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Publications (148)
The structure of supraparticles (SP) 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 o...
Superparamagnetic iron oxide nanoparticles (SPIONs) are prone to oxidation at elevated temperatures (>300 °C) and lose their magnetizability upon transition from magnetite/maghemite (γ‐Fe2O3 / Fe3O4) to hematite (α‐Fe2O3). Silica (SiO2) shells can effectively prevent this undesired effect up to ≈1000 °C. Herein, the study shows how to utilize SPION...
Temperature indicators trace (un)desired thermal impacts across their thermal history upon readout at every point of interest via defined irreversible signal changes. Ratiometric luminescent temperature indicators are attractive due to their fast, sensitive, contactless, spatially‐resolved, and self‐referenced readout. However, they have a limited...
The vulcanization process is widely used in industry for tire manufacturing. Therefore, zinc oxide is commonly utilized as an activator material, but unreacted zinc oxide remains in the final products and can be released into the environment with a significant impact. To reduce the amount of required zinc and to prevent leaching from tire material,...
Spray‐drying is a popular and well‐known “drying tool” for engineers. This perspective highlights that, beyond this application, spray‐drying is a very interesting and powerful tool for materials chemists to enable the design of multifunctional and hybrid materials. Upon spray‐drying, the confined space of a liquid droplet is narrowed down, and its...
Materials are the fundament of the physical world, whereas information and its exchange are the centerpieces of the digital world. Their fruitful synergy offers countless opportunities for realizing desired digital transformation processes in the physical world of materials. Yet, to date, a perfect connection between these worlds is missing. From t...
In a recently published article (Lange et al., 2023), we envisioned and discussed a tandem solar cell concept based on a perovskite/TOPCon architecture in p-i.n configuration, that utilizes a p+ /n+ polycrystalline silicon (poly-Si) tunnel junction and NiOx as hole transport material of the perovskite top cell. A direct contact of NiOx to p+ poly-S...
A novel GaPt-based supported catalytically active liquid metal solution (SCALMS) material is developed by exploiting the suprabead concept: Supraparticles, i.e. micrometer-sized particles composed of nanoparticles assembled by spray-drying, are bonded to millimeter-sized beads. The suprabeads combine macroscale size with catalytic properties of nan...
Liquid‐infused surfaces exhibit remarkable repellency properties toward water, oils, and complex fluids and are widely applied to maintain clean, operational, and high‐performing surfaces in various fields, from the biomedical sector to marine infrastructure. Polydopamine (PDA) forms an ideal base layer for the development of such coatings as it ad...
Robotic systems facilitate relatively simple human–robot interaction for non-robot experts, providing the flexibility to implement different processes. In this context, shorter process times, as well as an increased product and process quality could be achieved. Robots short time-consuming processes, take over ergonomically unfavorable tasks and wo...
The ability to molecularly engineer luminescent metal-organic frameworks is a powerful tool for the design of better performing rational temperature sensors. Lanthanide based MOF stand out as luminescent temperature sensors due to the high luminescence intensity and sharp emission lines of the lanthanides. The use of two different lanthanide cation...
Most analytical techniques used to study the surface chemical properties of superparamagnetic iron oxide nanoparticles (SPIONs) are barely suitable for in situ investigations in liquids, where SPIONs are mostly applied for hyperthermia therapy, diagnostic biosensing, magnetic particle imaging or water purification. Magnetic particle spectroscopy (M...
Nickel oxide (NiOx) is a promising hole transport material for perovskite/Si tandem solar cells. Various silicon cell architectures may be used as bottom cells. The polycrystalline (poly-Si) p+/n+ tunnel diode is expected to be a high-efficiency interconnection scheme between the two subcells of monolithic tandems in pin-configuration with high the...
The ability to molecularly engineer luminescent metal-organic frameworks is a powerful tool for the design of better performing rational temperature sensors. Lanthanide based MOF stand out as luminescent temperature sensors due to the high luminescence intensity and sharp emission lines of the lanthanides. The use of two different lanthanide cation...
The recent transition to H 2 -based energy storage demands for reliable H 2 sensors that allow for easy, fast, and reliable detection of leaks. Conventional H 2 detectors are based on the H 2 probes of changes of physical properties induced by subsurface H-atoms to a material, such as electrical conductivity. Herein, we report on highly reactive ga...
![Scanning electron micrographs of a sample of pure ³∞[Eu2(BDC)3(H2O)4]...](publication/366096770/figure/fig2/AS:11431281244722228@1715991927704/Scanning-electron-micrographs-of-a-sample-of-pure-Eu2BDC3H2O4-Eu-BDC-a-in_Q320.jpg)
Luminomagnetic composites have been synthesized that allow for an individual tuning of luminescence intensity, chromaticity and magnetization by combination of superparamagnetic, citrate‐stabilized iron oxide nanoparticles with the luminescent MOFs ³∞[Ln2(BDC)3(H2O)4] (Ln=Eu, Tb; BDC²⁻=terephthalate). The components are arranged to a concept of inv...
Optical microscale shear‐stress indicator particles are of interest for the in situ recording of localized forces, e.g., during 3D printing or smart skins in robotic applications. Recently developed particle systems are based on optical responses enabled by integrated organic dyes. They thus suffer from potential chemical instability and cross‐sens...
Counterfeit electronic products not only cause financial losses but also come with safety risks. The worst‐case failure scenario certainly is a fire event. Since manufacturers are liable for damages and suffer image loss, fire‐proof postmortem taggants are needed, enabling differentiation between originals and counterfeits even after a fire inciden...
Tuning the morphology of supraparticles can crucially influence their final properties and is, thus, important for their application in chemical, pharmaceutical, and food industries. The present study reveals how varied nanoparticle sizes, concentrations, and weight ratios in multicomponent dispersions influence the morphology of supraparticles ass...
Small‐sized temperature indicator additives autonomously record temperature events via a gradual irreversible signal change. This permits for instance the indication of possible cold‐chain breaches or failure of electronics but also curing of glues. Thus, information about the materials’ thermal history can be obtained upon signal detection at ever...
Sb‐substituted Cs2AgBiBr6 single crystals and powders were synthesized by various wet‐chemical routes as well as by solvent‐free mechanochemical synthesis. Phase purity and resulting optical properties of differently synthesized Sb‐substituted Cs2AgBiBr6 absorbers were investigated and compared. X‐ray diffraction confirmed that Sb‐substitution resu...
Nanoplastics are one of the main modern concerns in water pollution and are suspected to have severe negative impacts on their surrounding ecosystems. The use of superparamagnetic iron oxide nanoparticles (SPIONs) as remediation agents is a suggested approach to address this issue. Their nanoparticulate and switchable magnetic properties enable a h...
Hydrogen Sensors In article number 2112379, Tanja Bauer, Karl Mandel, and co‐workers, demonstrate micrometer‐sized supraparticles for rapid real‐time monitoring and irreversible recording of H2 gas via a distinct, eye‐readable two‐step color change. Key for the functionality is a three‐phase system within the mesoporous, multi‐component suprapartic...
Wet chemically deposited NiOx is a promising hole-transport material in perovskite/Si tandem solar cells due to its high work function, chemical stability, and low cost. However, it requires subsequent annealing that may lead to the formation of SiOz at the Si interface to the bottom cell. These layers of nm thickness exhibit non-stoichiometric che...
Small scratches and abrasion cause damage to packaging coatings. Albeit often invisible to the human eye, such small defects in the coating may ultimately have a strong negative impact on the whole system. For instance, gases may penetrate the coating and consequently the package barrier, thus leading to the degradation of sensitive goods. Herein,...
Indicators for H2 are crucial to ensure safety standards in a green hydrogen economy. Herein, the authors report micron‐scaled indicator supraparticles for real‐time monitoring and irreversible recording of H2 gas via a rapid eye‐readable two‐step color change. They are produced via spray‐drying SiO2 nanoparticles, AuPd nanoparticles, and indicato...
Sub)micrometer‐scaled identification (ID) taggants enable direct identification of arbitrary goods, thereby opening up application fields based on the possibility of tracking, tracing, and anti‐counterfeiting. Due to their small dimensions, these taggants can equip in principle even the smallest subcomponents or raw materials with information. To a...
Although citrates are commonly used to modify nanoparticles, attention is rarely paid to how the modification parameters affect the type of adsorption and, thus, possibly, the properties of the modified particles. The relevance of this and the significant impact it can have is demonstrated in this study by examining the effect of pH upon the modifi...
![Characterization of [CaF2:RE³⁺(w:x:y:z)] 30/[SiO2] 1 SP ID cores:...](publication/358863903/figure/fig3/AS:11431281244239312@1715879467823/Characterization-of-CaF2REwxyz30-SiO21-SP-ID-cores-a1relative-PL-spectra_Q320.jpg)
Tracking and tracing of objects are of paramount importance for realizing a Circular Economy and can be achieved by incorporating micrometer‐scaled luminescent identification (ID) taggants. While established systems are passive, displaying merely an ID feature, for monitoring a products’ life cycle, conscious taggants with stimuli‐triggered switcha...
Inside Back Cover
In article number 2101296, Thommes, Barr, Mandel, and co-workers used spray-drying as a scalable process that enables one to assemble freely chosen nanoparticles into supraparticles, i.e., microparticles with adjustable nanostructure, in combination with atomic layer deposition to deposit controlled thin films of different materia...
Spray‐drying is a scalable process enabling one to assemble freely chosen nanoparticles into supraparticles. Atomic layer deposition (ALD) allows for controlled thin film deposition of a vast variety of materials including exotic ones that can hardly be synthesized by wet chemical methods. The properties of coated supraparticles are defined not onl...
Avoiding harmful passivation of the lithium metal surface during its implementation as an anode material is a challenge to its use in rechargeable lithium metal batteries. It is critical to control the chemical composition and the morphology of the native passivation layer and to avoid contamination by lubricants or other substances involved in the...
Mit einem eingearbeiteten Pass aus klugem Rost lassen sich Gegenstände nachverfolgen. Er ist klein und lässt sich nicht nur außen an einem Produkt, sondern auch im Inneren anbringen.
Communicating Particles
In article number 2104189, Karl Mandel and co-workers report on a truly “communicating particle”. This single supraparticulate entity contains a unique optical ID and at the same time is capable of irreversibly changing further optical properties upon temperature encounter. Via a simple optical readout, the system is therefo...
In article 2100098, Mandel and co‐workers demonstrate how to solve the long known challenge to overcome the inhibition effects of citrate that are believed to hinder iron oxide nanoparticle formation from iron salt precursors when being present during the nanoparticle synthesis. This opens up routes to in‐situ modification of nano iron oxides, thus...
In article number 2101588, Karl Mandel and co‐workers report on how to obtain a micron‐sized magnetic supraparticle which carries a unique magnetic code. Via a hierarchical particle assembly principle, using magnetic nano building blocks, a nearly unlimited number of encoding options can be achieved. The particles enable magnetic tagging and tracin...
“Communicating particles” are reported that combine an identification (ID) taggant and a temperature recorder in one single entity—a micron-scaled supraparticle. The optical information carriers within the hybrid inorganic-organic supraparticles are three different types of luminescent nanoparticles, which can be read-out using single-wavelength ex...
Communicating objects are demanded for product security and the concepts of a circular economy or the Internet of Nano Things. Smart additives in the form of particles can be the key to equip objects with the desired materials intelligence as their miniaturized size improves applicability and security. Beyond their proposed identification by optica...
This study demonstrates how the method of thermally assisted oxidative precipitation in water can be opened for—the so far neglected—metal organic iron(II) complexes (herein: citrate) in order to obtain, in one step, ferromagnetic magnetite nanoparticles, possessing essential ligand properties. Based on a dedicated analysis of the specific precurso...
Herein, a simple model setup is presented to spray fine liquid droplets containing nanoparticles in an air stream transporting this toward a filter material. The nanoparticles are made of silica and tagged with a fluorescent dye in order to render the trace of the particles easily visible. The silica nanoparticles, in a first approximation, mimic v...
The controlled agglomeration of superparamagnetic iron oxide nanoparticles (SPIONs) was used to rapidly switch their magnetic properties. Small-angle X-ray scattering (SAXS) and dynamic light scattering showed that tailored iron oxide nanoparticles with phase-changing organic ligand shells agglomerate at temperatures between 5 °C and 20 °C. We obse...
In article number 2011089, Karl Mandel and co‐workers review the potential of supraparticles, i.e., particles assembled from nanoparticulate building blocks, in application fields that contribute to sustainability.
The indispensable transformation to a (more) sustainable human society on this planet heavily relies on innovative technologies and advanced materials. The merits of nanoparticles (NPs) in this context are demonstrated widely during the last decades. Yet, it is believed that the impact of particle‐based nanomaterials to sustainability can be even f...
Two series of organic–inorganic composite materials were synthesized through solvothermal imine condensation between diketopyrrolopyrrole dialdehyde DPP-1 and 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAPP) in the presence of varying amounts of either amino- or carboxy-functionalized superparamagnetic iron oxide nanoparticles (FeO). Whereas high...
Oxidative precipitation is a facile synthesis method to obtain ferromagnetic iron oxide nanoparticles from ferrous salts—with unexplored potential. The concentration of base and oxidant alone strongly affects the particle's structure and thus their magnetic properties despite the same material, magnetite (Fe3O4), is obtained when precipitated with...
Semi-continuous centrifugation is suggested as promising method to separate battery active materials from aqueous multi-component agglomerate dispersions. This is of special interest for direct recycling of active materials from decommissioned lithium-ion batteries. The separation of lithium iron phosphate (LFP) from carbon black C65 could be achie...
Herein, we report on the successful creation of a luminescent micron-sized magnet. A spray-drying approach was employed to do “chemistry in a droplet” in order to achieve opto-magnetic hybrids in...
Product identification tags are of great importance in a globalized world with increasingly complex trading routes and networks. Beyond currently used coding strategies, such as QR codes, higher data density, flexible application as well as miniaturization and readout indication are longed for in the next generation of security tags. In this work,...
Two series of organic-inorganic composite materials were synthesized through solvothermal imine condensation between diketopyrrolopyrrole dialdehyde DPP-1 and 5,10,15,20-tetrakis(4-aminophenyl)porphyrin ( TAPP ) in the presence of varying amounts of either amino- or carboxylate-functionalized superparamagnetic iron oxide nanoparticles ( FeO ). Wher...
Smart Surfaces
In article number 2000023, Karl Mandel and co‐workers present a new type of abrasion indicators based on supraparticles to determine shear stress to a surface. With these supraparticles, based on nanoparticular building blocks, a smart and communicating surface is developed which indicates shear stress by a luminescent turn‐on effect...
Slight mechanical damage on surfaces or coatings caused, for example, by shear stress, is hardly detectable by simple means. Therefore, shear stress indicator particles for the creation of “interactive and communicating” coatings are presented. These are core‐shell supraparticles obtained by a two‐step spray‐drying assembly process from nanoparticl...
A multi-component particle system was developed that combines the properties of white color, white light emission and strong magnetism on the macroscopic and microscopic scale. The system is constituted by combination of an inorganic white core with either hard or soft magnetic properties and a white light emitting MOF. The key towards this achieve...
Fluidized-bed electrodes could offer an interesting way to increase the electrode surface area applicable in electrochemical processes when the problem of poor electrical contact within the particle bed could be overcome. We recently demonstrated, that the contacting can be improved by the use of magnetizable electrode particles and the superpositi...