Use Of Metals Research Articles

Mining of primary raw materials as the critical foundation of 'sustainable' metals: a wicked problem for technology innovation clusters.

A transition to a more sustainable human-nature system is inextricably linked to raw materials production, if economic growth is to be maintained or increased by the emergence of new, energy- and metal-hungry technology innovation clusters. The dependence on mined raw materials is a wicked problem for societies vulnerable to negative ecological impacts and for global power bases wanting to secure access to an increasing array of feedstocks. We interrogate the issue of what constitutes a sustainable metal from a triple perspective: (i) the characteristics of ore deposits and the primary extractive operations that supply critical raw materials; (ii) the impediments for complex and interacting supply chains to maintain critical (and other) metals in use; and (iii) the lack of transparency in supply chains that makes it challenging for customers to avoid resources that have been produced by unsustainable and poor practices. We examine existing and emerging structures for resource management to explain the limits to the circular economy and what constitutes a meaningful systemic structure for primary production by responsible mining. We call for the inclusion of a standardized statement of the 'natural capital' embodied in R&D for technological materials as a means to create transparency about what constitutes a sustainable metal.This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

Ejection of molten tin in the presence of a hydrogen plasma

One of the significant obstacles left if the development of a fusion power plant is the development of Plasma Facing Components (PFCs) that can withstand the large heat and particle flux incident on the first wall and divertor region. As solid PFCs struggle with microstructure growth, sputtering and melting, liquid metals have been a popular potential replacement. Liquid metal's use as a PFC has been increasing due to its ability to self-repair damage as well as pump lost fuel and waste particles to create a low recycling edge. Currently, tin, lithium and lithium eutectics are the commonly considered liquid metals for use as a fusion PFC. It is therefore important to research the Plasma Material Interaction (PMI) between a hydrogen plasma and the liquid metal PFC candidates. This work, conducted at the Center for Plasma Material Interaction (CPMI), investigated how a molten tin surface reacts when exposed to a hydrogen plasma, building off observations by ASML of particles being ejected from a molten tin surface in the presence of a hydrogen plasma. With the ejection of tin affecting ASML's systems as well, since ejected tin can travel around their systems and cause contamination of equipment or wafers that can be destructive to the lithography process. So, for this work, molten tin was exposed to a hydrogen plasma, of varying electron densities and temperatures, and any ejected particles were collected on a witness plate to determine the particle sizes, angular distribution and mass flux. This work found the ejected tin particles range in size from 10′s ofnms to 10′s of microns and that the mass flux of tin from the molten surface is in the 10′s of mgm2*s, increasing with increased atomic hydrogen flux to the molten tin surface. Showing macroscopic amounts of molten tin are ejected in the presence of a hydrogen plasma, therefore showing tin may not be a suitable fusion PFC material.

Preparation and application of a Cu-doped antimony electrode to improve the performance of pH measurement in seawater.

Antimony-based electrodes are widely used in various fields for pH detection due to their low cost. However, their application in the marine environment is significantly hampered by the significant potential drift observed in seawater pH measurements. This study focuses on enhancing the stability of a pure antimony electrode by doping various amounts of copper without compromising its pH response. A series of electrochemical tests demonstrated that the fabricated alloy electrodes exhibited excellent pH response characteristics, including sensitivity, ion selectivity, response time, reversibility, and temperature coefficients. Moreover, the alloy electrodes were more resistant to corrosion than the pure antimony electrode, thereby guaranteeing the stability. Notably, the alloy electrodes containing 63 at% and 70 at% antimony exhibited superior electrochemical characteristics. The surface analysis elucidated that the alloy electrode had reduced oxidation, surface cracks and antimony peeling compared to the pure antimony electrode. Furthermore, the prepared alloy electrodes exhibited excellent pH response and stability in simulated high-salinity seawater and real seawater. The above results highlight that doping cheap copper into antimony can improve the electrode stability by enhancing the corrosion resistance and slowing down the oxidation rate, thus enabling reliable long-time operation in a relatively stable state. These findings provide experimental support for developing novel pH electrodes based on non-noble metals for use in challenging environments such as seawater.

MOF/TiO2 erythrocyte-like heterostructures decorated by noble metals for use in hydrogen photogeneration and pollutant photodegradation

Various heterostructures formed by hydrolysis of MOFs for photogeneration of hydrogen and photodegradation of pollutants.

Sustainable recycling technologies for thermoplastic polymers and their composites: A review of the state of the art

AbstractThis review article discusses the environmental and economic effects of recycling, as well as sustainable thermoplastic polymer recycling technologies. Several researchers have utilized recycled thermoplastics as matrices in the production of a variety of natural and synthetic‐based composites, which is also the focus of this study. All of the industries (food and packaging, construction and building, transportation, and indoor usage) where recycled thermoplastics have a large market share (food and packaging, construction and building, transportation, and indoor usage) are covered in this review. The desirable properties of thermoplastic polymers, such as corrosion resistance, low density, and user‐friendliness, have caused plastic production to surpass aluminum and other metals in use over the past 60 years. Furthermore, recycling is one of the most important measures available to mitigate these effects and is one of the most dynamic segments of the plastics industry at present. Increased landfilling and incineration of plastics have a negative impact on the ecosystem, and the continued increase in the production of virgin fossil plastic also has a negative impact on the environment. Consequently, this continuous production could lead to the depletion of fossil fuel resources, an increase in environmental emissions during processing, and eventual incineration. Increasing numbers of nations are adopting the circular economy concept in an effort to avoid all of these problems. This concept emphasizes the reuse of products and resources, as well as the recycling of materials according to the waste hierarchy, rather than their cremation or disposal in the environment.

Advances in the Key Metal‐Based Catalysts for Efficient Electrochemical Conversion of CO2

AbstractThe electrochemical reduction process is one of the most promising approaches to both efficiently remove the important greenhouse gas CO2 and convert it to chemical products of high value. However, in addition to the configuration of electrochemical cells, electrocatalysts are main factors affecting key performances in electrochemical CO2 reduction reactions. Recently, studies have been conducted to investigate the roles of metal‐based electrocatalysts and improve their performances through alloying, oxidization, and microstructural modulations. This review comprehensively discusses and analyzes the developments made in such metal‐based electrocatalyst studies and presents the advancements of important metals for use in electrochemical CO2 reduction processes. The relationships between the electrodes' microstructure, chemistry, and efficiency in CO2 conversion are also compared and discussed.

Conductive Polymer Enabled Biostable Liquid Metal Electrodes for Bioelectronic Applications.

Gallium (Ga)-based liquid metal materials have emerged as a promising material platform for soft bioelectronics. Unfortunately, Ga has limited biostability and electrochemical performance under physiological conditions, which can hinder the implementation of its use in bioelectronic devices. Here, an effective conductive polymer deposition strategy on the liquid metal surface to improve the biostability and electrochemical performance of Ga-based liquid metals for use under physiological conditions is demonstrated. The conductive polymer [poly(3,4-ethylene dioxythiophene):tetrafluoroborate]-modified liquid metal surface significantly outperforms the liquid metal.based electrode in mechanical, biological, and electrochemical studies. In vivo action potential recordings in behaving nonhuman primate and invertebrate models demonstrate the feasibility of using liquid metal electrodes for high-performance neural recording applications. This is the first demonstration of single-unit neural recording using Ga-based liquid metal bioelectronic devices to date. The results determine that the electrochemical deposition of conductive polymer over liquid metal can improve the material properties of liquid metal electrodes for use under physiological conditions and open numerous design opportunities for next-generation liquid metal-based bioelectronics.

Toxic Metal Species and 'Endogenous' Metalloproteins at the Blood-Organ Interface: Analytical and Bioinorganic Aspects.

Globally, human exposure to environmental pollutants causes an estimated 9 million deaths per year and it could also be implicated in the etiology of diseases that do not appear to have a genetic origin. Accordingly, there is a need to gain information about the biomolecular mechanisms that causally link exposure to inorganic environmental pollutants with distinct adverse health effects. Although the analysis of blood plasma and red blood cell (RBC) cytosol can provide important biochemical information about these mechanisms, the inherent complexity of these biological matrices can make this a difficult task. In this perspective, we will examine the use of metalloentities that are present in plasma and RBC cytosol as potential exposure biomarkers to assess human exposure to inorganic pollutants. Our primary objective is to explore the principal bioinorganic processes that contribute to increased or decreased metalloprotein concentrations in plasma and/or RBC cytosol. Furthermore, we will also identify metabolites which can form in the bloodstream and contain essential as well as toxic metals for use as exposure biomarkers. While the latter metal species represent useful biomarkers for short-term exposure, endogenous plasma metalloproteins represent indicators to assess the long-term exposure of an individual to inorganic pollutants. Based on these considerations, the quantification of metalloentities in blood plasma and/or RBC cytosol is identified as a feasible research avenue to better understand the adverse health effects that are associated with chronic exposure of various human populations to inorganic pollutants. Exposure to these pollutants will likely increase as a consequence of technological advances, including the fast-growing applications of metal-based engineering nanomaterials.

Nickel-decorated single vacancy phosphorene – A favourable candidate for hydrogen storage

This work studies the effect of nickel decoration on the hydrogen adsorption properties of single vacancy (SV) defective phosphorene. First principles simulations of Ni decoration show that the SV defective surfaces relax to a doped-like structure with the Ni atom in the place of the vacant phosphorus atom. The functionalised surface shows excess negative charge on neighbouring P atoms, making it suitable for sensing purposes. Additionally, the chemical activity of Ni is reduced due to strong bond formation with phosphorus. Both Ni-decorated SV phosphorene systems have H2 adsorption energies more than 3 times than that of defective phosphorene, with values between −0.594 eV and −0.6 eV. The adsorption mechanism of H2 is a two-fold process involving a small charge transfer from the surface P atoms and weak dipole-dipole interactions between the H2 molecule and the Ni atom, as the reduced chemical activity of Ni prevents bond formation with H2. The results demonstrate Ni-decorated SV Phosphorene as a promising candidate for Hydrogen storage and gas sensing applications. Further, decoration on defective phosphorene surfaces can be regarded as a method to control the chemical activity of transition metals for use in applications such as catalysis.

Ultrahigh tribocorrosion resistance of metals enabled by nano-layering

Tribocorrosion damage on metal surfaces imposes a great challenge to their reliable long-term performance in corrosive environment. In the present work, we showed that nanostructured metallic multilayers (NMMs) exhibited ultrahigh tribocorrosion resistance owing to abundant interfaces and nanoscale chemical modulation that effectively restricted plastic deformation, reduced micro-galvanic corrosion and surface reactivity. Specifically, the tribocorrosion behaviors of equal-spaced Al/X (X = Ti, Mg and Cu) NMMs with ~ 3 nm individual layer thickness were studied in 0.6 M NaCl aqueous solution under room temperature. Nanomechanical and electrochemical measurements were coupled with advanced material characterization tools to study the effects of constituting materials on the deformation and degradation mechanisms. It was found that while corrosion dominated in Al/Mg and Al/Cu NMMs, severe plastic deformation dominated in Al/Ti during tribocorrosion due to sustained surface passivity. A finite element (FE) based computational model was developed and validated to quantify the tribocorrosion behavior of all NMMs, which showed accelerated material loss at layer interfaces as well as wear track edge resulting from the synergistic effects of wear and corrosion. Finally, density functional theory (DFT) calculations were carried out to uncover the origin of corrosion resistance in NMM. It was found that via nanolayering, the surface work function of Al was increased while Cl adatoms adsorb less strongly than that on pure Al, thus reducing the surface reactivity and pitting susceptibility. The combined experimental and computational study provides a guideline for future material selection and design of multilayered and multi-phase metals for use under extreme environment.

Recent Advances in Metal Catalyst Design for CO2 Hydroboration to C1 Derivatives

The use of CO2 as a C1 building block for chemical synthesis is receiving growing attention, due to the potential of this simple molecule as an abundant and cheap renewable feedstock. Among the possible reductants used in the literature to bring about CO2 reduction to C1 derivatives, hydroboranes have found various applications, in the presence of suitable homogenous catalysts. The current minireview article summarizes the main results obtained since 2016 in the synthetic design of main group, first and second row transition metals for use as catalysts for CO2 hydroboration.

Multi-Component Composite Oxides for Superior Oxygen Evolution Reaction Performance

As a part of the effort for realize clean and renewable energy, substantial attentions are currently being paid to hydrogen generation. Of great interest is the electrocatalyst water splitting, one of the most effective ways to produce hydrogen. However, the hydrogen generation efficiency is still less than desirable due to the slow anodic oxygen evolution reaction (OER) due to primarily there are four electrons involved in the OER. Many multi-metal oxides have therefore been intensively investigated. In the paper, we report various novel oxide systems, each consisting of multiple metals for use as high performance OER electrocatalysts. The oxides were synthesized using a facile wet chemical method. The multi-metal oxides obtained include perovskite La(Mn1-xMx)O3, spinel (Fe,Co,M)3O4, and Fe5V15-xMxO39(OH)9 .9H2O, where M represents multiple metals. The material characteristics were examined using X-ray Diffractometry (XRD), scanning electron microscopy (SEM), tunneling electron microscopy (TEM), and X-ray photoelectron spectrometer (XPS). Electrochemical properties were evaluated using Multi AUTOLAB M204. Leaner sweep voltammetry (LSV) was carried out in at 5 mV/s within a potential window of 0 to 0.8 V. Stability test was carried out at 100 mV/s for 3000 CV cycles within a potential window of 0 to 0.8V. Excellent catalytic performance is demonstrated.

Вплив наночастинок СеО2 на проростання насіння та синтез фенолів у проростках ялини європейської

Modern technologies make it possible to obtain nanoparticles of biogenic metals for use as an additional source of micronutrient for plants. However, the complexity of mass application of nanosized metal particles and their oxides is due to the significant differences in physicochemical properties of nanocrystalline structures which are dependent on production technology, nanoparticle size, surface charge (-potential), and stabilization methods. The biocompatibility and nature of nanoparticles has an impact on living organisms. Regarding the effectiveness and feasibility of using cerium dioxide nanoparticles in crop practice, there is no definitive conclusion. Due to difficulty in the preparation of planting material for seedlings of conifers, the study of the effect of nanocrystalline cerium dioxide on plants is not well researched. The aim of our research was to study the effect of nanocrystalline cerium dioxide solution on the germination of spruce seeds and then to evaluate its effect on the synthesis of phenols as components of the antioxidant system within seedlings. The research used methods for determining the germination energy and seed similarities. Other methods used in this research were determining the content of phenolic compounds, flavonoids, and phenolic antioxidants. The results showed that nanocrystalline cerium dioxide in a concentration of solution from 0.1 to 1.0 mg/mL stimulates the germination of spruce seeds. Under the influence of nanoparticles at a concentration of 0.1 mg/L in the tissues of spruce seedlings increases the content of phenolic compounds. The increase in antioxidant activity of phenols in seedling tissues while decreasing their total amount at a concentration of nanocrystalline cerium dioxide from 0.5 to 1.0 mg/L occurs when increasing the total pool of flavonoids, which are determined by high antioxidant activity. Nanocrystalline cerium dioxide is a promising material for stimulating germination energy and on the overall germination of spruce seeds.

Effect of manganese addition on thermal and electrical properties of Zr45Cu45Al10 metallic glass

The article analyzes the effect of the manganese addition on the thermal and electrical properties of the (ZrCu)90-xAl10Mnx alloy where x=0; 0.5; 1; 2. The glassy alloy ribbons were produced by arc-melting and melt spinning technique. The structure of the samples was examined by X-ray diffractometry. The thermal properties were tested by differential scanning calorimetry. Four-point method was used to measure the electrical resistance. The addition of manganese significantly increases the resistivity of the alloys, as well as increases the strain sensitivity coefficient from 2.6 to 5.1. The obtained alloys are a potential substitute for alloys based on noble metals for use as a sensitive element of strain gauges.

Experimental based numerical approach for determination of volumetric heat transfer coefficients of modified graphite foams

Graphite-based porous materials are emerging as attractive alternatives to metals for use as heat dissipation elements in thermal management applications. While having several desirable features such as high thermal conductivity and low density, graphite foam heat sinks also tend to have low permeability that can limit transport of working fluid within the component and result in inefficient heat transfer. In order to improve their heat dissipation performance, graphite foams can be modified by channels drilled in various arrangements. However, the heat transfer characteristics of such modified graphite foams are not well characterized. In order to address this problem, we report novel empirical correlations for graphite foams modified in a specific configuration where circular channels with 2 mm diameter are drilled in graphite foam along the flow direction in a staggered arrangement. Then, volumetric heat transfer coefficients between the modified graphite foam and a stream of air are obtained by using transient single-blow technique (TSBT). The transient one-dimensional local thermal nonequilibrium (LTNE) model is employed for determination of the volumetric heat transfer coefficient from experimentally obtained data. Nine different modified graphite foam samples of various L/H ratios are studied in experiments and an empirical correlation of the form Nuv = CRea for each sample is derived. Empirical correlations for three different sample lengths (L = 27 mm, 52 mm, 76 mm) at a fixed height are also developed in the form of Nuv = CRea(L/H)b . The novel empirical correlations in question are valid for the Reynolds (Re) number varying from approximately 1000 to 10000. Results show that Nuv generally increases with the increasing value of Re and L at a fixed value of H and the uncertainties associated with Re and Nuv are evaluated to be less than 1.3% and 3.6%, respectively. Consequently, we anticipate that the proposed correlations will be useful in reliable design of a new generation of electronic devices.

Exploring the impact of atomic lattice deformation on oxygen evolution reactions based on a sub-5 nm pure face-centred cubic high-entropy alloy electrocatalyst

Multimetal high-entropy alloys (HEAs) have been recognized as potential catalysts that can possibly replace the conventional metal oxides and noble metals for use in energy conversion and water splitting such as oxygen evolution reactions (OERs).

Best Practices for Derivation and Application of Thresholds for Metals Using Bioavailability-Based Approaches.

The primary goal of the present study is to provide a broad view of best practices for evaluating bioavailability models for metals for use in the protection of aquatic life. We describe the state of the science regarding 1) the evaluation and selection of ecotoxicity data, 2) the selection of bioavailability models for use in normalization, and 3) subsequent application of bioavailability models. Although many examples of normalization steps exist worldwide, a scheme is proposed to evaluate and select a model that takes account of its representativeness (water chemistry and taxonomic coverage of the ecotoxicity data set) and validation performance. Important considerations for a suitable model are the quantity of inputs needed, accuracy, and ease of use, all of which are needed to set protective values for aquatic life and to use these values to evaluate potential risks to organisms in receiving waters. Although the end results of different model application approaches may be broadly similar, the differences in these application frameworks ultimately come down to a series of trade-offs between who needs to collect the data and use the bioavailability model, the different requirements of spatial scales involved (e.g., regional vs site-specific values), and model predictiveness and protectiveness. Ultimately, understanding the limits and consequences of these trade-offs allows for selection of the most appropriate model and application framework to best provide the intended levels of aquatic life protection. Environ Toxicol Chem 2019;39:118-130. © 2019 SETAC.

Interfacial Properties for a Monolayer CrS2 Contact with Metal: A Theoretical Perspective

Limited calculations show that monolayer (ML) chromium dichalcogenide (CrS2) has a direct bandgap and valley polarization but with a smaller bandgap than ML MoS2 and with distinct piezoelectric and ferromagnetic properties. It is highly desirable to determine an appropriate metal contact for novel two‐dimensional (2D) CrS2‐based devices. By using density functional theory (DFT), the interface between ML CrS2 and commonly used metals, including s‐electron and d‐electron metals, is studied systematically by evaluating the binding energy, Schottky barrier, orbital overlap, and tunneling barrier at the interfaces. The d‐electron metals show higher binding energy with the ML CrS2 than the s‐electron metals, which is due to the different occupancy and position of the d‐band of the metals. A strong Fermi level pinning is found in the metal–CrS2 contacts. Both n‐type and quasi p‐type phenomena for CrS2 with respect to pristine CrS2 can be produced at the CrS2 contacts with the metals. The higher overlap states between the CrS2 and Ti result in a higher minimum electron density at the Schottky interface, suggesting that Ti is the best contact among the investigated metals for use in CrS2‐based devices for efficient electron injection. The DFT results provide a guideline that is invaluable for experimentally designing novel 2D CrS2 semiconductor devices.

Multiplexed profiling of RNA and protein expression signatures in individual cells using flow or mass cytometry.

Advances in single-cell analysis technologies are providing novel insights into phenotypic and functional heterogeneity within seemingly identical cell populations. RNA within single cells can be analyzed using unbiased sequencing protocols or through more targeted approaches using in situ hybridization (ISH). The proximity ligation assay for RNA (PLAYR) approach is a sensitive and high-throughput technique that relies on in situ and proximal ligation to measure at least 27 specific RNAs by flow or mass cytometry. We provide detailed instructions for combining this technique with antibody-based detection of surface/internal protein, allowing simultaneous highly multiplexed profiling of RNA and protein expression at single-cell resolution. PLAYR overcomes limitations on multiplexing seen in previous branching DNA-based RNA detection techniques by integration of a transcript-specific oligonucleotide sequence within a rolling-circle amplification (RCA). This unique transcript-associated sequence can then be detected by heavy metal (for mass cytometry)- or fluorophore (for flow cytometry)-conjugated complementary detection oligonucleotides. Included in this protocol is methodology to label oligonucleotides with lanthanide metals for use in mass cytometry. When analyzed by mass cytometry, up to 40 variables (with scope for future expansion) can be measured simultaneously. We used the described protocol to demonstrate intraclonal heterogeneity within primary cells from chronic lymphocytic leukemia patients, but it can be adapted to other primary cells or cell lines in suspension. This robust, reliable and reproducible protocol can be completed in 2-3 d and can be paused at several stages for convenience.

High thermal stability ohmic contacts to nitride semiconductors with refractory metal sidewall diffusion barrier deposited by magnetron sputtering

GaN HEMTs are generally promising candidates for RF and switching power transistors due to their high breakdown strength and the high current density giving a low on-resistance. Low-resistance ohmic contacts are needed to reduce losses and self-heating. Conventional ohmic contacts use Ti and Al with a cap to avoid oxidation of the Al layer. Alternative ohmic metals for use with nitride semiconductors are being sought using Hf or Ta, which can be annealed at lower temperatures. That have been shown, the Au-free low temperature Ta/Al ohmic contacts fabricated with the refractory sidewall diffusion barrier have the lower contact resistance and the better surface morphology after the high temperature annealing. Normally-off p-gate high voltage GaN transistor based on Ta/Al ohmic contacts with the sidewall diffusion barrier have the higher drain-source current, lower gate-source current and higher source-drain breakdown voltage.