rodríguez‐Camargo, Andrés; Lyu, Xianglong; Yao, Liang; Wrede, Paul; Aghakhani, Amirreza; Akolpoglu, Birgul M.; Podjaski, Filip; Lotsch, Bettina V.; Sitti, Metin
    While micromachines with tailored functionalities enable therapeutic applications in biological environments, their controlled motion and targeted drug delivery in biological media require sophisticated designs for practical applications. Covalent organic frameworks (COFs), a new generation of crystalline and nanoporous polymers, offer new perspectives for light‐driven microswimmers in heterogeneous biological environments including intraocular fluids, thus setting the stage for biomedical applications such as retinal drug delivery. Two different types of COFs, uniformly spherical TABP‐PDA‐COF sub‐micrometer particles and texturally nanoporous, micrometer‐sized TpAzo‐COF particles are described and compared as light‐driven microrobots. They can be used as highly efficient visible‐light‐driven drug carriers in aqueous ionic and cellular media. Their absorption ranging down to red light enables phototaxis even in deeper and viscous biological media, while the organic nature of COFs ensures their biocompatibility. Their inherently porous structures with ≈2.6  and ≈3.4 nm pores, and large surface areas allow for targeted and efficient drug loading even for insoluble drugs, which can be released on demand. Additionally, indocyanine green (ICG) dye loading in the pores enables photoacoustic imaging, optical coherence tomography, and hyperthermia in operando conditions. This real‐time visualization of the drug‐loaded COF microswimmers enables unique insights into the action of photoactive porous drug carriers for therapeutic applications.
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    Confirmation of siderazot, Fe3N1.33, the only terrestrial nitride mineral
    (2021) Bette, Sebastian; Theye, Thomas; Bernhardt, Heinz-Jürgen; Clark, William P.; Niewa, Rainer
    Siderazot, the only terrestrial nitride mineral, was reported only once in 1876 to occur as coating on volcanic rocks in a fumarolic environment from Mt. Etna and, to date, has been neither confirmed nor structurally characterized. We have studied the holotype sample from the Natural History Museum, London, UK, originally collected by O. Silvestri in 1874, and present siderazot with epsilon-Fe3N-type crystal structure and composition of Fe3N1.33(7) according to crystal structure Rietveld refinements, in good agreement with electron microprobe analyses. Crystal structure data, chemical composition, and Raman and reflectance measurements are reported. Possible formation conditions are derived from composition and phase stability data according to synthetic samples.
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    On the thermal dimorphy of the strontium perrhenate Sr[ReO4]2
    (2024) Conrad, Maurice; Bette, Sebastian; Dinnebier, Robert E.; Schleid, Thomas
    Hygroscopic single crystals of a new hexagonal high‐temperature modification of Sr[ReO4]2 were prepared from a melt of Sr[ReO4]2 ⋅ H2O and SrCl2 ⋅ 6 H2O. The structure analysis of the obtained crystals by X‐ray diffraction revealed that the title compound crystallizes in the ThCd[MoO4]3‐type structure with the hexagonal space group P63/m and the lattice parameters a=1023.81(7) pm and c=646.92(4) pm (c/a=0.632) for Z=2 in its quenchable high‐temperature form. Two crystallographically independent Sr2+ cations are coordinated by oxygen atoms forming either octahedra or tricapped trigonal prisms, whereas the Re7+ cations are found in the centers of discrete tetrahedral meta‐perrhenate units [ReO4]-. Temperature‐dependent in‐situ PXRD studies of dry powder samples of Sr[ReO4]2 exhibited its thermal dimorphy with a phase‐transition temperature at 500-550 °C from literature‐known m‐Sr[ReO4]2 into the newly discovered h‐Sr[ReO4]2 (hexagonal).
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    High‐performance magnesium‐sulfur batteries based on a sulfurated poly(acrylonitrile) cathode, a borohydride electrolyte, and a high‐surface area magnesium anode
    (2020) Wang, Peiwen; Trück, Janina; Niesen, Stefan; Kappler, Julian; Küster, Kathrin; Starke, Ulrich; Ziegler, Felix; Hintennach, Andreas; Buchmeiser, Michael R.
    Post‐lithium‐ion battery technology is considered a key element of future energy storage and management. Apart from high gravimetric and volumetric energy densities, economic, ecologic and safety issues become increasingly important. In that regards, both the anode and cathode materials must be easily available, recyclable, non‐toxic and safe, which renders magnesium‐sulfur (Mg-S) batteries a promising choice. Herein, we present Mg-S cells based on a sulfurated poly(acrylonitrile) composite cathode (SPAN), together with a halogen‐free electrolyte containing both Mg[BH4]2 and Li[BH4] in diglyme and a high‐specific surface area magnesium anode based on Rieke magnesium powder. These cells deliver discharge capacities of 1400 and 800 mAh/gsulfur with >99 % Coulombic efficiency at 0.1 C and 0.5 C, respectively, and are stable over at least 300 cycles. Energy densities are 470 and 400 Wh/kgsulfur at 0.1 C and 0.5 C, respectively. Rate tests carried out between 0.1 C and 2 C demonstrate good rate capability of the cells. Detailed mechanistic studies based on X‐ray photoelectron spectroscopy and electric impedance spectroscopy are presented.
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    Monomeric and dimeric (aminomethylidene)phosphines and -arsines
    (1986) Becker, Gerd; Mayer, M.; Mundt, Otto; Riffel, Heinz; Wessely, Hans-Jürgen; Simon, Arndt
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    Sulfurized polypropylene as low‐cost cathode material for high‐capacity lithium‐sulfur batteries
    (2022) Du, Qian; Benedikter, Mathis; Küster, Kathrin; Acartürk, Tolga; Starke, Ulrich; Hoslauer, Jean‐Louis; Schleid, Thomas; Buchmeiser, Michael R.
    Among ‘beyond lithium ion’ energy storage, lithium sulfur (Li-S) batteries are one of the most promising technologies, as a result of the potential for high theoretical energy capacity at low cost. A key obstacle in exploiting the vast potential of Li-S batteries is the formation of soluble polysulfide species. Here, we report sulfurized polypropylene (S/PP‐500) synthesized in one‐step by reacting polypropylene (PP) with sulfur as a new polysulfide shuttle‐free cathode material for Li-S batteries. It exhibits a reversible capacity as high as 1000 mAh/gsulfur at 0.1 C and a sulfur loading of up to 68 wt%, which in turn allows for high sulfur loadings up to 47 % in the final cathode. The low‐cost starting materials together with the simple synthetic procedure and the good electrochemical performance in combination with a commercially available eslectrolyte make the S/PP‐500 a very promising cathode material for Li‐S batteries.
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    Cuttlebone-like V2O5 nanofibre scaffolds - advances in structuring cellular solids
    (2017) Knöller, Andrea; Runčevski, Tomče; Dinnebier, Robert E.; Bill, Joachim; Burghard, Zaklina
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    Towards recycling of LLZO solid electrolyte exemplarily performed on LFP/LLZO/LTO cells
    (2022) Ali Nowroozi, Mohammad; Iqbal Waidha, Aamir; Jacob, Martine; Aken, Peter A. van; Predel, Felicitas; Ensinger, Wolfgang; Clemens, Oliver
    All‐solid‐state lithium ion batteries (ASS‐LIBs) are promising due to their safety and higher energy density as compared to that of conventional LIBs. Over the next few decades, tremendous amounts of spent ASS‐LIBs will reach the end of their cycle life and would require recycling in order to address the waste management issue along with reduced exploitation of rare elements. So far, only very limited studies have been conducted on recycling of ASS‐LIBS. Herein, we investigate the recycling of the Li7La3Zr2O12 (LLZO) solid‐state electrolyte in a LiFePO4/LLZO/Li4Ti5O12 system using a hydrometallurgical approach. Our results show that different concentration of the leaching solutions can significantly influence the final product of the recycling process. However, it was possible to recover relatively pure La2O3 and ZrO2 to re‐synthesize the cubic LLZO phase, whose high purity was confirmed by XRD measurements.
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    Insights into the first multi-transition-metal containing Ruddlesden-Popper-type cathode for all-solid-state fluoride ion batteries
    (2024) Vanita, Vanita; Waidha, Aamir Iqbal; Vasala, Sami; Puphal, Pascal; Schoch, Roland; Glatzel, Pieter; Bauer, Matthias; Clemens, Oliver
    Promising cathode materials for fluoride-ion batteries (FIBs) are 3d transition metal containing oxides with Ruddlesden-Popper-type structure. So far, the multi-elemental compositions have not been investigated, but it could alternate the electrochemical performance similar to what has been found for cathode materials for lithium-ion batteries. In this study, we investigate RP type La2Ni0.75Co0.25O4.08 as an intercalation-based active cathode material for all-solid-state FIBs. We determine the structural changes of La2Ni0.75Co0.25O4.08 during fluoride intercalation/de-intercalation by ex situ X-ray diffraction, which showed that F- insertion leads to transformation of the parent phase to three different phases. Changes in the Ni and Co oxidation states and coordination environment were examined by X-ray absorption spectroscopy and magnetic measurements in order to understand the complex reaction behaviour of the phases in detail, showing that the two transition metals behave differently in the charging and discharging process. Under optimized operating conditions, a cycle life of 120 cycles at a critical cut-off capacity of 40 mA h g-1 against Pb/PbF2 was obtained, which is one of the highest observed for intercalation electrode materials in FIBs so far. The average coulombic efficiencies ranged from 85% to 90%. Thus, La2Ni0.75Co0.25O4.08 could be a promising candidate for cycling-stable high-energy cathode materials for all-solid-state FIBs.
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    Intermolekulare Sb···Sb-Wechselwirkungen im kristallinen Tetramethyldistiban (Element-Element-Bindungen ; 3)
    (1984) Mundt, Otto; Riffel, Heinz; Becker, Gerd; Simon, Arndt
    Tetramethyldistibane which shows a colour change from deep red to pale yellow upon melting, has been subjected to single-crystal x-ray diffraction analyses at -21° and -139°C (orthorhombic, Pnma, Z = 4, -139°C: a = 1150.9(3); b = 1136.8(2); c = 651.6(2) pm). The molecules adopt the antiperiplanar conformation with the crystallographically imposed symmetry m (c 3) and are aligned in extended linear antimony chains with short intermolecular contacts (-139 °C: Sb-Sb 283.8(1), Sb···Sb 367.8(1) pm; Sb-Sb...Sb 179.2°). The structure is compared with those of similar compounds.