Introduction Of Metal Cations Research Articles

Effects of different glass formers on Li2S–P2S5–MS2(M = Si, Ge, Sn) chalcogenide solid‐state electrolytes

AbstractChalcogenide solid‐state electrolytes (SSEs) have been receiving growing attentions due to their high ionic conductivity and suitable mechanic properties, especially the Li2S–P2S5systems incorporated with a second glass network formers (Si, Ge, Sn, and so on) besides P. Although the ionic conductivities are generally enhanced with the second glass network formers, the comprehensive effects of different glass formers on other properties, including electrochemical, cycling, and air stability, remain elusive. To acquire deeper understanding, herein, three common but representative glass network formers (SiS2, GeS2, and SnS2) were introduced into Li2S–P2S5, and their individual effects were investigated systematically. The results of multiscale characterizations before and after lithium stripping/plating cycling confirmed that the introduction of metal cations (Ge, Sn) generally leads to worse electrochemical stability and shorter cycle life of these SSEs toward lithium metal compared with SSEs with nonmetal cation (Si) modification. However, the air stability is related to the binding energy of M–S (M = Si, Ge, Sn), which is consistent with the hard base soft acid theory. This work provides valuable understanding for designing pragmatic Li2S–P2S5–MS2‐based SSEs with high electrochemistry, cycling, and air stability.

Variable HOF-derived carbon-coated cobalt phosphide for electrocatalytic oxygen evolution

A structural and morphological transformation of a hydrogen-bonded organic framework (HOF) based on 1,3,5-benzentricarboxylic acid (H3BTC) is observed. With the introduction of metal cations, especially Co(II) ion, these weaker hydrogen bonds linked in this bulk HOF of BTC can be easily broken to obtain the ultrathin wire-shaped product, denoted as Co-Fiber. That is mainly for the reason that the divalent cobalt ions with modest polarity exhibit moderate disturbance and destruction to H-bonding networks. Following calcination and phosphatization, abundant HOF-derived porous carbon-coated CoP particles in CoP/NCNT/PC inherit the morphology of Co-Fiber and endow with in-situ formed N-doped multi-walled carbon nanotubes. Initial electrochemical activation of the CoP/NCNT/PC catalyst promotes the formation of the electrocatalytically active species of cobalt oxyhydroxide for efficient oxygen evolution reaction (OER) in 1.0 M KOH aqueous solution. The obtained CoP/NCNT/PC composite exhibits an outstanding OER performance with the low overpotential of 282 mV at 10 mA cm−2, the relatively small Tafel value (103.7 mV dec−1), and the long-term durability remaining 90.5% over 10 h. The reasonable and facile method to synthesize low-cost, efficient and robust CoP/NCNT/PC shows great potential to substitute noble-metal based electrocatalysts for OER. Meanwhile, it will provide a new way for the application of HOF-derived carbon nanomaterials in the new energy field.

Polyoxomolybdate Layered Crystals Constructed from a Heterocyclic Surfactant: Syntheses, Pseudopolymorphism and Introduction of Metal Cations.

Crystals with layered structures are crucial for the construction of functional materials exhibiting intercalation, ionic conductivity, or emission properties. Polyoxometalate crystals hybridized with surfactant cations have distinct layered packings due to the surfactants which can form lamellar structures. Introducing metal cations into such polyoxometalate-surfactant hybrid crystals is significant for the addition of specific functions. Here, polyoxomolybdate–surfactant hybrid crystals were synthesized as single crystals, and unambiguously characterized by X-ray structure analyses. Octamolybdate ([Mo8O26]4–, Mo8) and heterocyclic surfactant of 1-dodecylpyridinium (C12py) were employed. The hybrid crystals were composed of α-type and β-type Mo8 isomers. Two crystalline phases containing α-type Mo8 were obtained as pseudopolymorphs depending on the crystallization conditions. Crystallization with the presence of rubidium and cesium cations caused the formation of metal cation-introduced hybrid crystals comprising β-Mo8 (C12py-Rb-Mo8 and C12py-Cs-Mo8). The yield of the C12py-Rb-Mo8 hybrid crystal was almost constant within crystallization temperatures of 279–303 K, while that of C12py-Cs-Mo8 decreased over 288 K. This means that the C12py-Mo8 hybrid crystal can capture Rb+ and Cs+ from the solution phase into the solids as the C12py-Rb-Mo8 and C12py-Cs-Mo8 hybrid crystals. The C12py-Mo8 hybrid crystals could be applied to ion-capturing materials for heavy metal cation removal.

Bone cements in the calcium phosphate–chitosan systems containing magnesium and zinc

Based on studying the possibility of the introduction of physiologically important cations into a cementing system, technology of fabrication of highly deformable calcium phosphate cements has been developed for bone tissue reconstruction in medicine. It has been elucidated that the method of introduction of metal cations (magnesium, zinc) into the cementing system has an effect on the formation of the microstructure and properties. The in vitro degradation of composite cements in simulated body fluids has been studied. Results have been obtained for the development of cements with tailored properties, which can be varied in different ranges.

Influence of metal coating methods on the activity of bimetal-containing zeolite catalysts of Co, Pd-ZSM-5 in carbon monoxide oxidation

It has been established that catalytic activity in the CO oxidation of bimetal-containing zeolite Co,Pd-systems based on ZSM-5 and obtained via ion exchange and impregnation at different orders of the introduction of metal cations is higher than that of monometal-containing systems Co-ZSM-5 and Pd—ZSM-5. Through TPD of NH3, it was determined that coordination-unsaturated bicationic associates are formed in Co,Pd/ZSM-5 zeolites obtained by ion exchange. It was found that the activity of bimetal-containing systems depends on the relation of the active components.

A Soluble and Highly Conductive Ionomer for High‐Performance Hydroxide Exchange Membrane Fuel Cells

Hydrogen proton exchange membrane fuel cells (PEMFCs) have been demonstrated to have high power density and reasonable energy density. Their commercialization, however, has been hampered by the high cost and low durability of their electrocatalysts. By switching from an acidic medium to a basic one, hydroxide (OH ) exchange membrane fuel cells (HEMFCs) have the potential to solve the problems of catalyst cost and durability while achieving high power and energy density. In a basic environment, the cathode oxygen reduction over-potential can be significantly reduced, leading to high fuel cell efficiency, and catalysts in basic medium are also more durable. In addition, the facile cathode kinetics allows nonprecious metals to be used as catalysts, thus drastically reducing the cost of the fuel cell. Further, HEMFCs can offer fuel flexibility (e.g., methanol, ethanol, ethylene glycol, etc.) because of their low overpotential for hydrocarbon fuel oxidation and reduced fuel crossover. One of the most significant problems for HEMFCs is the lack of a soluble ionomer that can be used in the catalyst layer to build an efficient three-phase boundary and thus drastically improve the utilization of the catalyst particles and reduce the internal resistance. One of the most desirable properties of an ionomer for use in the catalyst layer is high solubility in low-boiling-point water-soluble solvents such as ethanol and (nor 2-)propanol, because these solvents are easy and safe to handle and remove during the electrode preparation. The ionomer should also have high hydroxide conductivity and alkaline stability. For PEMFCs, Nafion has been the ionomer of choice because it meets these requirements. But for HEMFCs, the most commonly used material for the hydroxide exchange membrane (HEM) is a quaternary ammonium hydroxide containing polymer that has poor solubility in the aforementioned simple solvents, low hydroxide conductivity, and poor alkaline stability. For example, Tokuyama Co. very recently reported two types of soluble quaternary ammonium hydroxide containing polymers (product code: A3Ver2, soluble in tetrahydrofuran or n-propanol, and AS-4, soluble in n-propanol); however, as a result of their low hydroxide conductivity, their incorporation into the catalyst layers of HEMFCs only led to a moderate improvement in performance. In another case, Park et al. prepared an ionomer solution of the trimethylamine (TMA) and N,N,N’,N’-tetramethyl-1,6-hexanediamine (TMHDA) based polysulfone– methylene quaternary ammonium hydroxide (T/TPQAOH) in dimethylacetamide (DMAc, b.p. 166 8C). Similar to the Tokuyama results, the low hydroxide conductivity of the ionomer significantly limited the improvement in fuel cell performance, and in addition, removal of the high-boilingpoint solvent is considered difficult and unsafe in the presence of finely dispersed catalysts. Owing to the lack of a soluble highly conductive solid ionomer, aqueous solutions of KOH or NaOH have been previously used in the electrodes, where the introduction of metal cations (M) offsets the key advantages of a HEMFC over traditional liquid-electrolytebased alkaline fuel cells (AFCs). Furthermore, owing to the lack of a good ionomer as the binder, non-ionic conductive PTFE and proton-conductive Nafion ionomers were used as substitutes in the electrodes, even though these materials were known to have no hydroxide conductivity. Recently, Varcoe et al. reported a TMHDA-based polyvinylbenzylcrosslinked quaternary ammonium hydroxide (TPCQAOH) electrochemical interface to enhance HEMFC performance. Because the polymer used was not soluble in ionomer form, one could question its ability to form an efficient three-phase-boundary structure in the catalyst layer, thereby limiting performance. Moreover, the hydroxide conductivity and stability of the electrochemical interface are still of concern because it is based on quaternary ammonium hydroxide groups. Quaternary phosphonium containing polymers showed excellent solubility in methanol. The strong basicity of the tertiary phosphine suggests that quaternary phosphonium hydroxides are very strong bases. Therefore in this work, we synthesized a new quaternary phosphonium based ionomer that is soluble in low-boiling-point water-soluble solvents and is highly hydroxide conductive: tris(2,4,6-trimethoxyphenyl) polysulfone-methylene quaternary phosphonium hydroxide (TPQPOH; Scheme 1). The TPQPOH ionomer exhibits excellent solubility in pure methanol, ethanol, and n-propanol and in their aqueous solutions (50 wt% in water, see Table S1 in the Supporting Information). On the other hand, the TPQPOH is insoluble in pure water, even at 80 8C, suggesting that it can be used in the [*] Dr. S. Gu, Dr. R. Cai, T. Luo, Dr. Z. Chen, M. Sun, Y. Liu, Prof. Dr. Y. S. Yan Department of Chemical and Environmental Engineering University of California—Riverside Riverside, CA 92521 (USA) Fax: (+1)951-827-5696 E-mail: yushan.yan@ucr.edu Homepage: http://www.engr.ucr.edu/faculty/chemenv/ yushanyan.html

Gas transport properties of carbon molecular sieve membranes derived from metal containing sulfonated poly(phenylene oxide)

Hollow-fiber carbon molecular sieve (CMS) membranes derived from sulfonated poly(phenylene oxide) (SPPO) were studied. Mono-, di- and trivalent metal cations such as Na +, Mg 2+, Al 3+, Ag +, Cu 2+ and Fe 3+ were substituted to the proton of sulfonic acid group of SPPO by the ion-exchange method to investigate the effects on gas transport properties for SPPO CMS membranes. In the case of H-SPPO, CMS membranes exhibited higher performance than those of the polymeric precursor, and maximum permeability was obtained when pyrolyzed at 923 K. The introduction of metal cations into SPPO affected the structures of the resulting CMS membranes, of which the Ag- and Cu- form enhanced overall permeabilities. In addition, Fe-SPPO CMS membranes increased He/N 2 and H 2/N 2 permselectivities compared to non-substituted CMS membranes prepared by the same pyrolysis procedure. The highest performance was attained by the Ag-SPPO CMS membrane pyrolyzed at 923 K, where O 2 permeability was 178 Barrer and O 2/N 2 permselectivity was 8.7 at 298 K.

Bi-, TRI- and Penta-Nuclear Complexes of Chelating Schiff Bases Derived from o-Acetoacetylphenol and Amine Complexes, [Ni(1,2-pn)2Cl2]·3H2O and [Cu(1,2-pn)2]SO4·2H2O

Two novel macroacylic Schiff base ligands were prepared by condensation of two diamine metal complexes, [Ni(1,2-pn)2Cl2]·3H2O and [Cu(1,2-pn)2]SO4·2H2O with o-acetoacetylphenol. The ligands MH6L(M = Ni or Cu) are hexabasic and contain two O4 coordination sites. They act as ligands towards transition metal ions yielding homo- and heteronuclear complexes of the type [NiH4 LCu(H2O)2]·4H2O, [MH2LM' 2(H2O)6], [MLM' 4(H2O)8], [MH2 LCe2(NO>3)2(H2O)2] and [NiLTh2(NO3)2(H2O)2] (M = Ni or Cu; M' = Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Ce(III), Th(IV) and UO2 (VI)). The complexes were characterized by elemental analysis, thermogravimetric analysis (TGA), IR, visible and ESR spectra, magnetic susceptibility measurements and mass spectrometry. Magnetic moments were altered by the introduction of metal cations besides the one already present in the complex ligands. The M' cations were linked to two ketonic oxygen atoms and two phenyl oxygen atoms in [NiH6 L(H2O)2] and [CuH6 L] complex ligands. All homo- and hetero-, bi- and tri-nuclear complexes show antiferromagnetic interactions which are attributed to inter- or intramolecular interactions of the metal cations. Mass spectra of the complex ligands and selected homo- and heteronuclear complexes support the formula weights of these complexes. Visible and ESR spectra as well as magnetic moments indicated that the parent mononuclear complex ligands [MH6 L] have an octahedral geometry for Ni(II) and a square-planar geometry distorted towards tetrahedral for Cu(II). The metal cations in bi-, tri- and pentanuclear complexes are octahedral or square-planar. The octahedral configuration is completed by chloride anions and/or solvent molecules.

Preparation of Metallosilicates with ZSM-5 Type Structure by Atom-Planting Method

Abstract Aluminosilicates, gallosilicates, and indosilicates with the ZSM-5 type structure were prepared by the “Atom-Planting method”. The introduction of metal cations into the framework of highly siliceous ZSM-5 zeolites was confirmed by IR and unit cell volume measurements. The acidic properties of these metallosilicates were examined by pyridine-IR and NH3-temperature programmed desorption spectroscopies. The increasing order of the acid strengths of the metallosilicates is indosilicate<gallosilicate<aluminosilicate.