Publikationen

Electrochemical processes enable fast lithium extraction, for example, from brines, with high energy efficiency and stability. Lithium iron phosphate (LiFePO4) and manganese oxide (λ-MnO2) have usually been employed as the lithium gathering electrode material. Compared with λ-MnO2, LiFePO4 has a higher theoretical capacity and lower lithium insertion potential but suffers from low performance stability. Therefore, exploring the reason for capacity fading and putting forward an effective approach to address this issue is important. In this work, we studied the effect of additional present cations and dissolved oxygen on the stability of LiFePO4, using a rocking chair cell configuration to eliminate the effect of the other electrode. We found that adding Ca2+ to the solution and dissolved oxygen aggravate the capacity fading of LiFePO4, whereas Na+ and Mg2+ do not show an obvious influence on the stability of LiFePO4. By continuous nitrogen-flushing of the electrolyte and carbon coating of the electrode material, the stability of LiFePO4 was significantly enhanced. The lithium extraction capacity of LiFePO4/C is 21 mgLi gelectrode−1 with an energy consumption of 3.03 ± 0.5 W h molLi−1 and capacity retention of 82% in 10 cycles in 5 mM LiCl + 50 mM NaCl solution at a cell voltage range of −0.5 V to +0.5 V.

Abstract High-entropy materials (HEMs) with promising energy storage and conversion properties have recently attracted worldwide increasing research interest. Nevertheless, most research on the synthesis of HEMs focuses on a “trial and error” method without any guidance, which is very laborious and time-consuming. This review aims to provide an instructive approach to searching and developing new high-entropy energy materials in a much more efficient way. Toward materials design for future technologies, a fundamental understanding of the process/structure/property/performance linkage on an atomistic level will promote prescreening and selection of material candidates. With the help of computational material science, in which the fast development of computational capabilities that have a rapidly growing impact on new materials design, this fundamental understanding can be approached. Furthermore, high-throughput experimental methods, enabled by the advances in instrumentation and electronics, will accelerate the production of large quantities of results and stimulate the identification of the target products, adding knowledge in computational design. This review shows that combining computational preselection and verification by high-throughput can be an efficient approach to unveil the complexities of HEMs and design novel HEMs with enhanced properties for energy-related applications.

Quinone-containing materials have attracted significant attention for energy storage and electroswing carbon capture. Tailored redox-responsive core–shell particles are obtained in the present work via semicontinuous starved-feed emulsion polymerization and subsequent postmodification strategies with redox-responsive quinone moieties. The use of glycidyl methacrylate within the shell material offers the possibility of a ring-opening reaction with the redox-responsive 2-aminoanthraquinone (2-AAQ), which possesses a high affinity toward electrophilic carbon dioxide. The successful preparation of monodisperse particles, an essential prerequisite for colloidal self-assembly, was investigated by dynamic light scattering and transmission electron microscopy. The presence of reactive epoxy functionalities was achieved by the ring-opening reaction with the Preussmann reagent. Postsynthesis modification was investigated using X-ray photoelectron spectroscopy and cyclic voltammetry measurements. The redox-responsive core–shell particles were subjected to the melt-shear organization technique to prepare free-standing opal films featuring structural colors. The monodisperse 2-AAQ-containing particles were investigated for self-assembly inside conductive carbon felts, and their electrochemically mediated carbon capture capabilities were studied.

Abstract In this work, the preparation and fabrication of elastomeric opal films revealing reversible mechanochromic and pH-responsive features are reported. The core–interlayer–shell (CIS) particles are synthesized via stepwise emulsion polymerization leading to hard core (polystyrene), crosslinked interlayer (poly(methyl methacrylate-co-allyl methacrylate), and soft poly(ethyl acrylate-co-butyl acrylate-co-(2-hydroxyethyl) methacrylate) shell particles featuring a size of 294.9 ± 14.8 nm. This particle architecture enables the application of the melt-shear organization technique leading to elastomeric opal films with orange, respectively, green brilliant reflection colors dependent on the angle of view. Moreover, the hydroxyl moieties as part of the particle shell are advantageously used for subsequent thermally induced crosslinking reactions enabling the preparation of reversibly tunable mechanochromic structural colors based on Bragg's law of diffraction. Additionally, the CIS particles can be loaded upon extrusion or chemically by a postfunctionalization strategy with organic dyes implying pH-responsive features. This convenient protocol for preparing multi-responsive, reversibly stretch-tunable opal films is expected to enable a new material family for anti-counterfeiting applications based on external triggers.

Abstract The synthesis and characterization of polyferrocenylmethylene (PFM) starting from dilithium 2,2-bis(cyclopentadienide)propane and a Me2C[1]magnesocenophane is reported. Molecular weights of up to Mw = 11 700 g mol–1 featuring a dispersity, Ð, of 1.40 can be achieved. The material is studied by different methods comprising nuclear magnetic resonance (NMR) spectroscopy, matrix-assisted laser desorption/ionization time of flight (MALDI-ToF) mass spectrometry, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) measurements elucidating the molecular structure and thermal properties of these novel polymers. Moreover, cyclic voltammetry (CV) reveals quasi-reversible oxidation and reduction behavior and communication between the iron centers. Also, the crystal structure of a related cyclic hexamer is presented.

Subnanometer pores of carbon discriminate against ions based on their size. Capitalizing on such nuanced differences enables ion separation via charge/discharge cycling during ion electrosorption. Different ion uptake capacities in aqueous media with multiple, competing ions are also of high importance to understand capacitive deionization of surface water or industrial process water. In our experiments, we observed divalent cations sieving in pores smaller than 0.6 nm. By applying this phenomenon, a desalination cell with online concentration monitoring was used to study the ion-selectivity. We concluded that in pores below 0.6 nm, divalent Mg2+ and Ca2+ are entirely blocked, and the K+ over Na+ selectivity corresponds with their size ratio. Larger micropores show a preference for divalent cations with higher charge numbers. In both materials, a dynamic monovalent cation and divalent cation replacement dependent on the potential variation is observed.

Summary Advanced hydrogen technologies contribute essentially to the decarbonization of our industrialized world. Large-scale hydrogen production would benefit from using the abundantly available water reservoir of our planet’s oceans. Current seawater-desalination technologies suffer from high energy consumption, high cost, or low performance. Here, we report technology for water desalination at seawater molarity, based on a polymer ion-exchange membrane fuel cell. By continuously supplying hydrogen and oxygen to the cell, a 160-mM concentration decrease from an initial value of 600 mM is accomplished within 40 h for a 55-mL reservoir. This device’s desalination rate in 600 mM NaCl and substitute ocean water are 18 g/m2/h and 16 g/m2/h, respectively. In addition, by removing 1 g of NaCl, 67 mWh of electric energy is generated. This proof-of-concept work shows the high application potential for sustainable fuel-cell desalination (FCD) using hydrogen as an energy carrier.

T cells are activated by target cells via an intimate contact, termed immunological synapse (IS). Cellular mechanical properties, especially stiffness, are essential to regulate cell functions. However, T cell stiffness at a subcellular level at the IS still remains largely elusive. In this work, we established an atomic force microscopy (AFM)-based elasticity mapping method on whole T cells to obtain an overview of the stiffness with a resolution of ~60 nm. Using primary human CD4+ T cells, we show that when T cells form IS with stimulating antibody-coated surfaces, the lamellipodia are stiffer than the cell body. Upon IS formation, T cell stiffness is enhanced both at the lamellipodia and on the cell body. Chelation of intracellular Ca2+ abolishes IS-induced stiffening at the lamellipodia but has no influence on cell-body-stiffening, suggesting different regulatory mechanisms of IS-induced stiffening at the lamellipodia and the cell body.

In saliva and gingival crevicular fluid (GCF) soluble factors such as cytokines, chemokines and growth factors have shown a great potential serving as biomarkers for early detection and/or diagnosis of oral and systemic diseases. However, GCF and saliva, which one is a better source is still under debate. This study aimed to gain an overview of cytokines, chemokines and growth factors in saliva and GCF to pave the way for selecting suitable oral fluids for oral and systemic diseases. Multiplex cytokine assay was conducted to determine concentrations of cytokines, chemokines and growth factors in saliva and GCF samples from healthy subjects. The protocol for sample collection was carefully optimized. Stabilization, repeatability, and donor variation of the profiles were analyzed. We found that for different donors, cytokine and chemokine profiles showed unique patterns in saliva but similar patterns in GCF. In terms of growth factors, the profiles were individualized in saliva and GCF. All profiles stayed stable for the same healthy individual. In saliva, profiles of cytokines, chemokines and growth factors are individualized for different donors. In GCF, profiles of cytokines and chemokines are similar. Other factors, such as growth factors and T helper-related cytokines, are highly variable in donors. Profiles of soluble factors are not correlated in saliva and GCF. The comprehensive cytokine profiles in saliva and GCF reported in this work would serve as a good base for choosing promising cytokines for developing biomarkers in oral fluids.

The immune system provides our defense against pathogens and aberrant cells, including tumorigenic and infected cells. Motility is one of the fundamental characteristics that enable immune cells to find invading pathogens, control tissue damage, and eliminate primary developing tumors, even in the absence of external treatments. These processes are termed “immune surveillance.” Migration disorders of immune cells are related to autoimmune diseases, chronic inflammation, and tumor evasion. It is therefore essential to characterize immune cell motility in different physiologically and pathologically relevant scenarios to understand the regulatory mechanisms of functionality of immune responses. This review is focused on immune cell migration, to define the underlying mechanisms and the corresponding investigative approaches. We highlight the challenges that immune cells encounter in vivo, and the microfabrication methods to mimic particular aspects of their microenvironment. We discuss the advantages and disadvantages of the proposed tools, and provide information on how to access them. Furthermore, we summarize the directional cues that regulate individual immune cell migration, and discuss the behavior of immune cells in a complex environment composed of multiple directional cues.