Ga Metal Research Articles

Bubble-Propelled Janus Gallium/Zinc Micromotors for the Active Treatment of Bacterial Infections.

We report a bubble-propelled Janus gallium/zinc (Ga/Zn) micromotor with good biocompatibility and biodegradability for active target treatment of bacteria. The Janus Ga/Zn micromotors are fabricated by asymmetrically coating liquid metal Ga on Zn microparticles and display self-propulsion in simulated gastroenteric acid (pH 0.5) at a speed of up to 383 μm s-1 , propelled by hydrogen bubbles generated by the zinc-acid reaction. This motion of Ga/Zn micromotors is enhanced by the Ga-Zn galvanic effect. The GaIII cations produced from the degradation of Ga/Zn micromotors serve as a built-in antibiotic agent. The movement improves the diffusion of GaIII and results in a significant increase of the antibacterial efficiency against H. pylori, compared with passive Ga microparticles. Such Ga/Zn micromotors combine the self-propulsion, good biocompatibility and biodegradability, and Ga-based antibacterial properties, providing a proof of concept for the active treatment of bacterial infections.

Bubble‐Propelled Janus Gallium/Zinc Micromotors for the Active Treatment of Bacterial Infections

AbstractWe report a bubble‐propelled Janus gallium/zinc (Ga/Zn) micromotor with good biocompatibility and biodegradability for active target treatment of bacteria. The Janus Ga/Zn micromotors are fabricated by asymmetrically coating liquid metal Ga on Zn microparticles and display self‐propulsion in simulated gastroenteric acid (pH 0.5) at a speed of up to 383 μm s−1, propelled by hydrogen bubbles generated by the zinc–acid reaction. This motion of Ga/Zn micromotors is enhanced by the Ga–Zn galvanic effect. The GaIII cations produced from the degradation of Ga/Zn micromotors serve as a built‐in antibiotic agent. The movement improves the diffusion of GaIII and results in a significant increase of the antibacterial efficiency against H. pylori, compared with passive Ga microparticles. Such Ga/Zn micromotors combine the self‐propulsion, good biocompatibility and biodegradability, and Ga‐based antibacterial properties, providing a proof of concept for the active treatment of bacterial infections.

Acenaphthylene-Bis(arylamide) Complexes of Aluminum and Gallium in the Polymerization of Lactide

The catalytic activity of aluminum and gallium compounds with the noninnocent acenaphthene-1,2-diimine ligand dpp-bian (=1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) in the ring-opening polymerization of lactic acid lactides is studied. It is shown that in this process the homobimetallic compounds of aluminum and gallium of the composition [(dpp-bian)Mt]2 exhibit a low activity and do not provide control over the molecular weight characteristics of the resulting polymers. On the contrary, in the presence of the (dpp-bian)Ga(OCH2CH2NMe2) metal complex the polymerization of lactide proceeds in a controlled manner and the reaction is of the first order with respect to the monomer. The aluminum analog of the mononuclear gallium alkoxide complex is catalytically inactive in the polymerization of lactide.

Room temperature rectification in tapered-channel thermal diodes through nanoscale confinement-induced liquid–solid phase change

Designing thermal diodes is attracting a considerable amount of interest recently due to the wide range of applications and potentially high impact in the transportation and energy industries. Advances in nanoscale synthesis and characterization are opening new avenues for design using atomic-level tools to take advantage of materials properties in confined volumes. In this paper, we demonstrate using advanced modeling and simulation the rectification properties of tapered-channel thermal diodes relying on asymmetric heat flow brought about by thermal conductivity differences between the liquid and solid phases of suitably selected phase-change materials (PCM). Our prototypical design considers Ga as PCM and anodized alumina as the structural material. First, we use a thresholding scheme to solve a Stefan problem in the device channel to study the interface shape and the hysteresis of the phase transformation when the temperature gradient is switched. We then carry out finite-element simulations to study the effect of several geometric parameters on diode efficiency, such as channel length as aspect ratio. Our analysis establishes physical limits on rectification efficiencies and point to design improvements using several materials to assess the potential of these devices as viable thermal diodes. Finally, we demonstrate the viability of proof-of-concept device fabrication by using a non-conformal atomic layer deposition process in anodic alumina membranes infiltrated with Ga metal.

Mechanochemical synthesis of intermetallic compounds in the system gallium – ruthenium

The interaction of a solid inert metal Ru with liquid active metal Ga during mechanical activation in a high-energy planetary ball mill was studied using the X-ray diffraction and the high resolution scanning electron microscopy with energy dispersive X-ray microanalyses. This paper considers mechanical activation effects on formation of intermetallic compounds GaxRuy and their solubility in concentrated acids. Gallium is a surface-active substance with respect to Ruthenium. Under intensive mechanical treatment, liquid Gallium penetrates into grain boundaries of polycrystalline Ruthenium particles and sharply reduces their strength. Because of severe mechanical deformation, an intensive increase of contact surface between solid and liquid metals observed, which a place of rapid formation of intermetallic compounds. This processing leads to high reactive products of mechanical activation of Ga + Ru. Their interaction with a mixed concentrated hydrochloric and nitric acid allows Ruthenium (~37%) to pass into an acidic solution, forming complex compounds of the HxRuCly type (H2RuCl6).

Disentangling the enhanced catalytic activity on Ga modified Ru surfaces for sodium borohydride electrooxidation

Herein, multi walled carbon nanotube (MWCNT) supported RuGa nanocatalysts (RuGa/MWCNTs) are synthesized at varying atomic molar ratio via sodium borohydride (SBH) reduction method toward SBH electrooxidation (SBHE) and SBH hydrolysis (RSBH). From the X-ray diffraction (XRD) results, Ru and Ga metals are found to be in the alloy form and the average crystal size is determined as 2.77 nm. The distribution of RuGa particles on MWCNT is confirmed using SEM-EDX. These nanocatalysts were employed for RSBH and further measurements were performed to investigate their SBHE activity. For RSBH for RuGa/MWCNT nanocatalysts, one could note that Ga addition to Ru enhanced the initial rate, H2 generation rate, and turnover frequency values and Ru99Ga1/MWCNT has the highest initial rate, H2 generation rate, and turnover frequency value. According to the cyclic voltammetry (CV) results of the prepared RuGa/MWCNT nanocatalysts, Ru99Ga1/MWCNT show the highest electrocatalytic activity for SBHE and this result is in line with the results of electrochemical impedance spectroscopy (EIS). In addition, chronoamperometric curves indicate that Ru99Ga1/MWCNT possesses long term stability compared to these of other nanocatalysts. Catalytic RSBH results of Ru99Ga1/MWCNT show that this nanocatalyst is more active than others. As a result, it is clear that RuGa/MWCNT is a promising nanocatalyst for fuel cells.

Geochemistry of heavy metal-contaminated sediments from the Four River inlets of Dongting lake, China.

The concentrations of major and trace elements in the sediments from the Four River inlets of Dongting Lake were analysed. The results show that the element compositions of the Four River inlet sediments are different, among which higher amounts of Al2O3, Fe2O3, MnO, Cs, Rb, Th, U, Y, and REE are found, while MgO, CaO, Na2O, and Sr are more depleted in the sediments from the Xiangjiang and Zijiang inlets than in the sediments from the Yuanjiang and Lishui inlets. The Xiangjiang inlet sediments are distinctly higher enriched (EF > 5.0) in heavy metals Bi, Cd, Mn, Cu, Pb, and Zn, while the other river sediments are moderately enriched (EF > 2.0) in these heavy metals. These geochemical differences are resulted from the source lithology, chemical weathering, hydrological sorting, and anthropogenic processes taking place in the watersheds. The principal component analysis and the geochemical vertical profiles suggest that the trace metals Ba, Mo, V, Cr, Co, Ni, Cs, Rb, Sc, Th, U, Ga, Ge, Zr, Hf, Ta, Nb, and REE are of terrigenous sources. The heavy metals including Bi, Cd, Mn, Cu, Pb, and Zn in the sediments can include those contributed by anthropogenic processes, such as mining and smelting of Pb-Zn ores. Therefore, presenting a scheme for the geochemical backgrounds of the watershed is recommended here for future assessment of the heavy metal contamination in sediments of the watershed.

Study on Direct Writing of Gallium Metal for the Flexible Sensor

There is an urgent need for a simple and effective method to manufacture flexible sensors composed of liquid metal. Gallium (Ga) metal has become an ideal flexible conductive material due to its high conductivity, low melting point, and high flow characteristics. In this paper, liquid Ga metal is directly written on the polyvinyl alcohol (PVA) film through the driving mode of piston extrusion; then, the Ga metal wire is transferred and sealed with silica gel. The advantages of piston mode are studied, and the direct writing parameters of the liquid Ga metal, including extrusion speed, nozzle height, printing speed, and nozzle inner diameter, are systematically optimized. The flexible sensor based on the sealed liquid Ga metal has good resilience under the external load. This work provides a specific reference for direct writing of liquid Ga metal and its sealing technology for the flexible sensor.

Complexes of In(III) with 8-hydroxyquinoline-5-sulfonate in solution: structural studies and the effect of cationic surfactants on the photophysical behaviour.

Following previous studies on the complexation in aqueous solutions of 8-hydroxyquinoline-5-sulfonate (8-HQS) with the trivalent metal ions, Al(III) and Ga(III) and various other metal ions, using multinuclear NMR, DFT calculations, UV-vis absorption and luminescence techniques, we have extended our studies on 8-HQS complexation to the trivalent metal ion In(III). The study combines the high sensitivity of luminescence techniques and the selectivity of multinuclear NMR spectroscopy with the structural details accessible through DFT calculations, and aims to obtain a complete understanding of the complexation between the In3+ metal ion and 8-HQS, and how this influences the luminescence behaviour. A full speciation study has been performed and, as has been reported for the complexes of 8-hydroxyquinoline (8-HQ), the dominant complexes of 8-HQS with In(III) show marked differences in the complexation behaviour when compared with the equivalent complexes with the other group 13 cations Al(III) and Ga(III). While all three complexes have a 1 : 3 (metal : ligand) stoichiometry, those with Al(III) and Ga(III) show a mer-geometry of the ligands around the metal centre, whereas the fac-geometry is observed for the complexes with In(III). On binding to metal ions, 8-HQS shows a marked increase in the intensity of the fluorescence emission band compared to that of the virtually non-luminescent free ligand. However, the increase for In(III) is less pronounced than with Al(III) or Ga(III). These observations have important implications for the application of the complexes in sensing, light emitting devices (e.g. OLEDs), or as electron transport layers in photovoltaics for solar energy conversion. Furthermore, surfactant complexation is known to improve the fluorescence intensity in metal complexes with 8-HQS, by inhibiting the ligand exchange, as we have reported for complexes of HQS with Al(III) and Ga(III). Accordingly, in view of the development of applications in either sensing or optoelectronics, our interest also includes the study of HQS complexes of In(III) in the presence of cationic surfactants, in comparison with previous results with Al(III) and Ga(III).

Atomic-Scale Probing of Defect-Assisted Ga Intercalation Through Graphene Using ReaxFF Molecular Dynamics Simulations

We report a joint theory and experimental investigation on the defect-mediated surface interactions of gallium (Ga) metals and trimethyl-gallium (TMGa) molecules with graphene. A combination of Raman spectra, X-ray photoelectron spectroscopy, scanning tunneling microscopy (STM) and spectroscopy reveal defects in graphene, which can act as pathways for Ga intercalation. These experimental results are connected to ReaxFF simulations, which further confirm that the Ga and TMGa adsorption on graphene is strongly impacted by the presence and size of defects. These defects catalyze the surface reactions by lowering the temperature for Ga-deposition on the surface. Moreover, multivacancy defects promote Ga intercalation through graphene by reducing the kinetic barrier while the migration through single vacancy or 585 defects is kinetically hindered. The ReaxFF results indicate that TMGa exposure can lead to defect healing by the passivation of carbon-dangling bonds by hydrocarbon and organometallic adducts, which is supported by the decreased Raman D:G ratio in Ga-intercalated graphene and by STM images. Since probing and controlling graphene defects constitutes a key step in the intercalation mechanism, this work provides an in-depth atomic scale understanding into the complex interplay between defects and precursors, thus providing an effective way to design defects for 2D metal fabrication.

Liquid–Solid Mixtures of Ga Metal Infused with Cu Microparticles and Nanoparticles for Microscale and Nanoscale Patterning of Solid Metals at Room Temperature

This paper demonstrates and characterizes a simple ink for nanopatterning of solid metallic structures under ambient conditions by taking advantage of the low melting point of gallium and its affin...

Structural and dynamic properties of short-period GaN/AlN superlattices grown by submonolayer digital epitaxy

Structural and dynamic properties of short-period GaN/AlN superlattices with the thicknesses of the constituent layers varying from two to several monolayers, grown using the method of submonolayer digital molecular beam epitaxy, are experimentally and theoretically studied. It is established that in the grown samples there are two types of periodicity. One type is formed by periodic sequence of GaN and AlN layers in the superlattice, and the second one is related with periodic interruptions in the growth of superlattice for the evaporation of excess Ga metal. The dependences of the positions and intensities of the lines in the Raman spectra on the period of the superlattice are determined, and microscopic nature of optical phonon modes is established. The doublet structure of the E(TO) lines localized in the GaN and AlN layers of superlattice, genetically related to the E 2(high) and E1 phonon branches of the bulk crystal, is first discovered and explained. A strong dependence of the polar modes localized in the AlN layer on the thickness of layer forming the superlattice is revealed. The results of complex studies will improve the accuracy of quantitative estimation of important parameters of superlattice structures and can be used to optimize growth parameters for the fabrication of structurally perfect short-period GaN/AlN superlattices.

Extraction of Valuable Metals and Preparation of Mesoporous Materials from Circulating Fluidized Bed-Derived Fly Ash via an Acid-Alkali-Based Alternate Method.

Stringent leaching conditions including high pressure, temperature, and chemical consumption limit the extraction of valuable metals from circulating fluidized bed-derived high-alumina fly ash (CFB-HAFA) via the acid leaching method. In the present study, a complex utilization of CFB-HAFA, including the extraction of valuable metals (Al, Li, and Ga) and preparation of mesoporous material, is realized via a moderate acid–alkali-based alternate method. The results show that 82, 78, and 69% of Al, Li, and Ga, respectively, in CFB-HAFA are extracted by two treatments of acid leaching under moderate conditions of 15 wt % HCl concentration and 90 °C leaching temperature. The leaching behaviors of metals follow a shrinking core model, and the leaching process is first controlled by the surface chemical reaction at the initial stage and H+ diffusion thereafter. Numerous slit-shaped mesopores form in the residue during acid leaching. The final residue with a specific surface area of 273 m2/g can be used as an efficient adsorbent for removing methylene blue from dye wastewater. The maximum adsorption capacity is approximately 140.0 mg/g at room temperature. The Langmuir adsorption isotherm and pseudo second-order model can well describe the adsorption process and kinetics, implying that the adsorption is a monolayer and chemical adsorption.

Insights into the Composition and Structural Chemistry of Gallium(I) Triflate

Abstract“GaOTf” is a simple, convenient source of low‐valent gallium for synthetic chemistry and catalysis. However, little is currently known about its composition or reactivity. In this work, 71Ga NMR spectroscopy shows the presence of [Ga(arene)n]+ salts on oxidation of Ga metal with AgOTf in arene solvents. However, a more complex picture of speciation is uncovered by X‐ray diffraction studies. In all cases, mixed‐valence compounds containing Ga‐arene and Ga‐OTf coordination motifs, in addition to an unusual “naked” [Ga]+ ion, are found. Addition of 18‐crown‐6 allows for the isolation of a discrete GaI crown complex. Evidence of a potential intermediate in the formation of “GaOTf” has been isolated in the form of the bimetallic silver(I)/gallium(I) cluster anion [Ag4{Ga(OTf)3}4(μ‐Ga)6(OTf)4]2−.

Insights into the Composition and Structural Chemistry of Gallium(I) Triflate.

“GaOTf” is a simple, convenient source of low‐valent gallium for synthetic chemistry and catalysis. However, little is currently known about its composition or reactivity. In this work, 71Ga NMR spectroscopy shows the presence of [Ga(arene)n]+ salts on oxidation of Ga metal with AgOTf in arene solvents. However, a more complex picture of speciation is uncovered by X‐ray diffraction studies. In all cases, mixed‐valence compounds containing Ga‐arene and Ga‐OTf coordination motifs, in addition to an unusual “naked” [Ga]+ ion, are found. Addition of 18‐crown‐6 allows for the isolation of a discrete GaI crown complex. Evidence of a potential intermediate in the formation of “GaOTf” has been isolated in the form of the bimetallic silver(I)/gallium(I) cluster anion [Ag4{Ga(OTf)3}4(μ‐Ga)6(OTf)4]2−.

Study on the Variation of Surface Morphology and Residual Stress Under Various Thermal Annealing Conditions with Bulk GaN Substrates Grown by HVPE

We investigated the effects of different thermal treatment conditions on the surface and internal residual strains of bulk GaN grown by hydride vapor phase epitaxy (HVPE). Thermal annealing was performed at 700–1000 °C for 1–5 h in nitrogen atmosphere. The GaN was characterized by atomic force microscopy, energy dispersive spectrometry, X-ray photoelectron spectroscopy, Raman spectroscopy, and by high-resolution X-ray diffractometer. The experimental results demonstrated that thermal decomposition and oxidation occurred on the surface of GaN when exposed to heat over a long time, or even at a low temperature, as compared to thermal decomposition of GaN in ambient nitrogen. The internal residual stress of GaN was relaxed most effectively when annealing at 900 °C for 3 h, and it was confirmed that the crystal quality is best under this condition. We also confirmed that the effect of annealing was extremely beneficial because native oxide impurities were removed most effectively in this condition. However, Ga metal or oxide could formed due to the occurrence of slight thermal decomposition on the surface.

Recovery of gallium from yellow phosphorus flue dust by vacuum carbothermal reduction

Yellow phosphorus flue dust (YPFD) is a kind of solid waste generated from yellow phosphorus production. Because it contains approximately 0.05% of gallium (Ga), the recovery of Ga from YPFD has attracted the interest of many researchers. To reduce environmental pollution and storage problems associated with YPFD, a new vacuum thermal reduction method to recover Ga from YPFD was proposed in this study. Thermodynamic calculations and thermogravimetric analysis were first used to determine the initial reaction temperature between Ga2O3 and C. High-purity Ga2O3 and activated carbon were evenly mixed and heated at 1273 K and 10 Pa for 2 h. Experimental results showed that metallic Ga could be obtained in the condensation zone by vacuum carbothermal reduction. Based on this result, we next attempted to recover Ga from YPFD by vacuum carbothermal reduction. YPFD containing 30 wt% carbon was heated at 1273 K and 10 Pa for 2 h, and the experimental results also yielded Ga enrichment in the condensation zone. Therefore, this study provides a new and potential useful technology for recovery of Ga from YPFD, as well as a certain practical approach to comprehensively utilizing such industrial waste.

Electrocatalytic effect of 3D porous sulfur/gallium hybrid materials in lithium–sulfur batteries

Lithium–sulfur battery has long been considered as the best choice for the next generation secondary battery. However, the intrinsic insulativity of sulfur and the polysulfide shuttle effect have been the key problems that hinder the commercialization of lithium sulfur batteries. Here, using a facile shearing implement assists thermal synthesis process, in which liquid metal gallium and sulfur (mass ratio1:10) are the only reactants, we create a 3D porous sulfur/gallium hybrid materials (S/Ga). Micro/nanometer liquid metal gallium particles embed in the porous sulfur. The S/Ga cathode lithium cell exhibits a high Coulombic efficiencies of 98.7%, and high specific capacities of 1044 mAh g−1 after 100 cycles at 1.0 mA cm−2, and good cyclic stability. During first cycle discharge process of the S/Ga cathode, the sulfur reduces to Li2S8 and dissolves in the electrolyte, then the liquid metal Ga has an intimate electrical contact with conductive carbon substrates. Electrons are easily transferred to high conductive liquid metal Ga. Due to the electron abundance on Ga surface, it shows an electrocatalytic effect for the conversion of soluble lithium polysulfides (Li2S4-8) to Li2S2/Li2S, thus improving S utilization and cyclic stability.

Revealing the Role of Liquid Metals at the Anode-Electrolyte Interface for All Solid-State Lithium-Ion Batteries.

All-solid-state lithium-ion batteries (ASSLIBs) are receiving tremendous attention for safety concerns over liquid system. However, current ASSLIBs still suffer from poor cycling and rate performance because of unfavorable interfacial contact between solid electrolyte and electrodes, especially in the alloy-based anode. To wet the solid electrode/electrolyte interface, accommodate volume change, and further boost kinetics, liquid metal Ga is introduced into the representative Sb anode, and its corresponding role is comprehensively revealed by experimental results and theoretical calculations for the first time. In addition to interface contact and strain accommodation, with the aid of in situ generation of liquid metal Ga, the lithiation/de-lithiation activity of Sb is stimulated, showing outstanding rate and cycling performance in half cells. Furthermore, benefited from the in situ chemical reaction, TiS2 powder can be directly used to construct a novel "Li-free" TiS2|LiBH4|GaSb full cell, which exhibits an outstanding capacity retention of 226 mA h g-1 after 1000 cycles at a current density of 0.5 A g-1. This work provides guidance for implementing future rational design of alloy anodes within ASSLIBs.

Characterization of a novel LmSAP gene promoter from Lobularia maritima: Tissue specificity and environmental stress responsiveness.

Halophyte Lobularia maritima LmSAP encodes an A20AN1 zinc-finger stress-associated protein which expression is up-regulated by abiotic stresses and heavy metals in transgenic tobacco. To deepen our understanding of LmSAP function, we isolated a 1,147 bp genomic fragment upstream of LmSAP coding sequence designated as PrLmSAP. In silico analyses of PrLmSAP revealed the presence of consensus CAAT and TATA boxes and cis-regulatory elements required for abiotic stress, phytohormones, pathogen, and wound responses, and also for tissue-specific expression. The PrLmSAP sequence was fused to the β-glucuronidase (gusA) reporter gene and transferred to rice. Histochemical GUS staining showed a pattern of tissue-specific expression in transgenic rice, with staining observed in roots, coleoptiles, leaves, stems and floral organs but not in seeds or in the root elongation zone. Wounding strongly stimulated GUS accumulation in leaves and stems. Interestingly, we observed a high stimulation of the promoter activity when rice seedlings were exposed to NaCl, PEG, ABA, MeJA, GA, cold, and heavy metals (Al3+, Cd2+, Cu2+ and Zn2+). These results suggest that the LmSAP promoter can be a convenient tool for stress-inducible gene expression and is a potential candidate for crop genetic engineering.