Journal articles and book contributions

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Romanyuk, Oleksandr; Paszuk, Agnieszka; Gordeev, Ivan; Wilks, Regan G.; Ueda, Shigenori; Hartmann, Claudia; Félix, Roberto; Bär, Marcus; Schlueter, Christoph; Gloskovskii, Andrei; Bartoš, I.; Nandy, Manali; Houdková, Jana; Jiříček, Petr; Jaegermann, Wolfram; Hofmann, Jan Philipp; Hannappel, Thomas
Combining advanced photoelectron spectroscopy approaches to analyse deeply buried GaP(As)/Si(100) interfaces : Interfacial chemical states and complete band energy diagrams. - In: Applied surface science, Bd. 605 (2022), 154630

The epitaxial growth of the polar GaP(100) on the nonpolar Si(100) substrate suffers from inevitable defects at the antiphase domain boundaries (APDs), resulting from mono-atomic steps on the Si(100) surface. Stabilization of Si(100) substrate surfaces with As is a promising technological step enabling the preparation of Si substrates with double atomic steps and reduced density of the APDs. In this paper, 4-50-nm-thick GaP epitaxial films were grown on As-terminated Si(100) substrates with different types of doping, miscuts, and As-surface termination by metalorganic vapor phase epitaxy (MOVPE). The GaP(As)/Si(100) heterostructures were investigated by X-ray photoelectron spectroscopy (XPS) combined with gas cluster ion beam (GCIB) sputtering and by hard X-ray photoelectron spectroscopy (HAXPES). We found residuals of As atoms in the GaP lattice (∼0.2-0.3 at.%) and a localization of As atoms at the GaP(As)/Si(100) interface (∼1 at.%). Deconvolution of core level peaks revealed interface core level shifts. In As core levels, chemical shifts between 0.5 and 0.8 eV were measured and identified by angle-resolved XPS measurements. Similar valence band offset (VBO) values of 0.6 eV were obtained, regardless of the doping type of Si substrate, Si substrate miscut or type of As-terminated Si substrate surface. The band alignment diagram of the GaP(As)/Si(1 0 0) heterostructure was deduced.



https://doi.org/10.1016/j.apsusc.2022.154630
Eckl, Maximilian; Böttcher, René; Wölk, Luca; Wingerath, Melina; Barbado Fernández, Carlos; Nascimento, M. Lucia; Göhler, Lukas; Stelzer, Daniel; Bund, Andreas
Elektrochemisches Glätten von Metallen durch ionenleitende Festkörper in schwach leitenden Lösungen. - In: WOMag, ISSN 2195-5891, Bd. 11 (2022), 6, S. 22-24

Link, Steffen; Ivanov, Svetlozar; Bund, Andreas
Elektrochemische Abscheidung von Silicium aus organischen Elektrolyten. - In: Galvanotechnik, ISSN 0016-4232, Bd. 113 (2022), 7, S. 877-887

Silicium (Si) ist ein wichtiger Rohstoff für viele industrielle Anwendungen, u. a. für die Mikroelektronik, die Photovoltaikindustrie und neuerdings auch innerhalb der elektrochemischen Energiespeicherung. Für die Erweiterung des technischen Anwendungsspektrums von Si sind jedoch anpassbare Abscheidungstechnologien erforderlich.



Ahmadkhaniha, Donya; Krümmling, Josef; Zanella, Caterina
Electrodeposition of high entropy alloy of Ni-Co-Cu-Mo-W from an aqueous bath. - In: Journal of the Electrochemical Society, ISSN 1945-7111, Bd. 169 (2022), 8, 082515, insges. 5 S.

This study aimed to deposit high entropy alloy (HEA) coatings with five different elements, Ni, Co, Cu, Mo, and W, from a single aqueous bath. The influence of pH, current density, and complex agent on the composition of deposited coating was examined. It was shown that Mo and W were codeposited mainly with Ni and Co. pH had the most impact on the codeposition of reluctant elements like Mo and W, while current density had the minimum effect. The deposited coating had a metallic, dense, and nodular morphology with configurational entropy of around 1.6 R.



https://doi.org/10.1149/1945-7111/ac87d5
Cheng, Pengfei; Wang, Dong; Schaaf, Peter
A review on photothermal conversion of solar energy with nanomaterials and nanostructures: from fundamentals to applications. - In: Advanced sustainable systems, ISSN 2366-7486, Bd. 6 (2022), 9, 2200115, S. 1-19

Solar energy is a green, sustainable, and de facto inexhaustible energy source for mankind. The conversion of solar energy into other forms of energy has attracted extensive research interest due to climate change and the energy crisis. Among all the solar energy conversion technologies, photothermal conversion of solar energy exhibits unique advantages when applied for water purification, desalination, high-temperature heterogeneous catalysis, anti-bacterial treatments, and deicing. In this review, the various photothermal conversion mechanisms based on different forms of heat release are summarized and some of the latest examples are presented. In addition, the necessary prerequisites for solar-driven photothermal materials toward their practical applications are also discussed. Further, the latest advances in photothermal conversion of solar energy are discussed, focusing on different types of photothermal applications. Finally, a summary is given and the challenges and opportunities in the photothermal conversion of solar energy are presented. This review aims to give a comprehensive understanding of emerging solar energy conversion technologies based on the photothermal effect, especially by using nanomaterials and nanostructures.



https://doi.org/10.1002/adsu.202200115
Bohm, Sebastian; Phi, Hai Binh; Moriyama, Ayaka; Runge, Erich; Strehle, Steffen; König, Jörg; Cierpka, Christian; Dittrich, Lars
Highly efficient passive Tesla valves for microfluidic applications. - In: Microsystems & nanoengineering, ISSN 2055-7434, Bd. 8 (2022), 1, 97, S. 1-12

A multistage optimization method is developed yielding Tesla valves that are efficient even at low flow rates, characteristic, e.g., for almost all microfluidic systems, where passive valves have intrinsic advantages over active ones. We report on optimized structures that show a diodicity of up to 1.8 already at flow rates of 20 μl s^-1 corresponding to a Reynolds number of 36. Centerpiece of the design is a topological optimization based on the finite element method. It is set-up to yield easy-to-fabricate valve structures with a small footprint that can be directly used in microfluidic systems. Our numerical two-dimensional optimization takes into account the finite height of the channel approximately by means of a so-called shallow-channel approximation. Based on the three-dimensionally extruded optimized designs, various test structures were fabricated using standard, widely available microsystem manufacturing techniques. The manufacturing process is described in detail since it can be used for the production of similar cost-effective microfluidic systems. For the experimentally fabricated chips, the efficiency of the different valve designs, i.e., the diodicity defined as the ratio of the measured pressure drops in backward and forward flow directions, respectively, is measured and compared to theoretical predictions obtained from full 3D calculations of the Tesla valves. Good agreement is found. In addition to the direct measurement of the diodicities, the flow profiles in the fabricated test structures are determined using a two-dimensional microscopic particle image velocimetry (μPIV) method. Again, a reasonable good agreement of the measured flow profiles with simulated predictions is observed.



https://doi.org/10.1038/s41378-022-00437-4
Hartmann, Robert; Puch, Florian
Development of a production process for environmentally friendly and resource-efficient molded parts consisting of load-appropriate reinforced wood-plastic composites :
Entwicklung eines Herstellungsprozesses für umweltfreundliche und ressourceneffiziente Formteile aus lastgerecht verstärkten Holz-Kunststoff-Verbunden. - In: Zeitschrift Kunststofftechnik, Bd. 18 (2022), 4, S. 203-233

Dieser Beitrag beschreibt einen Herstellungsprozess für umweltfreundliche und ressourceneffiziente Formteile aus neuartigen Holz-Kunststoff-Verbunden (HKV). Bei der Herstellung von HKV werden anisotrope mechanische Eigenschaften von langen, schlanken Holzspänen (Strands) durch deren lastgerechte Positionierung auf dreidimensionaler Werkzeugoberfläche anwendungsoptimiert ausgenutzt und umweltverträgliche duro- als auch thermoplastische Kunststoffe als Alternative zu den konventionellen formaldehyd- oder isocyanathaltigen Bindemitteln eingesetzt.



https://dx.doi.org/10.3139/O999.01042022
Liu, Jun; Zhao, Huaping; Wang, Zhijie; Hannappel, Thomas; Kramm, Ulrike; Etzold, Bastian; Lei, Yong
Tandem nanostructures: a prospective platform for photoelectrochemical water splitting. - In: Solar RRL, ISSN 2367-198X, Bd. 6 (2022), 9, 2200181, S. 1-33

A platform for efficient photoelectrochemical (PEC) water splitting must fulfil different requirements: the absorption of the solar spectrum should be maximized in use for charge carrier generation. To avoid recombination, fast separation of charge carriers is required and the energetic positions of the band structure(s) must be optimized with respect to the water splitting reactions. In these respects, constructing tandem nanostructures with rationally designed nanostructured units offers a potential opportunity to break the performance bottleneck imposed by the unitary nanostructure. So far, quite a few tandem nanostructures have been designed, fabricated, and employed to improve the efficiency of PEC water splitting, and significant achievements have been realized. This review focuses on the current advances in tandem nanostructures for PEC water splitting. Firstly, the state of the art for tandem nanostructures applied in PEC water splitting is summarized. Secondly, the advances in this field and advantages arising of employing tandem nanostructures for PEC water splitting are outlined. Subsequently, different types of tandem nanostructures are reviewed, including core-shell tandem nanostructured photoelectrode, the two-photoelectrode tandem cell, and the tandem nanostructures of plasmon related devices for PEC water splitting. Based on this, the future perspective of this field is proposed.



https://doi.org/10.1002/solr.202200181
Li, Yuhang; Wang, Dong; Liang, Zhengchen; Zeng, Lingxiao; Li, Wenxue; Xie, Peng; Ding, Qi; Zhang, Hong; Schaaf, Peter; Wang, Wei
Evaluating the optical response of heavily decorated black silicon based on a realistic 3D modeling methodology. - In: ACS applied materials & interfaces, ISSN 1944-8252, Bd. 14 (2022), 31, S. 36189-36199

Combining black silicon (BS), a nanostructured silicon containing highly roughened surface morphology with plasmonic materials, is becoming an attractive approach for greatly enhancing light-matter interactions with promising applications of sensing and light harvesting. However, precisely describing the optical response of a heavily decorated BS structure is still challenging due to the increasing complexity in surface morphology and plasmon hybridization. Here, we propose and fully characterize BS-based multistacked nanostructures with randomly distributed nanoparticles on the highly roughened nonflat surface. We demonstrate a realistic 3D modeling methodology based on parametrized scanning electron microscopy images that provides high-precision morphology details, successfully linking the theoretical analysis with experimental optical response of the complex nanostructures. Far-field calculations very nicely reproduce experimental reflectance spectra, revealing the dependency of light trapping on the thickness of the conformal reflector and the atop nanoparticle size. Near-field analysis clearly identifies three types of stochastic “hotspots”. Their contribution to the overall field enhancement is shown to be very much sensitive to the nanoscale surface morphology. The simulated near-field property is then used to examine the measured surface-enhanced Raman scattering (SERS) response on the multistacked structures. The present modeling approach combined with spectroscopic characterizations is expected to offer a powerful tool for the precise description of the optical response of other large-scale highly disordered realistic 3D systems.



https://doi.org/10.1021/acsami.2c05652
Zhao, Yuguo; Yan, Yong; Liu, Chunyue; Zhang, Dongtang; Wang, Dong; Ispas, Adriana; Bund, Andreas; Du, Biao; Zhang, Zhengdong; Schaaf, Peter; Wang, Xiayan
Plasma-assisted fabrication of molecularly imprinted NiAl-LDH layer on Ni nanorod arrays for glyphosate detection. - In: ACS applied materials & interfaces, ISSN 1944-8252, Bd. 14 (2022), 31, S. 35704-35715

An inorganic-framework molecularly imprinted NiAl layered double hydroxide (MI-NiAl-LDH) with specific template molecule (glyphosate pesticide, Glyp) recognition ability was prepared on Ni nanorod arrays (Ni NRAs) through electrodeposition followed by a low-temperature O2 plasma treatment. The freestanding Ni/MI-NiAl-LDH NRA electrode had highly enhanced sensitivity and selectivity. The electrocatalytic oxidation of Glyp was proposed to occur at Ni3+ centers in MI-NiAl-LDH, and the current response depended linearly on the Glyp concentration from 10.0 nmol/L to 1.0 μmol/L (R2 = 0.9906), with the limit of detection (LOD) being 3.1 nmol/L (S/N = 3). An exceptional discriminating capability with tolerance for other similar organophosphorus compounds was achieved. Molecular imprinting (N and P residues) affected the electronic structure of NiAl-LDH, triggering the formation of highly active NiOOH sites at relatively lower anodic potentials and substantially enhancing the electrocatalytic oxidation ability of the NiAl-LDH interface toward the C-N bonds in Glyp. In combination with the surface enrichment effect of MI-NiAl-LDH toward template molecules, the electrochemical oxidation signal intensity of Glyp increased significantly, with a greater peak separation from interfering molecules. These results challenge the common belief that the excellent performance of inorganic-framework molecularly imprinted interfaces arises from their specific adsorption of template molecules, providing new insight into the development of high-performance organic-pollutant-sensing electrodes.



https://doi.org/10.1021/acsami.2c08500