Electrons In Metals Research Articles

Nitrogen-doped carbon dot impregnated g-C3N4/SnS2 nanocomposite as an efficient mediator and co-catalyst for enhanced photocatalytic degradation and water splitting

Noble metal electron mediators and co-catalysts have prevented further development of indirect Z-scheme systems for photocatalytic applications. Carbonaceous candidates have been one of the best alternatives to address this issue. For this purpose, in the present study, a novel nitrogen-doped carbon dot (N-DCD) impregnated g-C3N4/SnS2 heterostructure has been successfully synthesized with optimized contents of N-DCDs and SnS2 ultra-thin nanoflakes through thermal-impregnation and reflux methods. The most efficient nanocomposite containing 0.25 wt% N-DCDs and 2 wt% SnS2 exhibited methylene blue (MB) degradation rate constant of 0.032 min−1 and hydrogen (H2) production efficiency of 1622.2 μmol/g.h after 120 and 180 min visible light irradiation. The photodegradation rate constant was almost 32, 8, and 2, and H2 production efficiency was 16, 30, and 5 fold higher than g-C3N4, SnS2, and g-C3N4/2 wt% SnS2 (without N-DCDs), respectively. The photodegradation and H2 production efficiencies are enhanced by impregnated N-DCDs, which act as an electron mediator and noble metal-free co-catalyst. Through N-DCDs impregnation, the synergistic effect between SnS2 and up-conversion properties of N-DCDs was observed, resulting in the reduction of the band gap energy from 2.97 eV in g-C3N4 to 2.80 eV in the optimized ternary nanocomposite, as well as reductions in PL intensity and onset potential. The major active species throughout photocatalytic degradation reactions were superoxide and hydroxyl radicals, proposing a Z-scheme mechanism for charge transfer. The optimized ternary nanocomposite also exhibited outstanding photostability after recycling tests. This work highlighted the role of N-DCDs as a highly effective noble metal-free co-catalyst and electron mediator in photocatalytic applications. Data Availability StatementThe raw/processed data required to reproduce these findings cannot be shared at this time due to legal or ethical reasons.

Influence of Transition Metal Electron Configuration on the Structure of Metal–EDTA Complexes

The vibrational spectra of cold complexes of ethylenediaminetetraacetic acid (EDTA) with transition metal dications in vacuo show how the electronic structure of the metal provides a geometric template for interaction with the functional groups of the binding pocket. The OCO stretching modes of the carboxylate groups of EDTA serve as structural probes, informing on the spin state of the ion as well as the coordination number in the complex. The results highlight the flexibility of EDTA in accepting a large range of metal cations in its binding site.

Size-dependent heat capacity in nano-oxide crystals

Recent developments suggest that heat capacity of nano-oxides is size-dependent, since the product of bulk modulus (B) and thermal expansion coefficient (α) scales directly with isometric heat capacity Cv. Dependence of heat capacity on crystal-size Cv(d) is explored by examining Bαao where ao is the lattice parameter. Here Bαao(d)'s show maxima at 33 nm for ceria and at 14 nm for MgO and decrease with decreasing crystal-size (d) implying similar size-dependence for Cv if the Grüneisen parameter is size insensitive. Hence, the Cv (d) contradicts with metal's heat capacities which are larger in nano-grains. Contributions from grain boundaries and surfaces were posited for the difference. Besides phonons, free electrons in metals contribute to heat capacity. The absence of electronic carriers in oxides likely explains the difference.

Site‐dependent correlation strength and occupation number of 5f electrons in alpha phase plutonium metal

AbstractIn order to quantify the site‐dependent correlation strengths in terms of the quasi‐particle weights and the occupation numbers of 5f electrons in alpha phase plutonium metal with eight crystallographically nonequivalent atomic sites Pun (n = 1–8), we perform a first principles calculation by using a many‐body method merging density functional theory with dynamical mean‐field theory plus the relativistic and correlation effects. The quasi‐particle weight, the electronic spectrum function, the hybridization function, as well as the occupation number of Pu 5f electrons all suggest that Pu1 and Pu8 atoms have the most itinerant and the most localized 5f electrons, respectively, while the other atoms Pun (n = 2–7) exhibit an intermediate correlation strength. The quasi‐particle weights demonstrate that only the jj or intermediate coupling scheme is more appropriate for Pu 5f electrons in comparison with the Russel–Saunders (LS) scheme. The electronic spectrum function and the occupation analysis establish that Pu 5f electrons simultaneously have dual itinerant and localized regimes with average 5f occupation numbers of n5f between 4.8994 and 4.9628, which are mainly composed of 5f4, 5f5, and 5f6 configurations, irrespective of different atomic sites. Finally, we also estimate the so‐called quasi‐particle band structure to directly compare with angle‐resolved photoemission spectrum.

Magnetic and Electronic Properties of Edge-Modified Triangular WS2 and MoS2 Quantum Dots

The magnetic and electronic properties of zigzag-triangular WS2 and MoS2 quantum dots are investigated using density functional theory calculations. The pristine WS2 and MoS2 nanodots hold permanent spin on their edges which originates from the unpaired electrons of the transition metals at the edges. The ferromagnetic spin ordering in zigzag-triangular WS2 and MoS2 can be transformed to antiferromagnetic ordering with S = 0 and to nonmagnetic, respectively, by edge passivation with 2H. The calculations of the Curie Temperature indicate that these magnetic states are stable and withstand room temperature. The paramagnetic susceptibility of these structures significantly decreases by edge sulfuration. Moreover, it can be converted to diamagnetic susceptibility by edge passivation with 2H as found in WS2 nanodots. These structures are semiconductors with energy gaps of ~3.3 eV that decrease unexpectedly by edge passivation due to the existence of lone pairs from S atoms that give a high contribution to the low-energy molecular orbitals. With these preferable magnetic properties and controlled electronic ones, WS2 and MoS2 quantum dots are potential candidates for spintronic applications.

Electronic transport on the two state “ON–OFF” of 1,3,3-trimethylindolino-6′-nitrobenzopyrylospiran as a light-driven molecular optical switch: A first-principle study

Here, the electronic transport characteristics of the 1,3,3-trimethylindolino-6′-nitrobenzopyrylospiran were studied by using NEGF and DFT methods. By being exposed to UV or visible light, this molecule can change from its MC to SP states. The titled structure was optimized at B3LYP/6–311++G(d,p) level of theory. To obtain conductivity results, the electrons of metal and organic atoms were approached by the single-plus polarization (SZP) for single-zeta and double-plus polarization (DZP) for double zeta basis sets, respectively. We examined some factors in this study, including various molecule geometries, the type of surface materials (Platinum, gold, and silver), the switching ratio, the gap between HOMO and LUMO levels, and the transmission spectra, at different bias voltages. The outcomes show that conductivity transforms from an off-state (high resistance) to an on-state as the molecule switches from MC to SP form (low resistance).

Density-Potential Functional Theory of Electrochemical Double Layers: Calibration on the Ag(111)-KPF6 System and Parametric Analysis.

The density-potential functional theory (DPFT) of electrochemical double layer (EDL) is upgraded by adopting (generalized) gradient approximations for kinetic, exchange, and correlation functionals of metal electrons. A new numerical scheme that is more stable and converges faster is proposed to solve the DPFT model. The DPFT model is calibrated with existing differential double-layer capacitance (Cdl) data of the EDL at Ag(111)-KPF6 aqueous interface at five concentrations at room temperature. Metal electronic effects are essential to explain why the two peaks of the camel-shaped Cdl curves are almost symmetric in spite of the size difference of the hydrated cations and anions. A systematic parametric analysis is then conducted in terms of key EDL properties, including the potential of zero charge and the differential capacitance. The parametric analysis, on the one hand, elucidates how quantum mechanical behaviors of metal electrons as well as interactions between metal electrons and the electrolyte solution impact the EDL properties and, on the other hand, identifies key parameters of the DPFT model, which should be calibrated using first-principles calculations and/or advanced experiments in the future.

Polar metals taxonomy for materials classification and discovery

Over the past decade, materials that combine broken inversion symmetry with metallic conductivity have gone from a thought experiment to one of the fastest growing research topics. In 2013, the observation of the first uncontested polar transition in a metal, ${\mathrm{LiOsO}}_{3}$, inspired a surge of theoretical and experimental work on the subject, uncovering a host of materials which combine properties previously thought to be contraindicated [Shi et al., Nat. Mater. 12, 1024 (2013)]. As is often the case in a nascent field, the sudden rise in interest has been accompanied by diverse (and sometimes conflicting) terminology. Although ``ferroelectriclike'' metals are well defined in theory, i.e., materials that undergo a symmetry-lowering transition to a polar phase while exhibiting metallic electron transport, real materials find a myriad of ways to push the boundaries of this definition. Here, we review and explore the burgeoning polar metal frontier from the perspectives of theory, simulation, and experiment while introducing a unified taxonomy. The framework allows one to describe, identify, and classify polar metals; we also use it to discuss some of the fundamental tensions between theory and models of reality inherent in the terms ``ferroelectric'' and ``metals.'' In addition, we highlight shortcomings of electrostatic doping simulations in modeling different subclasses of polar metals, noting how the assumptions of this approach depart from experiment. We include a survey of known materials that combine polar symmetry with metallic conductivity, classified according to the mechanisms used to harmonize those two orders and their resulting properties. We conclude by describing opportunities for the discovery of novel polar metals by utilizing our taxonomy.

A Potential‐Based Boundary Element Implementation for Modeling Multiple Scattering from Local and Nonlocal Plasmonic Nanowires

AbstractA novel boundary element implementation that models multiple scattering of plasmonic nanowires is presented. The modeling is based on potentials and the materials constituting the wires can be local (described by the local response model) or nonlocal (described by the nonlocal hydrodynamic model). The nonlocal hydrodynamic model (HDM) provides an important approximation describing nonclassical effects associated with the collective motion of free electrons in metals. The modeling is challenging as different interface conditions are needed at a boundary which separates 1) a local medium from a local medium; 2) a local (nonlocal) medium from a nonlocal (local) medium; and 3) a nonlocal medium from a nonlocal medium. The algorithm can address constructs of arbitrary geometry and material composition within the HDM; thus, it becomes a complete numerical tool for exploration of nonlocal nanowires. Fictitious sources are imposed at the boundaries, linking the scattered fields to the imposed sources, and matching the interface conditions at the boundaries. This procedure yields a set of Boundary Integral Equations (BIEs). Then, the BIEs are numerically solved utilizing the Boundary Element Method (BEM). The results from the BEM solver are verified quantitatively and qualitatively showing good agreement in both the near‐ and the far‐field regimes.

Text-Mining to Identify Gene Sets Involved in Biocorrosion by Sulfate-Reducing Bacteria: A Semi-Automated Workflow.

A significant amount of literature is available on biocorrosion, which makes manual extraction of crucial information such as genes and proteins a laborious task. Despite the fast growth of biology related corrosion studies, there is a limited number of gene collections relating to the corrosion process (biocorrosion). Text mining offers a potential solution by automatically extracting the essential information from unstructured text. We present a text mining workflow that extracts biocorrosion associated genes/proteins in sulfate-reducing bacteria (SRB) from literature databases (e.g., PubMed and PMC). This semi-automatic workflow is built with the Named Entity Recognition (NER) method and Convolutional Neural Network (CNN) model. With PubMed and PMCID as inputs, the workflow identified 227 genes belonging to several Desulfovibrio species. To validate their functions, Gene Ontology (GO) enrichment and biological network analysis was performed using UniprotKB and STRING-DB, respectively. The GO analysis showed that metal ion binding, sulfur binding, and electron transport were among the principal molecular functions. Furthermore, the biological network analysis generated three interlinked clusters containing genes involved in metal ion binding, cellular respiration, and electron transfer, which suggests the involvement of the extracted gene set in biocorrosion. Finally, the dataset was validated through manual curation, yielding a similar set of genes as our workflow; among these, hysB and hydA, and sat and dsrB were identified as the metal ion binding and sulfur metabolism genes, respectively. The identified genes were mapped with the pangenome of 63 SRB genomes that yielded the distribution of these genes across 63 SRB based on the amino acid sequence similarity and were further categorized as core and accessory gene families. SRB's role in biocorrosion involves the transfer of electrons from the metal surface via a hydrogen medium to the sulfate reduction pathway. Therefore, genes encoding hydrogenases and cytochromes might be participating in removing hydrogen from the metals through electron transfer. Moreover, the production of corrosive sulfide from the sulfur metabolism indirectly contributes to the localized pitting of the metals. After the corroboration of text mining results with SRB biocorrosion mechanisms, we suggest that the text mining framework could be utilized for genes/proteins extraction and significantly reduce the manual curation time.

"d-electron interactions" induced CoV2O6-Fe-NF for efficient oxygen evolution reaction.

The investigation of cost-effective, highly efficient, and environmentally friendly non-noble-metal-based electrocatalysts is imperative for oxygen evolution reactions (OER). Herein, CoV2O6 grown on nickel foam (NF) was selected as the fundamental material, and Fe2+ is introduced through a simple Fe3+ immersion treatment to synthesize CoV2O6-Fe-NF. Fe2+ is transformed into high oxidation state Fe(2+δ)+ due to interactions between the 3d electrons of transition metals. In situ Raman spectroscopy analysis reveals the specific process of OER in the presence of Fe(2+δ)+. Being in a higher oxidation state, Fe(2+δ)+ provides more active sites, which is beneficial for the reaction between water molecules and the reactive sites of the electrocatalyst, ultimately enhancing the accelerated OER process. CoV2O6-Fe-NF exhibited an overpotential of only 298 mV at 100 mA cm-2 in 1 M KOH electrolyte, which is lower than that of CoV2O6-NF (348 mV), as well as the comparative samples: Fe-NF (390 mV) and NF (570 mV). The exploration of high performance, triggered synergistically by the cooperative effect of transition metal 3d electrons, provides insights into the design of transition metal electrocatalysts for highly efficient OER.

From sandwich complexes to dendrimers: journey toward applications to sensing, molecular electronics, materials science, and biomedicine.

This review links various areas of inorganic chemistry around the themes developed by our research group during the last four decades. It is firstly based on the electronic structure of iron sandwich complexes, showing how the metal electron count dictates their reactivities, with various applications (via C-H activation, C-C bond formation) as reducing and oxidizing agents, redox and electrocatalysts and precursors of dendrimers and catalyst templates through bursting reactions. Various electron-transfer processes and consequences are explored, including the influence of the redox state on the acidity of robust ligands and the possibility to iterate in situ C-H activation and C-C bond formation to build arene-cored dendrimers. Examples of how these dendrimers are functionalized are illustrated using the cross olefin metathesis reactions, with application to the synthesis of soft nanomaterials and biomaterials. Mixed and average valence complexes give rise to remarkable subsequent organometallic reactions, including the salt influence on these reactions. The stereo-electronic aspect of these mixed valencies is pointed out in star-shaped multi-ferrocenes with a frustration effect and other multi-organoiron systems, with the perspective of understanding electron-transfer processes among dendrimer redox sites involving electrostatic effects and application to redox sensing and polymer metallocene batteries. Dendritic redox sensing is summarized for biologically relevant anions such as ATP2- with supramolecular exoreceptor interactions at the dendrimer periphery in parallel with the seminal work on metallocene-derived endoreceptors by Beer's group. This aspect includes the design of the first metallodendrimers that have applications in both redox sensing and micellar catalysis with nanoparticles. These properties provide the opportunity to summarize the biomedical (mostly anticancer) applications of ferrocenes, dendrimers and dendritic ferrocenes in biomedicine (in particular the contribution from our group, but not only). Finally, the use of dendrimers as templates for catalysis is illustrated with numerous reactions including C-C bond formation, click reactions and H2 production reactions.

Rolled metal electron plasma treatment for automotive hardware cold upsetting

One of the most important objectives of the modern car production development is to improve the quality of metal products and parts made from it, increase their efficiency, reliability, service life, bringing these indicators to the level of the world standards, ensuring the competitiveness of domestic products at the foreign market. The structural safety of motor vehicles is largely determined by the operational reliability of the constituent elements. Car fasteners made of high-carbon and alloy wire, including hardware items, are among the critical and widely used parts in mechanical engineering. The most common and progressive method of their manufacture is the cold upsetting from rolled bar material. The bar material surface condition has a significant impact on its quality. Hot rolled products from metallurgical plants are typically delivered to the processing facilities covered with scale and rust. To improve the surface quality of semifinished metallurgical products for rerolling at the stage of wire preparation for drawing, it is subjected to continuous mechanical or chemical cleaning. Traditionally, the technology of surface scale removing by etching is used in production. This method of scale removal provides a high level of cleaning, but there are problems with the disposal of spent acid solutions, reducing the steel ductility. Mechanical methods of scale removal have been widely introduced recently, although the use of mechanical scale removal devices also does not completely solve the problem. The paper considers the possibility of using advanced electron plasma treatment technologies for these purposes and the influence of traditional methods and this scale removing method from the rolled steel surface on the quality of metal preparation for upsetting.

PENILAIAN POSTUR TUBUH PEKERJA HPES PLATING DI PT. ABC MENGGUNAKAN METODE OWAS

PT. ABC is a company engaged in the production and management of metal and plastic electron components, namely Presicion Metal Stamping and Forming, Precision Cold Forged Treatment and Surface Treatment. One of the departments in this company is the HPES Plating department. In production line activities at HPES Plating, there is work that is predominantly done in the work posture, namely standing, sitting, and bending as well as manual lifting handling activities. This study aims to assess the body posture scores of workers in the HPES Plating department of PT. ABC which has the potential for musculoskeletal disorders using the OWAS method. The results of the posture assessment at the time of incoming product inspection activities were 1, receiving system activities were 1, product transfers were 1, product lifting was 3, jigging activities were 1, product preparation was 2, loading activities were 1, VMI inspections were 1, product packing was 3, OQA inspections were 1, and shipment activities were 2. So that immediate improvements are needed for the work posture of product lifting, product preparation, product packing and shipment.

Nanowire-assisted freestanding liquid metal thin-film patterns for highly stretchable electrodes on 3D surfaces

Stretchable electronics is playing an integral role in fields such as wearable electronics and soft robots. Among soft conductive materials, liquid metal is drawing intense attention as an electrode material due to its liquid nature at room temperature. However, the merits of liquid metal conductor are limited by the presence of substrates or enclosed microchannels from physical disturbances by the underlying substrate when applying it to 3D surface and modifying complex circuit. To overcome this limitation, we develop freestanding patterned liquid metal thin-film conductor (FS-GaIn). FS-GaIn was achieved by introducing metal nanowires to liquid metal and subsequent sequential selective laser processing and etching of directly patterned traces. FS-GaIn can be applied directly to nonflat surface without substrates. When incorporated into electrical circuits, FS-GaIn shows high electrical conductivity, stretchability, and stability. The concept of freestanding liquid metal can open a functionality to the conventional liquid metal electronics.

Colloquium : Planckian dissipation in metals

Relaxational processes for conduction electrons in metals come with characteristic temperature dependences; classic examples at low temperatures are the $1/{T}^{2}$ law for the relaxation time in a Fermi liquid, and the Bloch $1/{T}^{5}$ law for electron-phonon scattering. The strange metal phase of cuprate superconductors is governed instead by the Planckian time, which is given in terms of fundamental constants only. This Colloquium discusses the concept of such a fundamental timescale and the degree to which it provides a lower bound for relaxation times, and illustrates these ideas with examples from conventional and unconventional metals.

OpenSANS: A Semi-Analytical solver for Nonlocal plasmonicS

Prompted by the renewed interest the past decade in the hydrodynamic model for the description of nanoplasmonic systems, we present OpenSANS, a MATLAB toolbox for the simulation of canonical (that is, standalone spherical and cylindrical) nanoparticles and planar stratified structures whose critical dimensions are of mere nanometres. The method comprises of a generalisation of Mie theory to properly address the hydrodynamic motion of free electrons in metals and a compact S matrix formulation for the efficient treatment of multiple layers. The toolbox is built in a modular manner; each part (routine) has its own important functionality and can be used independently from the others. Our primary goal is the presentation of a highly efficient and accessible solver for the nanoplasmonics community. This is achieved by the very semi-analyticity of the chosen method and by powerful vectorisation techniques optimised in a very popular environment, MATLAB. Program summaryProgram Title: OpenSANSCPC Library link to program files:https://doi.org/10.17632/hmk224xngb.1Code Ocean capsule:https://codeocean.com/capsule/2246190Licensing provisions: GPLv3Programming language: MATLAB R2018b and newer.Supplementary material: See Appendix A.Nature of problem: Solve the scattering problem from multilayered, dielectric, local or nonlocal metallic nanoparticles, excited by a plane wave and placed in a local (dielectric or metallic) background.Solution method: Mie theory, appropriately extended to incorporate nonlocal effects (longitudinal waves) as predicted by the Hard Wall-Hydrodynamic Model, combined with S matrix theory for efficient handling of the multilayered structure.

Development and coupling test of active spacecraft potential control – Next generation (ASPOC-NG)

The active spacecraft potential control (ASPOC) system developed in the 1990s emits positive ions to neutralise the spacecraft potential, such as used in several missions like Geotail, Equator-S, Cluster, Doublestar and MMS. With the experience gained, the next generation of the active spacecraft potential control (ASPOC-NG) instrument has been developed over the last three years. Thereby, three emission technologies were tested including Liquid Metal Ion Source (LMIS), Liquid Metal Electron Source (LMES) and Solid Metal Electron Source (SMES). The development of the emitter module by FOTEC and the corresponding electronics control unit by IWF is presented. Optimisations were carried out with the focus on the reduction of mass and power consumption to comply with the requirements of future scientific missions. Coupling tests of the modules and the electronics control unit were performed including range, accuracy and lifetime tests. Both ASPOC-NG instruments for positive and negative charge compensation and their performance values show excellent results.

High-Performance Room-Temperature NO2 Gas Sensor Based on Au-Loaded SnO2 Nanowires under UV Light Activation.

Optical excitation is widely acknowledged as one of the most effective means of balancing sensor responses and response/recovery properties at room temperature (RT, 25 °C). Moreover, noble metals have been proven to be suitable as photosensitizers for optical excitation. Localized surface plasmon resonance (LSPR) determines the liberalization of quasi-free electrons in noble metals under light irradiation, and numerous injected electrons in semiconductors will greatly promote the generation of chemisorbed oxygen, thus elevating the sensor response. In this study, pure SnO2 and Au/SnO2 nanowires (NWs) were successfully synthesized through the electrospinning method and validated using XRD, EDS, HRTEM, and XPS. Although a Schottky barrier led to a much higher initial resistance of the Au/SnO2 composite compared with pure SnO2 at RT in the dark, the photoinduced resistance of the Au/SnO2 composite became lower than that of pure SnO2 under UV irradiation with the same intensity, which confirmed the effect of LSPR. Furthermore, when used as sensing materials, a detailed comparison between the sensing properties of pure SnO2 and Au/SnO2 composite toward NO2 in the dark and under UV irradiation highlighted the crucial role of the LSPR effects. In particular, the response of Au/SnO2 NWs toward 5 ppm NO2 could reach 65 at RT under UV irradiation, and the response/recovery time was only 82/42 s, which far exceeded those under Au modification-only or optical excitation-only. Finally, the gas-sensing mechanism corresponding to the change in sensor performance in each case was systematically proposed.

Entanglement Negativity and Concurrence in Some Low-Dimensional Spin Systems.

The influence of magnon bands on entanglement in the antiferromagnetic XXZ model on a triangular lattice, which models the bilayer structure consisting of an antiferromagnetic insulator and normal metal, is investigated. This effect was studied in ferromagnetic as well as antiferromagnetic triangular lattices. Quantum entanglement measures given by the entanglement negativity have been studied, where a magnon current is induced in the antiferromagnet due to interfacial exchange coupling between localized spins in the antiferromagnet and itinerant electrons in a normal metal. Moreover, quantum correlations in other frustrated models, namely the metal-insulation antiferromagnetic bilayer model and the Heisenberg model with biquadratic and bicubic interactions, are analyzed.