Chemical Precursors Research Articles

Synthesis of Nanoparticles by Spark Discharge as a Facile and Versatile Technique of Preparing Highly Conductive Pt Nano-Ink for Printed Electronics.

A cost-effective, scalable and versatile method of preparing nano-ink without hazardous chemical precursors is a prerequisite for widespread adoption of printed electronics. Precursor-free synthesis by spark discharge is promising for this purpose. The synthesis of platinum nanoparticles (PtNPs) using a spark discharge under Ar, N2, and air has been investigated to prepare highly conductive nano-ink. The size, chemical composition, and mass production rate of PtNPs significantly depended on the carrier gas. Pure metallic PtNPs with sizes of 5.5 ± 1.8 and 7.1 ± 2.4 nm were formed under Ar and N2, respectively. PtNPs with sizes of 18.2 ± 9.0 nm produced using air consisted of amorphous oxide PtO and metallic Pt. The mass production rates of PtNPs were 53 ± 6, 366 ± 59, and 490 ± 36 mg/h using a spark discharge under Ar, N2, and air, respectively. It was found that the energy dissipated in the spark gap is not a significant parameter that determines the mass production rate. Stable Pt nano-ink (25 wt.%) was prepared only on the basis of PtNPs synthesized under air. Narrow (about 30 μm) and conductive Pt lines were formed by the aerosol jet printing with prepared nano-ink. The resistivity of the Pt lines sintered at 750 °C was (1.2 ± 0.1)·10−7 Ω·m, which is about 1.1 times higher than that of bulk Pt.

Chemical Bath Deposition of ZnO Nanowires Using Copper Nitrate as an Additive for Compensating Doping.

The controlled incorporation of dopants like copper into ZnO nanowires (NWs) grown by chemical bath deposition (CBD) is still challenging despite its critical importance for the development of piezoelectric devices. In this context, the effects of the addition of copper nitrate during the CBD of ZnO NWs grown on Au seed layers are investigated in detail, where zinc nitrate and hexamethylenetetramine are used as standard chemical precursors and ammonia as an additive to tune the pH. By combining thermodynamic simulations with chemical and structural analyses, we show that copper oxide nanocrystals simultaneously form with ZnO NWs during the CBD process in the low-pH region associated with large supersaturation of Cu species. The Cu(II) and Zn(II) speciation diagrams reveal that both species show very similar behaviors, as they predominantly form either X2+ ions (with X = Cu or Zn) or X(NH3)42+ ion complexes, depending on the pH value. Owing to their similar ionic structures, Cu2+ and Cu(NH3)42+ ions preferentially formed in the low- and high-pH regions, respectively, are able to compete with the corresponding Zn2+ and Zn(NH3)42+ ions to adsorb on the c-plane top facets of ZnO NWs despite repulsive electrostatic interactions, yielding the significant incorporation of Cu. At the highest pH value, additional attractive electrostatic interactions between the Cu(NH3)42+ ion complexes and negatively charged c-plane top facets further enhance the incorporation of Cu into ZnO NWs. The present findings provide a deep insight into the physicochemical processes at work during the CBD of ZnO NWs following the addition of copper nitrate, as well as a detailed analysis of the incorporation mechanisms of Cu into ZnO NWs, which are considered beyond the only electrostatic forces usually driving the incorporation of dopants such as Al and Ga.

A simplified model for the vapor – Solid distribution of Silicon Germanium Chemical Vapor Deposition

A simplified model of Silicon Germanium Chemical Vapor Deposition is proposed for the determination of Vapor – Solid distributions via any precursor route. The incorporation of the atomic element into the crystal lattice imposes to the chemical precursor the loss of all the ligands. Thus, dichlorosilane, silane, and disilane are discriminated on the basis of the amount of the atomic element brought into the equilibrium, instead of being different chemicals. Experimental trends show the ratio relative to silane is 2 for disilane and about ½ for dichlorosilane. The ratio relative to Si{100} is 0.59 for Si{110} and 0.82 for Si{111} for a growth via dichlorosilane and germane. Furthermore, Silicon Germanium alloy content is controlled by a thermodynamic equilibrium and the theoretical VS distribution is demonstrated for a growth via silane and germane. VS distribution of any chemistry onto any substrate orientation can therefore be estimated with the application of a straightforward corrective coefficient to a reference silane and germane chemistry.

Volatile Iridium and Platinum MOCVD Precursors: Chemistry, Thermal Properties, Materials and Prospects for Their Application in Medicine

Interest in iridium and platinum has been steadily encouraged due to such unique properties as exceptional chemical inertia and corrosion resistance, high biological compatibility, and mechanical strength, which are the basis for their application in medical practice. Metal-organic chemical vapor deposition (MOCVD) is a promising method to fabricate Ir and Pt nanomaterials, multilayers, and heterostructures. Its advantages include precise control of the material composition and microstructure in deposition processes at relatively low temperatures onto non-planar substrates. The development of MOCVD processes is inextricably linked with the development of the chemistry of volatile precursors, viz., specially designed coordination and organometallic compounds. This review describes the synthesis methods of various iridium and platinum precursors, their thermal properties, and examples of the use of MOCVD, including formation of films for medical application and bimetallics. Although metal acetylacetonates are currently the most widely used precursors, the recently developed heteroligand Ir(I) and Pt(IV) complexes appear to be more promising in both synthetic and thermochemical aspects. Their main advantage is their ability to control thermal properties by modifying several types of ligands, making them tunable to deposit films onto different types of materials and to select a combination of compatible compounds for obtaining the bimetallic materials.

Additional Role of Nicotinic Acid Hydroxylase for the Transformation of 3-Succinoyl-Pyridine by Pseudomonas sp. Strain JY-Q.

Nicotine and nicotinic acid (NA) are both considered to be representatives of N-heterocyclic aromatic compounds, and their degradation pathways have been revealed in Pseudomonas species. However, the cooccurrence of these two pathways has only been observed in Pseudomonas sp. strain JY-Q. The nicotine pyrrolidine catabolism pathway of strain JY-Q consists of the functional modules Nic1, Spm, and Nic2. The module enzyme, 3-succinoylpyridine monooxygenase (Spm), catalyzes transformation of 3-succinoyl-pyridine (SP) to 6-hydroxy-3-succinoyl-pyridine (HSP). There exist two homologous but not identical Spm enzymes (namely, Spm1 and Spm2) in JY-Q. However, when spm1 and spm2 were both in-frame deleted, the mutant still grew well in basic salt medium (BSM) supplemented with nicotine as the sole carbon/nitrogen nutrition, suggesting that there exists an alternative pathway responsible for SP catabolism in JY-Q. NicAB, an enzyme accounting for NA hydroxylation, contains reorganized domains similar to those of Spm. When the JY-Q_nicAB gene (nicAB in strain JY-Q) was introduced into another Pseudomonas strain, one that is unable to degrade NA, the resultant recombinant strain exhibited the ability to transform SP to HSP, but without the ability to metabolize NA. Here, we conclude that NicAB in strain JY-Q exhibits an additional role in SP transformation. The other genes in the NA cluster, NicXDFE (Nic2 homolog), then also exhibit a role in subsequent HSP metabolism for energy yield. This finding also suggests that the cooccurrence of nicotine and NA degradation genes in strain JY-Q represents an advantage for JY-Q, making it more effective and flexible for the degradation of nicotine.IMPORTANCE 3-Succinoyl-pyridine (SP) and 6-hydroxy-3-succinoyl-pyridine (HSP) are both valuable chemical precursors to produce insecticides and hypotensive agents. SP and HSP could be renewable through the nicotine microbial degradation pathway, in which 3-succinoylpyridine monooxygenases (Spm) account for transforming SP into HSP in Pseudomonas sp. strain JY-Q. However, when two homologous Spm genes (spm1 and spm2) were knocked out, the mutant retained the ability to degrade nicotine. Thus, in addition to Spm, JY-Q should have an alternative pathway for SP conversion. In this research, we showed that JY-Q_NicAB was responsible for this alternative SP conversion. Both of the primary functions for nicotinic acid dehydrogenation and the additional function for SP metabolism were detected in a recombinant strain harboring JY-Q_NicAB. As a result, both nicotinic acid and nicotine degradation pathways in JY-Q contribute to its remarkable nicotine tolerance and nicotine degradation availability. These findings also provide one more metabolic engineering strategy for accumulation for value-added intermediates.

Nanoparticles Size Distribution Assessment During Early Synthesis Stages

Nanotechnology, an innovative field of material science, designs and produces nanostructures materials with unique properties that make them suited for various bioengineering applications. The shape and the dimension are the main variables depending on the method of synthesis or chemical precursors. Silver nanoparticles obtained through chemical synthesis exhibit as strong antibacterial effect if their size lays in a well-defined range. However, a small size of such particles, in the range of nanometers to several tens of nanometers, requires specific techniques as Dynamic Light Scattering or Transmission Electron Microscopy, both being affected by certain assumptions or by the high cost and long time required for a measurement. A nonconventional method based on Direct Particle Tracking can be used to produce the particle size distribution in the early nanoparticle synthesis stages. The work presents a realistic computer simulation of nanoparticle diffusion performed with the CHODIN code and a size distribution assessment using a code for Direct Particle Tracking written for this purpose. The results are consistent with the particle size used for simulation and states as a proof of concept for using the Direct Particle Tracking method for particle size distribution in the early stages of nanoparticle synthesis.

ActDES - a curated Actinobacterial Database for Evolutionary Studies.

Actinobacteria is a large and diverse phylum of bacteria that contains medically and ecologically relevant organisms. Many members are valuable sources of bioactive natural products and chemical precursors that are exploited in the clinic and made using the enzyme pathways encoded in their complex genomes. Whilst the number of sequenced genomes has increased rapidly in the last 20 years, the large size, complexity and high G+C content of many actinobacterial genomes means that the sequences remain incomplete and consist of large numbers of contigs with poor annotation, which hinders large-scale comparative genomic and evolutionary studies. To enable greater understanding and exploitation of actinobacterial genomes, specialized genomic databases must be linked to high-quality genome sequences. Here, we provide a curated database of 612 high-quality actinobacterial genomes from 80 genera, chosen to represent a broad phylogenetic group with equivalent genome re-annotation. Utilizing this database will provide researchers with a framework for evolutionary and metabolic studies, to enable a foundation for genome and metabolic engineering, to facilitate discovery of novel bioactive therapeutics and studies on gene family evolution. This article contains data hosted by Microreact.

Catalytic methods for chemical recycling or upcycling of commercial polymers.

Polymers (plastics) have transformed our lives by providing access to inexpensive and versatile materials with a variety of useful properties. While polymers have improved our lives in many ways, their longevity has created some unintended consequences. The extreme stability and durability of most commercial polymers, combined with the lack of equivalent degradable alternatives and ineffective collection and recycling policies, have led to an accumulation of polymers in landfills and oceans. This problem is reaching a critical threat to the environment, creating a demand for immediate action. Chemical recycling and upcycling involve the conversion of polymer materials into their original monomers, fuels or chemical precursors for value-added products. These approaches are the most promising for value-recovery of post-consumer polymer products; however, they are often cost-prohibitive in comparison to current recycling and disposal methods. Catalysts can be used to accelerate and improve product selectivity for chemical recycling and upcycling of polymers. This review aims to not only highlight and describe the tremendous efforts towards the development of improved catalysts for well-known chemical recycling processes, but also identify new promising methods for catalytic recycling or upcycling of the most abundant commercial polymers.

Resin-supported iridium complex for low-temperature vanillin hydrogenation using formic acid in water.

Biorefinery seeks to utilize biomass waste streams as a source of chemical precursors with which to feed the chemical industry. This goal seeks to replace petroleum as the main feedstock, however this task requires the development of efficient catalysts capable of transforming substances derived from biomass into useful chemical products. In this study, we demonstrate that a highly-active iridium complex can be solid-supported and used as a low-temperature catalyst for both the decomposition of formic acid (FA) to produce hydrogen, and as a hydrogenation catalyst to produce vanillyl alcohol (VA) and 2-methoxy-4-methylphenol (MMP) from vanillin (V); a lignin-derived feedstock. These hydrogenation products are promising precursors for epoxy resins and thus demonstrate an approach for their production without the need for petroleum. In contrast to other catalysts that require temperatures exceeding 100 °C, here we accomplish this at a temperature of <50 °C in water under autogenous pressure. This approach provides an avenue towards biorefinery with lower energy demands, which is central to the decentralization and broad implementation. We found that the high activity of the iridium complex transfers to the solid-support and is capable of accelerating the rate determining step; the decomposition of FA into hydrogen and carbon dioxide. The yield of both VA and MMP can be independently tuned depending on the temperature. The simplicity of this approach expands the utility of molecular metal complexes and provides new catalyst opportunities in biorefinery.

One-step plasma deposited thin SiO x C y films for corrosion resistance of low carbon steel

Tetraethyl orthosilicate (TEOS) was used as a chemical precursor to deposit ultra-thin SiO x C y plasma polymer films onto mild steel surfaces for preventing the corrosion process. The structure–property relationships of the coatings were evaluated by X-ray Photo Spectroscopy (XPS), X-Ray Diffraction (XRD), Fourier Transform InfraRed spectroscopy (ATR-FTIR) and Energy Dispersive X-ray spectroscopy (EDX) completed with Scanning Electron Microscopy (SEM). The SEM micrographs confirmed a pinhole-free surface morphology of the low-pressure deposited plasma polymer films. The TEOS molecules become fragmented in the plasma by numerous collisions with energy-rich electrons and heavier particles. Recombination of fragments and condensation onto the steel substrate is responsible for the formation of organic SiO containing plasma polymer layers. Such thin layers consist of predominantly SiO x structures. Their properties are determined largely by the gap distance between the two samples used as electrodes in the plasma. The efficiency of the corrosion-protecting coating was compared with uncoated samples. The corrosion protection was determined by exposure of samples to 3.5% NaCl aqueous solutions. For this purpose, polarization and Electrochemical Impedance Spectroscopy (EIS) were used to monitor the corrosion. The optimal gap distance between the electrodes was determined for corrosion protection. The best protective efficiency reached more than 97% of the total protection as measured at room temperature.

Novel Magnetic Nanohybrids: From Iron Oxide to Iron Carbide Nanoparticles Grown on Nanodiamonds

The synthesis and characterization of a new line of magnetic hybrid nanostructured materials composed of spinel-type iron oxide to iron carbide nanoparticles grown on nanodiamond nanotemplates is reported in this study. The realization of these nanohybrid structures is achieved through thermal processing under vacuum at different annealing temperatures of a chemical precursor, in which very fine maghemite (γ-Fe2O3) nanoparticles seeds were developed on the surface of the nanodiamond nanotemplates. It is seen that low annealing temperatures induce the growth of the maghemite nanoparticle seeds to fine dispersed spinel-type non-stoichiometric ~5 nm magnetite (Fe3−xO4) nanoparticles, while intermediate annealing temperatures lead to the formation of single phase ~10 nm cementite (Fe3C) iron carbide nanoparticles. Higher annealing temperatures produce a mixture of larger Fe3C and Fe5C2 iron carbides, triggering simultaneously the growth of large-sized carbon nanotubes partially filled with these carbides. The magnetic features of the synthesized hybrid nanomaterials reveal the properties of their bearing magnetic phases, which span from superparamagnetic to soft and hard ferromagnetic and reflect the intrinsic magnetic properties of the containing phases, as well as their size and interconnection, dictated by the morphology and nature of the nanodiamond nanotemplates. These nanohybrids are proposed as potential candidates for important technological applications in nano-biomedicine and catalysis, while their synthetic route could be further tuned for development of new magnetic nanohybrid materials.

Modular Hydrogen Peroxide Electrosynthesis Cell with Anthraquinone-Modified Polyaniline Electrocatalyst

Advanced oxidation processes (AOPs) target the chemical destruction of a wide range of nonbiodegradable, toxic, and recalcitrant organic pollutants instead of removal via physical separation, which produces contaminant-laden concentrates or solids. Hydrogen peroxide (H2O2) is the most widely used precursor that produces a highly reactive and nonselective hydroxyl radical at the site of an AOP through activation by UV irradiation. The potential for AOPs to meet the growing demand of transforming a centralized treatment and distribution practice into a modular, small-scale, and decentralized treatment paradigm can be maximized by innovative technologies that can synthesize precursor chemicals also at the site of water treatment, eliminating the need for a continuous chemical supply. We here present an electrochemical H2O2 generation cell that produces a large quantity of H2O2 while consuming only 0.2 to 20% of the total electricity consumption of AOPs in various AOP application scenarios employing UV activation. We achieve high electrochemical H2O2 production efficiency by synthesizing an anthraquinone-modified polyaniline composite that enables an efficient two-electron oxygen reduction reaction. Polyaniline functions as a conductive support with abundant attachment sites, and anthraquinone ensures selective H2O2 generation. In a flow cell equipped with a gas diffusion cathode, H2O2 can be produced at a rate of 1.80 mol gcatalyst–1 hr–1 at 100 mA with a Faradaic efficiency of 95.83%. Finally, we examined the H2O2 production capability of the device with simulated drinking water and wastewater as feed electrolytes to demonstrate its potential for real-world operation scenarios.

Antidepressant-like effects of a new dihydro isoquinoline and its chemical precursors in mice: involvement of serotonin and dopaminergic systems

This study was aimed to synthesize novel 2-(2-bromophenyl)-N-phenethylacetamides and benzylisoquinoline (BIQ) derivatives to be evaluated as antidepressant-like agents in mice. The phenethylacetamides derivatives were synthesized by coupling aromatic amides to the backbone of 2-bromophenylacetyl chloride. The synthesis of BIQ was achieved by the reaction between synthesized phenethylacetamides and 2-chloropyridine. The structures of compounds were established mainly by 1D and 2D NMR spectra. Those compounds obtained with moderate to good yields were evaluated as antidepressant-like agents in the forced swim test and the open field paradigms in mice. The possible mechanism of those active derivatives was explored by antagonist experiments in combination with p-chloro-phenylalanine methyl ester, reserpine, sulpiride, and dopamine D1 antagonist SCH23390. Also, MAO A and B inhibition assays were performed. Docking studies between the human dopamine D3 receptor and the higher active compound were performed. The results showed that the (2-bromophenyl)-(3,4-dihydroisoquinoline-1-yl)methanone (4a) presented the most potent antidepressant-like effects without modifying the ambulatory activity of experimental mice. Antagonist experiments showed that 4a acted on the serotonergic and dopaminergic receptors. Docking studies indicated a strong affinity between the human dopamine D3 receptor and 4a. Our results showed that BIQ 4a has an antidepressant-like effect that is possibly mediated by an interaction with the presynaptic serotonin receptors and dopaminergic, D1, D2, and D3, receptors. This study highlights the pharmacological potential of halogenated BIQs in the treatment of some depressive disorders.

Peculiarities of the structural and optical properties of rare-earth-doped phosphate glasses for temperature sensing applications

Eu, Er, Yb-Er, and Dy-doped phosphate glasses were prepared by a wet-route processing of chemical precursors followed by melt-quenching and annealing. XRD measurements highlighted the amorphous nature of the investigated glasses. UV-Vis absorption spectra revealed peaks specific to f-f electronic transitions of the doping ions whereas FTIR and Raman spectroscopy proved the vitreous network forming role of phosphorous pentoxide. Luminescence spectra in the Vis domain, at RT, showed emission bands characteristic to the ion transitions from the excited states to the ground state. The luminescence spectra collected in the 25-160°C range exhibited a decrease of the emission intensity with temperature rise. In the case of Eu and Dy-doped glasses a relatively small decrease of the emission intensity with temperature is observed by comparison with Er and, respectively, Yb-Er-doped glass where a significant change of the emission intensity is noticed, which recommends the latter as promising candidate for sensing devices.

Janus electrocatalytic flow-through membrane enables highly selective singlet oxygen production

The importance of singlet oxygen (1O2) in the environmental and biomedical fields has motivated research for effective 1O2 production. Electrocatalytic processes hold great potential for highly-automated and scalable 1O2 synthesis, but they are energy- and chemical-intensive. Herein, we present a Janus electrocatalytic membrane realizing ultra-efficient 1O2 production (6.9 mmol per m3 of permeate) and very low energy consumption (13.3 Wh per m3 of permeate) via a fast, flow-through electro-filtration process without the addition of chemical precursors. We confirm that a superoxide-mediated chain reaction, initiated by electrocatalytic oxygen reduction on the cathodic membrane side and subsequently terminated by H2O2 oxidation on the anodic membrane side, is crucial for 1O2 generation. We further demonstrate that the high 1O2 production efficiency is mainly attributable to the enhanced mass and charge transfer imparted by nano- and micro-confinement effects within the porous membrane structure. Our findings highlight a new electro-filtration strategy and an innovative reactive membrane design for synthesizing 1O2 for a broad range of potential applications including environmental remediation.

Condensing water vapor to droplets generates hydrogen peroxide

It was previously shown [J. K. Lee et al., Proc. Natl. Acad. Sci. U.S.A, 116, 19294-19298 (2019)] that hydrogen peroxide (H2O2) is spontaneously produced in micrometer-sized water droplets (microdroplets), which are generated by atomizing bulk water using nebulization without the application of an external electric field. Here we report that H2O2 is spontaneously produced in water microdroplets formed by dropwise condensation of water vapor on low-temperature substrates. Because peroxide formation is induced by a strong electric field formed at the water-air interface of microdroplets, no catalysts or external electrical bias, as well as precursor chemicals, are necessary. Time-course observations of the H2O2 production in condensate microdroplets showed that H2O2 was generated from microdroplets with sizes typically less than ∼10 µm. The spontaneous production of H2O2 was commonly observed on various different substrates, including silicon, plastic, glass, and metal. Studies with substrates with different surface conditions showed that the nucleation and the growth processes of condensate water microdroplets govern H2O2 generation. We also found that the H2O2 production yield strongly depends on environmental conditions, including relative humidity and substrate temperature. These results show that the production of H2O2 occurs in water microdroplets formed by not only atomizing bulk water but also condensing water vapor, suggesting that spontaneous water oxidation to form H2O2 from water microdroplets is a general phenomenon. These findings provide innovative opportunities for green chemistry at heterogeneous interfaces, self-cleaning of surfaces, and safe and effective disinfection. They also may have important implications for prebiotic chemistry.

Alternative Mechanistic Considerations: Charactering Multiple Reaction Pathways for the Oxygen Evolution Reaction

H2 remains an important chemical precursor in processes such as the Haber-Bosch process to synthesize ammonia and hydrocracking for refining of hydrocarbons and also exists as an alternative fuel for transportation. Currently, 95% of H2 is produced by steam methane reforming, whose byproduct is pollutant CO. Electrolysis is a clean, efficient method run at room temperature to split water into H2and O2. However, electrolysis is not cost-competitive with steam methane reforming, utilizing large amounts of platinum group materials. Computational chemistry can give atomic and electronic levels of understanding of a material by identifying highly active facets of a known material or predicting the catalytic potential of unknown materials. We will model catalysts used in the oxygen evolution reaction, the half-cell reaction requiring the most catalyst and occurring many orders of magnitude slower than the hydrogen evolution reaction. We will focus on the effect of the ensemble: modeling different facets of iridium oxide, characterizing all possible configurations of key reaction intermediates, and incorporating explicit solvation to fully understand the nuances of optimizing a premier catalyst such as IrO2. In particular, we will focus our calculations on two facets: (110), the more thermodynamically stable facet and (001), a potentially more active facet due to the presence of undercoordinated, surface Ir sites. We will compare the reaction profile of the ensemble of key reaction intermediates on the (110) versus the (001) facet and in vacuum versus with solvation. The ensemble of intermediates allows us to explore multiple reaction pathways on the surface that have not been characterized.Figure 1. A schematic summarizing the different isomers found at each reaction step (TOP) and the reaction profile of the oxygen evolution reaction on the (110) facet of iridium oxide (BOTTOM). Figure 1

Electrochemical Lithium Recycling System Using High Dense Li-Ion Conducting Solid Electrolyte Toward Renewable and Sustainable Energy Technology

As the lithium-ion battery (LIB) has been widely commercialized for energy storage systems in portable and stationary devices, it’s production and disposal have dramatically increased over the past few decades. In addition, increasing the number of electric vehicles (EVs) causes a more dramatic increase in waste LIBs. As lithium is the key material for LIB, this increasing market trend of LIB leads to lithium source depletion which is an urgent problem for the future LIB market. In addition, waste LIBs can cause serious environmental problems as it contains flammable and explosive materials.To circumvent these issues, various LIB recycling technologies have been researched over the world. The most used hydrometallurgy method leaches waste battery electrode materials into acidic or alkaline conditions to form ionized lithium solution. After leaching, precipitation and extraction methods can be used to obtain lithium chemicals. However, these methods have a problem of using a large amount of toxic acid or alkali chemicals to leach the waste battery materials. This leads to complicate procedure high chemical cost and requires environmental cost for recycling waste LIBs.A new type of lithium recycling system using a solid electrolyte has been proposed to overcome these issues. This electrochemical system is named waste-to-lithium (WTL) recycling system and can simply extract lithium from the waste lithium materials. This system consists of three compartments: the waste cathode compartment, the harvesting anode compartment, and the recycling cathode compartment. Each compartment is physically separated with Li-ion conducting ceramic membrane (LATP), and this membrane can selectively penetrate lithium ions. Waste cathode compartment stores waste LIB materials in the water. By electrochemically charging the WTL system, lithium ions from the waste LIB materials are extracted and transfer to the harvesting anode compartment where the lithium ions form lithium metal by reacting with the electrons. After the charging process, lithium metal can be transformed into lithium precursor chemicals such as LiOH and Li2CO3 by electrochemically discharging it into a recycling cathode compartment that is filled with water.The main key component of the WTL system is Li-ion conducting ceramic membrane. WTL system applied Li1.4Al0.4Ti1.6(PO4)3 (LATP) solid electrolyte as Li-ion conducting ceramic membrane due to the characteristic of high ionic conductivity and high chemical stability in water. However, on account of the poor sinterability of LATP, it is difficult to sinter dense LATP pellet that is enough to block the water ions. Japan company OHARA corporation has sold dense glass Li-ion conducting glass-ceramic (LICGC) pellets for Li-air batteries. However, OHARA employs a melting quenching method to synthesize LICGC glass-ceramic, which melts all the precursor materials at extremely high temperature. In addition, this glass-ceramic includes high-cost germanium materials for high dense glass sintering. These two critical factors lead to the extremely high cost of the OHARA LICGC glass-ceramic pellet. For higher lithium recycling efficiency of the WTL system, water-stable, low-cost solid electrolyte must be applied to the WTL system. For low-cost solid electrolytes, the water-base synthesis method was used to form the LATP pellet, which only uses water during the synthesis process that can lower the price of the procedure. However, this synthesized LATP pellet had low density with a porosity of 6.6%, which permits the water ions through the pellet. To circumvent this porosity issue, pores of the LATP pellet was filled with epoxy-resin polymer. Epoxy-resin has strong adhesion with substrates and has excellent mechanical properties and strong chemical stability. This polymer fills the pores of the LATP and blocks the water penetration through the pellet. The Epoxy-LATP solid electrolyte showed high ionic conductivity over 2×10-4 S/cm, the high bending strength of 47 MPa and stable cycle performance in aqueous solution for 300 hours.By applying the low cost, high dense LATP pellet, the concept of the WTL system is proved using well-known cathode materials from Li-ion batteries such as LiFePO4, LiMnO2, LiNi0.3Mn0.3Co0.3O2 and a commercial Li-ion battery pack. The harvested Li metal shows a purity near 99%, and the produced material after discharging showed a pure Li2CO3 phase. This WTL system will be a promising system for the low-cost and environmentally friendly lithium recycling system for the increasing future lithium demand.

Codeposition of Levodopa and Polyethyleneimine: Reaction Mechanism and Coating Construction.

Mussel-inspired poly(catecholamine) coatings from polydopamine (PDA) have been widely studied to design functional coatings for various materials. The chemical precursor of dopamine (DA), levodopa (l-DOPA, 3,4-dihydroxyphenyl-l-alanine), is known as the main element of mussel adhesive foot protein, but it is relatively hard to be constructed into a desirable coating on a given material surface under the same conditions as those for DA. Herein, we report a codeposition strategy to achieve the rapid fabrication of mussel-inspired coatings by l-DOPAwith polyethyleneimine (PEI) and to deeply understand the formation mechanism of those aggregates and coatings from l-DOPA/PEI. DFT calculations, fluorescence spectra, nuclear magnetic resonance analysis, and liquid chromatography-tandem mass spectrometry identification demonstrate that the formation of l-DOPA/PEI aggregates is effectively accelerated by PEI crosslinking with those intermediates of oxidized l-DOPA, including l-DOPAquinone and 5,6-dihydroxyindole-2-carboxylic acid as well as 5,6-dihydroxyindole, through Michael-addition and Schiff-base reactions. Therefore, we can facilely control the growth rate and the particle size of the l-DOPA/PEI aggregates in the deposition solution by adjusting the concentration of PEI. The coating formation rate of l-DOPA/PEI is four times faster than that of PDA and DA/PEI within 12 h. These l-DOPA/PEI coatings are demonstrated to display potential as structure colors, superhydrophilic surfaces, and antibacterial materials.

First-principles studies of MoF6 absorption on hydroxylated and non-hydroxylated metal oxide surfaces and implications for atomic layer deposition of MoS2

Significant interest in two-dimensional transition metal dichalcogenides has led to numerous experimental studies of their synthesis using scalable vapor phase methods, such as chemical vapor deposition (CVD) and atomic layer deposition (ALD). ALD typically allows lower deposition temperatures, and nucleation of chemical precursors requires reactions with surface functional groups. A common first-principles method used to study ALD modeling is the calculation of activation energy for a proposed reaction pathway. In this work we calculated the partial charge densities, local density of states (LDoS), Bader charge analysis, adsorption energies, and charge density difference using density functional theory (DFT) to investigate the nucleation of MoF6 on three oxide surfaces, including Al2O3, HfO2, and MgO. Our findings indicate that hydroxyl groups (OH) help lower the reaction barrier during the first half-cycle of MoF6 and promote the chemisorption of a precursor on the oxide substrates. This discovery is supported by the formation of highly ionic MFx (M = metal, x = 1, 2, 3) bonds at the oxide surfaces. By comparing surfaces with and without hydroxyl groups, we highlight the importance of surface chemistry.