A universal design strategy based on NiPS3 nanosheets towards efficient photothermal conversion and solar desalination. - In: Advanced functional materials, ISSN 1616-3028, Bd. 34 (2024), 8, 2310942, S. 1-11
2D nanomaterials are proposed as promising photothermal materials for interfacial photothermal water evaporation. However, low evaporation efficiency, the use of hazardous hydrofluoric solution, and poor stability severely limit their practical applications. Here, a mixed solvent exfoliation surface deposition (MSESD) strategy for the preparation of NiPS3 nanosheets and NiPS3/polyvinyl alcohol (PVA) converter is successfully developed. The converter is obtained by drop-casting the NiPS3/PVA nanosheets onto a sponge. The PVA is mainly deposited on the edge of NiPS3 nanosheets, which not only improves the stability of NiPS3 nanosheets, but also adheres to the sponge to prepare a 3D photothermal converter, which shows an evaporation rate of 1.48 kg m−2 h−1 and the average photothermal conversion efficiency (PTCE) of 93.5% under a light intensity of 1 kW m−2. The photothermal conversion mechanism reveals that the energy of absorbed photons in NiPS3 nanosheets can be effectively converted into heat through non-radiative photon transitions as well as multiple optical interactions. To the best of the knowledge, this is the first report on the application of 2D metal-phosphorus-chalcogen (MPChx) for solar desalination, which provides new insights and guidance for the development of high-performance 2D photothermal materials.
https://doi.org/10.1002/adfm.202310942
High performance photothermal carbon nanotubes/nanostructured hydrogel for solar electricity production and solar water sterilization. - In: Applied surface science, Bd. 643 (2024), 158680
Solar energy is a promising renewable energy source with the potential to contribute to sustainable development. Efficient photothermal conversion is critical for solar energy acquisition and conversion. Here, carbon nanotubes (CNTs) were gelatinized to obtain the nanostructured CNT/hydrogel, and then highly light-absorbing CNT/n-hydrogels with surface texture were obtained by replicating the micrometer structure from the black silicon (b-Si) surface onto CNT/hydrogels by using a PDMS mold. Through the synergistic effect of both surface texture and nanostructures, it demonstrates high efficiency of solar electricity production and solar sterilization. A small thermoelectric (TE) module with an area of 4 × 4 cm2 is integrated with CNT/n-hydrogel absorber for the investigation of photo-thermoelectric conversion. The output power of the CNT/n-hydrogel TE device is 1.42 W•m−2 under 1 sun. And by connecting four devices in series, it has successfully demonstrated for charging mobile phones under two different solar illuminations. This work provides a cost-effective and easy fabrication method for opening up the hydrogel as a photothermal absorber, which is low-cost, reproducible, high-efficiency solar water sterilization and high photothermal conversion efficiency.
https://doi.org/10.1016/j.apsusc.2023.158680
Photon-induced near-field interaction in ultrafast point-projection electron microscopy. - In: CLEO, (2023), JTu2A.133, insges. 2 S.
We report the first study of ultrafast, slow (<100 eV) free electron wavepackets with optical near fields. This interaction is probed in a point-projection-microscope with 50fs temporal resolution using strongly localized fields around a nano-antenna.
https://ieeexplore.ieee.org/document/10258768
Numerische Ermittlung von Zielgrößen und Prozessparametern des Einsatzhärtens unter Berücksichtigung des lokalen Beanspruchungszustandes versagensrelevanter Konstruktionsdetails :
Numerical determination of target values and process parameters of case hardening, taking into account the local stress state of failure-relevant construction details. - In: HTM - journal of heat treatment and materials, ISSN 2194-1831, Bd. 78 (2023), 6, S. 352-368
Through the thermochemical process of case hardening, the local material strength of steel components can be increased. In addition to the increase in stress due to the notch effect, the shape of construction details also has an effect on key component properties after case hardening, such as edge hardness and case hardening depth. The component-related specification of target values for case hardening is currently based on empirical values or expert knowledge. In addition, the effect of design details during case hardening is not taken into account when specifying process parameters in the control and regulation software of case hardening systems. This article presents a concept for the numerical determination of target values and process parameters for case hardening based on the stress state of the component. Compared to the empirically based determination of target values and process parameters for case hardening, the application of the concept makes it possible to adapt the case hardening of components to their stress in the failure range and thus significantly increase the energy and resource efficiency of case hardening.
https://doi.org/10.1515/htm-2023-0023
Gold nanosponges: fascinating optical properties of a unique disorder-dominated system. - In: Journal of the Optical Society of America, ISSN 1520-8540, Bd. 40 (2023), 6, S. 1491-1509
Nanoporous gold is a three-dimensional bulk material that is percolated with a random network of nanometer-sized ligaments and made by selective corrosion of bimetallic alloys. It has intriguing geometric, catalytic, and optical properties that have fascinated scientists for many decades. When such a material is made into the form of small, 100-nm-sized particles, so-called nanosponges emerge that offer much flexibility in controlling their geometric, electronic, and optical properties. Importantly, these particles act as an antenna for light that can efficiently localize optical fields on a deep subwavelength scale in certain hotspots at the particle surface. This makes such nanosponges an interesting platform for plasmonic sensing, photocatalysis, and surface-enhanced Raman spectroscopy. Since the optical properties of these nanosponges can be controlled to a large degree by tuning their geometry and/or composition, they have attracted increasing attention in recent years. Here, we provide a concise overview of the current state of the art in this field, covering their fabrication, computational modeling, and specifically the linear and nonlinear optical properties of individual and hybrid nanosponges, for example, plasmon localization in randomly disordered hotspots with a size <10 nm and a long lifetime with an exceptionally high Purcell factor. The resulting nonlinear optical and photoemission properties are discussed for individual and hybrid nanosponges. The results presented have strong implications for further applications of such nanosponges in photonics and photocatalysis.
https://doi.org/10.1364/JOSAB.479739
Characterization of plastic-metal hybrid composites joined by means of reactive Al/Ni multilayers - evaluation of occurring thermal regime. - In: Engineering for a changing world, (2023), 4.3.056, S. 1-16
Present challenges in material science and joining technology are ever more subject to the desire for lightweight construction and engineering. Plastic-metal composites are suitable material combinations but also require the development and investigation of appropriate joining technologies. A particularly promising approach is the application of reactive multilayer foils. As an innovative method, these foils provide the possibility of flexible and low-distortion joining of dissimilar materials. The underlying reaction mechanism offers fast exothermic reaction propagation with well-known exothermic power output while the energy source is introduced directly into the joining zone. In this work, hybrid lap joints between semi-crystalline polyamide 6 and structured austenitic stainless steel X5CrNi18-10 were joined using reactive Al/Ni multilayer foils. The self-propagating reaction provides immediate temperatures that are well above the melting point of used plastic but decays rapidly after only a few milliseconds. To support ongoing investigations regarding composite formation, analysis of occurring thermal regime is in the focus of this work. Conducted experiments are supported by accompanying thermal simulation in ANSYS Workbench. Besides the estimation regarding sensitivity of thermal material parameters the evaluation of formed melting zone and resulting thermally influenced area is a central topic.
https://doi.org/10.22032/dbt.58913
Microstructure and properties of as-cast Zr-2.5Nb-1X (X = Ru, Mo, Ta and Si) alloys for biomedical application. - In: Rare metals, ISSN 1867-7185, Bd. 42 (2023), 10, S. 3497-3509
https://doi.org/10.1007/s12598-023-02291-3
Das physikalische Praktikum : Handbuch 2023/2024 für Studentinnen und Studenten der Physik. - Göttingen : Universitätsverlag Göttingen, 2023. - (Universitätsdrucke)
Gate-tunable hysteresis response of field effect transistor based on sulfurized Mo. - In: AIP Advances, ISSN 2158-3226, Bd. 13 (2023), 9, 095224, S. 095224-1-095224-7
Hysteresis effects and their tuning with electric fields and light were studied in thin film molybdenum disulfide transistors fabricated from sulfurized molybdenum films. The influence of the back-gate voltage bias, voltage sweep range, illumination, and AlOx encapsulation on the hysteresis effect of the back-gated field effect transistors was studied and quantified. This study revealed the distinctive contribution of MoS2 surface, MoS2/SiO2 interface defects and their associated traps as primary sources of of hysteresis.
https://doi.org/10.1063/5.0165868
Broadband solar energy harvesting enabled by micro and nanostructured materials. - Ilmenau : Universitätsbibliothek, 2023. - 1 Online-Ressource (IV, 145 Seiten)
Technische Universität Ilmenau, Dissertation 2023
In der kommenden Ära des "Carbon Peak und der Kohlenstoffneutralität" ist es besonders wichtig, neue Energietechnologien zu entwickeln, die kostengünstig, umweltfreundlich und im industriellem Maßstab herstellbar sind, um die herkömmlichen fossilen Brennstoffe zu ersetzen, die weithin als Verursacher des Treibhauseffekts und häufiger extremer Wetterlagen gelten. Solarenergie ist sozusagen eine unerschöpfliche Energieform, die jedem Land der Erde kostenlos zur Verfügung steht. Daher ist sie im Vergleich zu Kernenergie, Windenergie und blauer Energie die vielversprechendste Alternative zu fossiler Energie. In dieser Arbeit werden breitbandige Materialien zur Gewinnung von Solarenergie als Lichtabsorber für Anwendungen zur Umwandlung von Solarenergie, wie Stromerzeugung, Wasserdampferzeugung und Wasserstofferzeugung, vorgestellt. Zunächst wird schwarzes Silizium (b-Si) mit einer Vielzahl von Mikro-Nanostrukturen durch reaktives Ionenätzen (RIE) hergestellt. Die so hergestellten b-Si-Proben mit ultra-breitbandiger Lichtabsorption können für die photo-thermoelektrische (P-TE) Stromerzeugung, die photothermische (PT) Wasserverdampfung und die photoelektrochemische (PEC) Wasserreduktion verwendet werden, was die Leistung der Solarenergieumwandlung aufgrund ihrer hervorragenden Lichtabsorption im gesamten Sonnenspektrum verbessert. Darüber hinaus wurde eine metastabile Atomlagenabscheidung (MS-ALD) mit Selbstorganisation zur Herstellung großflächiger plasmonischer 3D-AgSiO2 Hybrid-Nanostrukturen entwickelt. Diese zeigen auch eine ultrabreitbandige sehr hohe Absorption im gesamten Sonnenspektrum. Wenn sie für die P-TE- und PT-Wasserverdampfung verwendet werden, verbessert sich die Leistung der Solarenergieumwandlung im Vergleich zu b-Si-Proben.
https://doi.org/10.22032/dbt.57584