Publikationen

Herein, a study dealing with a progress on palladium (Pd) electrocatalysts for an efficient glycerol electrooxidation in model aqueous and real fermentation solutions with special focus on some physicochemical parameters (e.g., the impact of adsorption stage of multiple species, presence of oxygen, influence of anodic limits and Pd-size) was conducted. During the course of investigations by tandem of an optical oxygen minisensor and cyclic voltammetry a significant impact of oxygen on the efficiency of glycerol electrooxidation on Pd electrocatalysts at alkaline pH in model aqueous and yeast fermentation media was revealed. The obtained knowledge was used for the optimization of an assay utilizing Pd-sensing layers for glycerol determination and quantification in yeast fermentation medium. Received results showed a satisfactory agreement with a control measurement carried out by gas chromatography mass-spectrometry.

The development of flexible and wearable electronics has grown in recent years with applications in different fields of industry and science. Consequently, the necessity of functional, flexible, safe, and reliable energy storage devices to meet this demand has increased. Since the classical electrochemical systems face structuration and operational limitations to match the needs of flexible devices, novel approaches have been in the research spotlight: gel polymer electrolytes (GPEs). Combining comparable ionic conductivity with liquid electrolytes with desirable mechanical stability, GPEs have been investigated in various electrochemical applications in sensors, actuators, and energy storage. This versatile class of quasi-solid material finds applications in the different components of energy storage devices. They are being investigated as electrodes, binders, electrolytes, and stand-alone systems due to desirable physical-chemical characteristics such as a wider potential operational window and high adhesion to solid electrode materials. Coalescing a liquid phase occluded into an entangled 3D polymeric matrix, these materials withstand elevated mechanical stress such as strain and compression, and they are also interesting materials for various applications. Moreover, they allow further functionalization to match the specific requirements of various energy storage systems. In this review, we summarize different applications of GPEs in energy storage devices, highlighting many valuable properties and emphasizing their enhancements compared to classical liquid electrochemical energy storage systems.

Environmentally friendly polymers such as cellulose acetate (CA) and chitosan (CS) were used to obtain electrospun fibers for Cu2+, Pb2+, and Mo6+ capture. The solvents dichloromethane (DCM) and dimethylformamide (DMF) allowed the development of a surface area of 148 m2 g−1 for CA fibers and 113 m2 g−1 for cellulose acetate/chitosan (CA/CS) fibers. The fibers were characterized by IR-DRIFT, SEM, TEM, CO2 sorption isotherms at 273 K, Hg porosimetry, TGA, stress-strain tests, and XPS. The CA/CS fibers had a higher adsorption capacity than CA fibers without affecting their physicochemical properties. The capture capacity reached 102 mg g−1 for Cu2+, 49.3 mg g−1 for Pb2+, and 13.1 mg g−1 for Mo6+. Furthermore, optimal pH, adsorption times qt, and C0 were studied for the evaluation of kinetic models and adsorption isotherms. Finally, a proposal for adsorbate-adsorbent interactions is presented as a possible capture mechanism where, in the case of Mo6+, a computational study is presented. The results demonstrate the potential to evaluate the fibers in tailings wastewater from copper mining.

MXene is investigated as an electrode material for different energy storage systems due to layered structures and metal-like electrical conductivity. Experimental results show MXenes possess excellent cycling performance as anode materials, especially at large current densities. However, the reversible capacity is relatively low, which is a significant barrier to meeting the demands of industrial applications. This work synthesizes N-doped graphene-like carbon (NGC) intercalated Ti3C2Tx (NGC-Ti3C2Tx) van der Waals heterostructure by an in situ method. The as-prepared NGC-Ti3C2Tx van der Waals heterostructure is employed as sodium-ion and lithium-ion battery electrodes. For sodium-ion batteries, a reversible specific capacity of 305 mAh g−1 is achieved at a specific current of 20 mA g−1, 2.3 times higher than that of Ti3C2Tx. For lithium-ion batteries, a reversible capacity of 400 mAh g−1 at a specific current of 20 mA g−1 is 1.5 times higher than that of Ti3C2Tx. Both sodium-ion and lithium-ion batteries made from NGC-Ti3C2Tx shows high cycling stability. The theoretical calculations also verify the remarkable improvement in battery capacity within the NGC-Ti3C2O2 system, attributed to the additional adsorption of working ions at the edge states of NGC. This work offers an innovative way to synthesize a new van der Waals heterostructure and provides a new route to improve the electrochemical performance significantly.

The demand for electronic devices that utilize lithium is steadily increasing in this rapidly advancing technological world. Obtaining high-purity lithium in an environmentally friendly way is challenging by using commercialized methods. Herein, we propose the first fuel cell system for continuous lithium-ion extraction using a lithium superionic conductor membrane and advanced electrode. The fuel cell system for extracting lithium-ion has demonstrated a twofold increase in the selectivity of Li+/Na+ while producing electricity. Our data show that the fuel cell with a titania-coated electrode achieves 95% lithium-ion purity while generating 10.23 Wh of energy per gram of lithium. Our investigation revealed that using atomic layer deposition improved the electrode's uniformity, stability, and electrocatalytic activity. After 2000 cycles determined by cyclic voltammetry, the electrode preserved its stability.

Hybrid core–shell nanoparticles with metal cores and conductive polymer shells yield materials that are sinter-free and highly conductive but mechanically weak. Conventional composites of such nanoparticles are electrically insulating. Here, we introduce microscale phase-separated nanocomposites of hybrid gold-PEDOT:PPS particles in insulating poly(vinyl alcohol) (PVA). They combine electrical conductivities of up to 2.1 × 105 S/m at 10 vol % PVA with increased mechanical adhesion on polyethylene terephthalate and glass substrates. We studied the effects of the PVA molecular weight, hydrolyzation degree, and volume fraction. Composites with 10 vol % highly hydrolyzed PVA at a MW of 89–98 kDa had the highest conductivities and stabilities; highly hydrolyzed PVA even increased the conductivity of the hybrid particle layers. We propose the formation of hydrogen bonds between PVA and PEDOT:PSS that lead to demixing and the formation of stable, structured composites. Finally, we demonstrated the inkjet-printability of inks containing PVA in water with viscosities of 1.6–2.0 Pa s at 50.1 s–1 and prepared bending-resistant electrical leads.

We numerically study a discretized Vicsek model (DVM) with particles orienting in q possible orientations in two dimensions. The study investigates the significance of anisotropic orientation and microscopic interaction on macroscopic behavior. The DVM is an off-lattice flocking model like the active clock model (ACM; Chatterjee et al 2022 Europhys. Lett.138 41001) but the dynamical rules of particle alignment and movement are inspired by the prototypical Vicsek model (VM). The DVM shows qualitatively similar properties as the ACM for intermediate noise strength where a transition from macrophase to microphase separation of the coexistence region is observed as q is increased. But for small q and noise strength, the liquid phase appearing in the ACM at low temperatures is replaced in the DVM by a configuration of multiple clusters with different polarizations, which does not exhibit any long-range order. We find that the dynamical rules have a profound influence on the overarching features of the flocking phase. We further identify the metastability of the ordered liquid phase subjected to a perturbation.

Extracellular vesicles (EVs), lipid-enclosed structures released by virtually all life forms, have gained significant attention due to their role in intercellular and interorganismal communication. Despite their recognized importance in disease processes and therapeutic applications, fundamental questions about their primary function remain. Here, we propose a different perspective on the primary function of EVs, arguing that they serve as essential elements providing membrane area for long-distance, contact-dependent cellular communication based on protein-protein interaction. While EVs have been recognized as carriers of genetic information, additional unique advantages that they could provide for cellular communication remain unclear. Here, we introduce the concept that the substantial membrane area provided by EVs allows for membrane contact-dependent interactions that could be central to their function. This membrane area enables the lateral diffusion and sorting of membrane ligands like proteins, polysaccharides or lipids in two dimensions, promoting avidity-driven effects and assembly of co-stimulatory architectures at the EV-cell interface. The concept of vesicle-induced receptor sequestration (VIRS), for example, describes how EVs confine and focus receptors at the EV contact site, promoting a dense local concentration of receptors into signalosomes. This process can increase the signalling strength of EV-presented ligands by 10-1000-fold compared to their soluble counterparts. The speculations in this perspective advance our understanding of EV-biology and have critical implications for EV-based applications and therapeutics. We suggest a shift in perspective from viewing EVs merely as transporters of relevant nucleic acids and proteins to considering their unique biophysical properties as presentation platforms for long-distance, contact-dependent signalling. We therefore highlight the functional role of the EV membrane rather than their content. We further discuss how this signalling mechanism might be exploited by virus-transformed or cancer cells to enhance immune-evasive mechanisms.

The structure of supraparticles (SPs) is a key parameter for achieving advanced functionalities arising from the combination of different nanoparticle (NP) types in one hierarchical entity. However, whenever a droplet-assisted forced assembly approach is used, e.g., spray-drying, the achievable structure is limited by the inherent drying phenomena of the method. In particular, mixed NP dispersions of differently sized colloids are heavily affected by segregation during the assembly. Herein, the influence of the colloidal arrangement of Pt and SiO2 NPs within a single supraparticulate entity is investigated. A salt-based electrostatic manipulation approach of the utilized NPs is proposed to customize the structure of spray-dried Pt/SiO2 SPs. By this, size-dependent separation phenomena of NPs during solvent evaporation, that limit the catalytic performance in the reduction of 4-nitrophenol, are overcome by achieving even Pt NP distribution. Additionally, the textural properties (pore size and distribution) of the SiO2 pore framework are altered to improve the mass transfer within the material leading to increased catalytic activity. The suggested strategy demonstrates a powerful, material-independent, and universally applicable approach to deliberately customize the structure and functionality of multi-component SP systems. This opens up new ways of colloidal material combinations and structural designs in droplet-assisted forced assembly approaches like spray-drying.

Soft lithography, in particular microcontact printing (µCP), represents a well-established and widespread class of lithographic patterning techniques. It is based on a directed deposition of molecules or colloidal particles by a transfer process with a micro-structured stamp. A critical aspect of µCP is the adhesion cascade that enables the directed transfer of the objects. Here, the interfacial properties of a µCP-stamp are tuned electrochemically to modify the adhesion cascade. During the printing process, the µCP-stamp is submerged in an electrolyte solution and acted as a working electrode whose surface properties depended on the externally applied potential, thus enabling in situ rapid switching of its adhesion properties. As a proof of principle, defined particle patterns are selectively removed from a monolayer of colloidal particles. The adhesion at the particle/solid interface and the transfer mechanisms are determined by using the colloidal probe technique based on atomic force microscopy (AFM). In this case, a single particle is brought into contact with an electrode with the same surface chemistry as the µCP-stamp. Hence, it became possible to determine the electrochemical potential ranges suitable to establish an adhesion cascade.