Dr.-Ing. Markus Beckers

🔗💻🔎 DOI: https://lnkd.in/dWBqbKyN 🧑📖 Evaluation of the operational curve for heat storage technology using n-octacosane/low-density as a binding material 👨‍⚖️ 🏫 ©️ Reza Abdu Rahman, Sulistyo Sulistyo, Mohamad Said Kartono Tony Suryo Utomo, Robertus Dhimas Dhewangga Putra (Universitas Diponegoro, Indonesia) Keywords: #binding #material, n-octacosane, #operational #energy, #phase #transition, #energy #storage Abstract Heat storage technology has a critical role for a number of applications involving renewable thermal energy (such as solar water heater). The application of wax (n-octacosane/OCT) as a medium for storing heat brings many positive influences for the system. However, the operational curve is undesirable for the OCT-based energy storage, which makes it necessary to use a binding material. The present work employed LD-class polymer (LDPE) and linear-LDPE as binding materials for OCT. The mixture is prepared through mechanical hot stirring, which comes into two categories: SOCT1 (OCT/LD) and SOCT2 (OCT/LLD). The assessment through the calorimetry method shows an increment in transition temperature for SOCT with a value of 2.1 °C and 5.5 °C. This contributes to the variation of fusion energy for solid-liquid change for both materials, which amounted to 132.05 J/g (SOCT1) and 113.4 J/g (SOCT2). Another assessment related to its chemical and structural phase demonstrates that SOCT has an identical structure to OCT, indicating that SOCT is mixed physically. At the operational level, SOCT is more optimal than OCT according to the indicator related to charge and discharge duration for energy exchange. SOCT1 demonstrates a short plateau line as the indication of a steady transition between 65.4–67.9 °C, while SOCT2 indicates the average heating rate, which is higher than for single OCT. The heat releasing curve for SOCT1 varies at a lower value between 1.92 °C/min and 0.77 °C/min, while SOCT2 has the lowest variation, which is only 0.17 °C/min. Moreover, the self-insulation for SOCT2 has the lowest rate, which is only 0.3 °C/min. The evaluation and analysis from this work show that SOCT is reliable to increase the operational curve of OCT and can be implemented for thermal systems.

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#QTNano: Metal Clusters Interaction with CeO2 Surfaces The study of transition metal (TM) clusters supported on ceria (CeO2) is crucial for advancing various technological applications, including catalysis, energy storage, and environmental protection. Addressing these questions can lead to more efficient and effective use of CeO2-based materials. Below, we summarize few findings from one old publication from our group based on density functional theory (DFT) calculations for the interaction of 13-atom TM clusters (specifically Pd, Ag, Pt, and Au) with the CeO2(111) surface. Cluster Structure and Stability: The TM13 clusters form stable, pyramidal-like structures on the CeO2(111) surface in their lowest energy configurations. The arrangement follows a specific stacking sequence: TM atoms at the top, followed by layers of four and eight TM atoms, and finally the CeO2(111) surface. These clusters tend to adopt two-dimensional structures only at higher energy states. Oxidation State Changes: The interaction between the TM clusters and the CeO2 surface induces a change in the oxidation state of a few Ce atoms in the topmost layer. Specifically, three out of sixteen Ce atoms change from CeIV (which has itinerant f-electrons) to CeIII (which has localized f-electrons). This alteration in oxidation state is a critical factor influencing the material's properties and reactivity. Charge Flow Dynamics: The study revealed a significant charge transfer from the TM atoms to the CeO2 surface. This charge flow is driven by the difference in electronegativity between the TM and oxygen (O) atoms. However, the charge distribution is not uniform due to the pressure exerted by the TM clusters on the underlying O ions. This pressure causes a decrease in the ionic charge of the O ions beneath the cluster and an increase in the charge of the surrounding O ions. Strain and Structural Implications: The charge flow predominantly from the TM8 layer to the topmost O layer affects the Ce atoms' ability to transfer charge to the O atoms. This results in a decreased effective cationic charge for some Ce atoms, causing them to change their oxidation state from IV to III. The larger size of the CeIII cations introduces strain within the topmost Ce layer, which subsequently impacts the location of the CeIII cations and the overall structure of the TM13 clusters. Why This Matters: (1) Catalysis -- Many catalytic processes depend on the oxidation states of Ce atoms. (2) Energy Storage -- CeO2 is used in solid oxide fuel cells and other energy storage systems. Insights into how TM clusters affect the material's properties can lead to more efficient energy storage solutions. (3) Environmental Protection -- CeO2-based materials are used in environmental applications such as pollutant removal. https://lnkd.in/dfnT7VYA

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“Antioil-fouling Superoleophobic-Superhydrophilic Nanofibrous Membranes for Separation of Immiscible Oil-water Mixtures and Emulsion,” ACS Applied Nano Materials 7, 17621-17629 (2024). Superoleophobic-superhydrophilic surfaces have been used for applications in the fabrication of antioil-fouling smart textiles and for immiscible oil−water mixtures and emulsions separation. Typically, these surfaces are constructed by depositing coatings with selective superwetting properties on porous structures. The facile electrospun technique involves the deposition of polymer solutions or melts through an electric field, resulting in nanometer-sized fibers that form nanofibrous membranes with hierarchical structures and a large specific surface area. In this study, superoleophobicsuperhydrophilic nanofibrous membranes were prepared by blending perfluorooctanoic acid and polyacrylonitrile polymers and fluorinated TiO2 nanoparticles and electrospinning them. The prepared nanofibrous membranes exhibit superoleophobic and superhydrophilic properties, along with antioil-fouling characteristics. These membranes can separate immiscible oil−water mixtures and oil-in-water emulsions. This superoleophobicsuperhydrophilic nanofibrous membranes have broad applications in industry and for environmental protection.

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#QTNano: Two-Dimensional Perovskite Materials Perovskite-based solar cells have emerged as a promising technology due to their impressive efficiency and potential for low-cost production. However, two significant challenges remain: efficiently managing the material's stability from environmental degradation and eliminating toxic lead (Pb) from its composition. A possible solution lies in using thin films of two-dimensional (2D) perovskite materials and replacing lead with less harmful elements like germanium (Ge) and tin (Sn). This approach not only addresses the toxicity issue but also enhances the performance of the solar cells. Researchers have delved into the atomic-level differences between traditional three-dimensional (3D) perovskites and their innovative 2D counterparts. Using advanced computational methods, they have compared various physical and chemical properties of these materials. Their findings reveal that 2D perovskites exhibit stronger internal bonding due to the presence of organic spacers, which increases their stability. This stability is crucial for maintaining the material's integrity and performance over time. Moreover, the study highlights that these 2D materials have unique electronic and optical properties that make them highly effective in solar energy applications. For instance, lead-free perovskites made with germanium and tin show optimal band gaps for converting sunlight into electricity. https://lnkd.in/dhmthYa9

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【Self-Powered Terahertz Modulators Based on Metamaterials, Liquid Crystals, and Triboelectric Nanogenerators】 ACS Applied Materials & Interfaces ( IF 9.5 ) Pub Date : 2024-06-13 , DOI: 10.1021/acsami.4c04251 6G communication mainly occurs in the THz band (0.1–10 THz), which can achieve excellent performance. Self-powered THz modulators are essential for achieving better conduction, modulation, and manipulation of THz waves. Herein, a self-powered terahertz modulator, which is based on metamaterials, liquid crystals (LCs), and rotary triboelectric nanogenerators (R-TENGs), is proposed to realize the driving of different array elements. The corresponding designs can achieve an integrated design and preparation method for dynamic spectrum-reconfigurable liquid crystal metamaterials. In addition, for the type of cross-structure metamaterial liquid crystal box, a phase modulation of 1 GHz is achieved at frequencies of 0.117 and 0.161 THz with modulation depths of 13 and 11%, respectively. Because the R-TENG with a multifan blade and circular electrodes can generate 18 peaks of electric output in every rotation, it can successfully provide sufficient frequency alternating-current electric energy to drive the terahertz modulator and achieve a self-powered function. Our findings lay a solid theoretical foundation for further building self-powered THz communication systems and promote the development of a theoretical system for LC-driving spectrum-reconfigurable devices in the THz domain. https://lnkd.in/eWB3p9QN

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🔬 Revolutionizing Material Discovery: Closing the Loop Between Theory, Processing, and Characterization 🔬 The need to develop new and better materials is paramount, impacting a broad range of applications from batteries and solar cells to structural ceramics. This challenge mirrors the current efforts in organic chemistry focused on small molecule prediction and synthesis. However, in materials science, the challenge extends beyond prediction to include processing and characterization. Here's why this is so critical: 📢 Processing and Characterization: Unlike organic molecules, where a molecule is a molecule no matter the synthetic path, materials require detailed understanding of the microstructure. The way atoms connect and interact within a material dictates its properties, making this step crucial. 💡 Composition vs. Microstructure: While materials can be represented by their composition, molar fractions of elements alone are insufficient. What truly matters is the microstructure—from atomic to macroscopic levels. This includes how atoms are arranged and how different phases and structures interact within the material. 🕯 Complexity of Microstructures: Describing and controlling material microstructures is far more complex than dealing with molecules. Microstructures are influenced by synthesis methods and often involve intricate details, such as grain boundaries and domain segregation, which significantly impact properties but are difficult to observe and control. 🔔 Need for Advanced Characterization: To effectively design and optimize materials, we need sophisticated methods to describe and characterize these systems. This is the first step toward knowledge-based design. Hence, closing the materials design loop necessitates placing advanced electron and scanning probe microscopies at the forefront. By focusing on these aspects, we can drive innovation in material discovery, leading to breakthroughs that will benefit numerous technologies and industries. Let’s work together to bridge the gap between theory, processing, and characterization, and unlock the full potential of materials science! 🌟🔍🧪 #MaterialsScience #Innovation #Research #Characterization #Microstructure #AdvancedMaterials #ElectronMicroscopy #ScanningProbeMicroscopy #ScientificDiscovery

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Ionic liquids (ILs) are a promising class of materials because of their unique properties such as high electrochemical stability window and intrinsic conductive nature, which are desirable in the development of high-performance electrolytes for energy storage applications. However, the strong Coulombic interactions between cation and anion, which contributes to the high viscosity of the ILs, are the main bottleneck in their applications as electrolytes. Weakly coordinated anions-based ILs are a class of electrolytes with high degree of charge delocalization, which leads to weak ionic interactions and improves the ionic transport. Here, we have performed molecular dynamics simulations and density functional theory calculations of imidazolium and ammonium-based ionic liquids in different Na  mole fractions comprising the weakly coordinated fluoroalkoxyaluminate anion ([Al(Ohfip)4]−). The results have shown that the 0.8-scaled OPLS-AA based force field predicted the transport properties of neat systems with good accuracy. The Na -[anion] pair structural and lifetime analysis suggest that the fluoroalkoxyaluminate promotes lower lifetimes and facilitates the mobility of Na  in these systems. Although the cations provided similar transport and structural results for Na , the theoretical electrochemical stability windows of the ammonium-derived ILs exhibited values above 5.0 eV, which indicates good performance for energy storage applications. https://lnkd.in/dnCFR_Pk

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