Metal Acetates Research Articles

Dinuclear group 12 metal phosphates bridged by hexadentate 2,3,5,6-tetra(2-pyridyl)-pyrazine and their supramolecular organization

Reactions of 2,6-diisopropylphenyl phosphate (dippH2) with group 12 metal acetates [M(OAc)2•2H2O (M= Zn, Cd, Hg)] in the presence of hexadentate auxiliary N-donor ligand, 2,3,5,6-tetra-(2-pyridyl)pyrazine (tppz), produce binuclear tppz bridged complexes [M(tppz)(dippH)2]2.H2O (M= Zn (1), Hg (2)) and [Cd(tppz)(dippH)2.H2O]2.MeOH (3), as single crystals. Compounds 1–3 have been characterized by microanalysis and FT-IR, ESI-MS, and CP- MAS 31P NMR spectroscopy and thermal decomposition studies. The molecular structures of 1–3 have further been established by single crystal X-ray diffraction studies which reveal that all the three binuclear complexes exhibit extensive hydrogen bonding interactions due to the presence of uncoordinated POH groups and lattice water molecules, leading to the formation of 1D and 2D polymeric architectures.

Ionic liquid-assisted green solution approach for high-performance Cu2ZnSn(S,Se)4 thin film solar cells

In this research, a facile and environmentally friendly solution approach is developed to deposit Cu2ZnSn(S,Se)4 thin films by addition of n-butylammonium butyrate ionic liquid. n-Butylammonium butyrate plays a critical role in solution deposition of Cu2ZnSnS4 precursor thin film. We find that liquid n-butylammonium butyrate can dissolve a number of metal oxides, including Cu2O, ZnO, and SnO as well as various metal chlorides, metal nitrates and metal acetates. Smell-free Cu2ZnSnS4 precursor solution is synthesized by dissolving Cu2O, ZnO, SnCl2 and thiourea in an ethanol solution of n-butylammonium butyrate. Thermally degradable n-butylammonium butyrate can be completely removed by a low-temperature sintering process, forming high quality Cu2ZnSnS4 nanoparticle thin film. A power conversion efficiency of 8.79% is obtained by this facile and green solution approach.

Successful production of solution blow spun YBCO+Ag complex ceramics

YBCO fabrics composed of nanowires, produced by solution blow spinning (SBS) are so brittle that the Lorentz force produced by induced currents can be strong enough to damage them. On the other hand, it is known that silver addition improves the mechanical and flux pinning properties of ceramic superconductors. Thus, in this work, we show how we successfully obtained a polymeric precursor solution containing YBCO+Ag salts, which can be spun by the SBS route to produce ceramic samples. Yttrium, barium, copper, and silver metal acetates, and polyvinylpyrrolidone (PVP) (in a ratio of 5:1 wt [PVP:acetates]) were dissolved in a solution with 61.5 wt% of methanol, 12 wt% of propionic acid, and 26.5 wt% of ammonium hydroxide, together with 6 wt% of PVP in solution. Three different amounts of silver (10 wt%, 20 wt%, and 30 wt%) were used in YBa2Cu3O7−x. The TGA characterizations revealed a lowering of crystallization and partial melting temperatures by about 30 °C. SEM images show that after burning out the polymer, a fabric composed of nanowires of diameters up to 380 nm is produced. However, after the sintering process at 925 °C for 1 h, the nanowires shrink into a porous-like sample.

Hybrid Quinoline-Sulfonamide Complexes (M2+) Derivatives with Antimicrobial Activity

Two new series of hybrid quinoline-sulfonamide complexes (M2+: Zn2+, Cu2+, Co2+ and Cd2+) derivatives (QSC) were designed, synthesized and tested for their antimicrobial activity. The synthesis is straightforward and efficient, involving two steps: acylation of aminoquinoline followed by complexation with metal acetate (Cu2+, Co2+ and Cd2+) or chloride (Zn2+). The synthesized QSC compounds were characterized by FTIR and NMR spectroscopy and by X-ray diffraction on single crystal. The QSC compounds were preliminary screened for their antibacterial and antifungal activity and the obtained results are very promising. In this respect, the hybrid N-(quinolin-8-yl)-4-chloro-benzenesulfonamide cadmium (II), considered as leading structure for further studies, has an excellent antibacterial activity against Staphylococcus aureus ATCC25923 (with a diameters of inhibition zones of 21 mm and a minimum inhibitory concentration (MIC) of 19.04 × 10−5 mg/mL), a very good antibacterial activity against Escherichia coli ATCC25922 (with a diameters of inhibition zones of 19 mm and a MIC of 609 × 10−5 mg/mL), and again an excellent antifungal activity against Candida albicans ATCC10231 (with a diameters of inhibition zones of 25 mm and a MIC of 19.04 × 10−5 mg/mL).

Crystal structures and magnetic properties of two isomorphic nickel(II) and cobalt(II) coordination polymers-based nitrogen-heterocyclic tricarbolylate ligands

5-(3,4-Dicarboxylphenyl) picolinic acid (H3dppa) was applied as a new building block for the synthesis of two isomorphic coordination polymers, namely [Ni1.5dppa(H2O)3]n·nH2O (1), [Co1.5dppa(H2O)3]n·nH2O (2). Two compounds were generated by a hydrothermal self-assembly method using the corresponding metal(II) acetates and H3cppa ligand. Structure analysis reveals that compounds 1 and 2 are isomorphic both featuring a two-dimensional wave structure and are finally extended into the three-dimensional supramolecular architecture though hydrogen bonding interactions. Magnetic susceptibility measurements indicate that domain a weak ferromagnetic exchange coupling between the adjacent Ni(II) centers in 1, and a weak antiferromagnetic coupling between Co(II) ions in for 2.

Effect of cation size on alkali acetate-based ‘water-in-bisalt’ electrolyte and its application in aqueous rechargeable lithium battery

In this study, the properties of aqueous electrolytes based on alkali metal (Li, Na, K and Cs) acetates have been systematically investigated in order to figure out the effects of cations on the stability windows of corresponding electrolytes. At the same concentration of 7 m (molar-salt in kg-solvent), it is discovered that the stability windows of KOAc and CsOAc-based aqueous electrolytes are wider than those of LiOAc and NaOAc-based ones. This is due to enhanced polymer-like chains and weakened hydrogen bonds for the aqueous electrolytes with cations of larger size and higher mass. It is found that saturated 45 m CsOAc ‘water-in-salt’ electrolyte (WiSE) has an electrochemical stability window of 3.4 V, which is further mixed with 7 m LiOAc to form a mixed cation ‘water-in-bisalt’ electrolyte (WiBSE), prepared from a hydrated second salt (LiOAc•2H2O), delivering a stability window of 2.95 V. CR2032 coin cells are assembled based on the 45 m CsOAc + 7 m LiOAc WiBSE, with a VO2 nanobelt anode and LiNi0.5Mn1.5O4 hollow microsphere cathode, which deliver an operating voltage of 2.5 V. It exhibits a maximum specific discharge capacity of 68.1 mAh•g − 1 and relevant energy density of 114.8 Wh•kg−1 (calculated on the total mass of cathode and anode) under 1 C rate. At 4 C rate, the coin cell has a coulombic efficiency (CE) of about 99% reaching near 100% at certain cycles, and a desired capacity retention of 86.5% during the 1200 cycles. The crystal structure of the VO2 prepared in this study has been refined by GSAS+EXPGUI and it was found the lattice parameters are smaller than the conventional VO2 (B) phase although they share the same symmetry.

Solid-state conversion of metal oleate precursors for the preparation of LiNi1/3Co1/3Mn1/3O2 as cathode material for lithium-ion batteries

A solid-state conversion process for the preparation of LiNi1/3Co1/3Mn1/3O2 (NCM333) using metal oleate precursors was studied. The low melting points of metal oleate complexes result in a highly homogeneous mixture of Li-, Ni-, Co-, and Mn-oleates before calcination at a high temperature in a solid-state conversion process. The discharge capacity and capacity retention were assessed using a control sample prepared with metal acetate precursors. Cyclic voltammetry and electrochemical impedance spectroscopy showed larger cathodic and anodic peak currents and a lower charge transfer resistance for the coin cell with the cathode prepared from metal oleates than for the cell with the cathode prepared from metal acetates. The superior electrochemical properties of the NCM333 cathode prepared by the solid-state conversion process suggested in this study are attributed to the formation of a perfect $$R\overline 3 m$$ layered structure with a low degree of cation mixing.

(Invited) Controlling the Electronic Energy Structure of ZnSe-AgInSe2 Solid Solution Nanorods for Visible-Light-Driven Photocatalytic H2 Evolution

Intense research efforts have been focused on developing high-quality semiconductor nanocrystals (NCs) containing no toxic elements. Especially I-III-VI2 ternary NCs, such as CuInS2 and AgInS2, exhibiting the quantum size effect, have attracted much attention for the application to solar energy conversion systems, because they have large absorption coefficients in the visible wavelength region and their electronic energy structure could be controlled by modifying their size, shape, and chemical composition. Recently we have successfully prepared anisotropic-shaped NCs of ZnS-AgInS2 solid solution. Their photocatalytic H2 evolution activity could be controlled by the chemical composition as well as by the particle size [1], and increased with particle morphology in the order of rice < sphere < rod [2]. To efficiently utilize solar light for photocatalytic reactions, near-IR-responsive NCs have been intensively developed. In general, the Eg of I-III-VI semiconductor decreases with use of Se as group IV element in place of S. Thus, in this study, we prepare rod-shaped NCs composed of less-toxic ZnSe-AgInSe2 solid solution ((AgIn)xZn2(1-x)Se2, ZAISe(x)) and report their photocatalytic activity for H2 evolution.Rod-shaped ZAISe(x) NCs with different x values were synthesized by thermal decomposition of corresponding metal acetates and selenourea in a mixture solution of oleylamine and dodecanethiol at 250 oC. The chemical composition of resulting NCs, that is, x value, could be controlled by varying the fraction of Zn(OAc)2 in metal precursors, in which the NCs had almost stoichiometric composition. The length of nanorods decreased from ca. 116 to 8.2 nm with an increase in the x value, while the width of nanorods increased from ca. 3.7 to 6.9 nm. The absorption onset of ZAISe(x) NCs was blue-shifted from ca. 900 to 500 nm with a decrease in the x value, that is, with an increase in the Zn fraction.The photocatalytic activity of ZAISe(x) NCs was investigated for H2 evolution as a model reaction. The ligands modified on the nanocrystal surface were changed from dodecanethiol to mercaptopropionic acid to improve the dispersibility of NCs in an aqueous solution. The irradiation to ZAISe(x) NCs suspended in an aqueous solution containing Na2S and Na2SO3 as hole scavengers was carried out using Xe lamp light (λ> 350 nm). With elapse of light irradiation, the amount of H2 evolved linearly increased, regardless of kinds of ZAISe(x) NCs. The H2 evolution rate was remarkably dependent on the composition of ZAISe(x) NCs: A volcano-type dependence was observed between the H2 evolution rate and the energy gap (Eg) of ZAISe(x) NCs. The highest photocatalytic activity was obtained for rod-shaped ZAISe(0.5) NCs with Eg of 1.65 eV. This behavior can be explained by the changes in both the electronic energy structure of ZAISe NCs and the amount of photon absorption with the chemical composition. Furthermore, the rod-shaped ZAISe(x) NCs exhibited a higher photocatalytic activity than that of spherical ones with similar Eg.

(Invited) Hot Hole Transfer from Zn-Ag-in-Te Nanocrystals Photo-Excited with High-Energy Photons

Semiconductor nanocrystals (NCs), so-called quantum dots, exhibit unique size-dependent physicochemical properties different from bulk materials and have attracted intense attention for the application to solar light energy conversion systems. Since the relaxation rates of carriers in highly excited states are remarkably reduced by the discrete energy levels of semiconductor NCs due to the phonon bottleneck effect, unique photoresponses of semiconductor NCs are induced by the absorption of photons with energy higher than the energy gap (Eg) of NCs. For example, by extending the relaxation time of hot carriers, it was possible to transfer excess kinetic energy before releasing it as heat. Thus, next-generation solar cells of outstandingly high efficiency beyond the Shockley-Queisser limit can be developed if photogenerated carriers are harvested from a semiconductor NC without energy loss of incident photons.I-III-VI2 semiconductor-based nanoparticles, such as CuInS2 or AgInS2 and their solid solution with ZnS, have been intensively studied as a visible-light-driven photocatalyst because of their excellent optical properties (e.g. direct band gaps in the visible-light region, and large absorption coefficients). Recently, we prepared ZnTe-AgInTe2 solid solution ((AgIn)xZn2(1-x)Te2: ZAITe) NCs with a rod shape, the Eg of which was enlarged from 1.20 to 1.60 eV with an increase in Zn content.1 ZAITe NCs exhibited a narrow band-edge PL peak with high QYs, and the PL peak wavelength was tunable in the near-IR wavelength region depending on their energy gap (Eg). These NCs are expected to act as a photosensitizer for near-IR light, but their photoelectrochemical properties have not been investigated. In this study, we clarified the electronic energy structure of ZAITe NCs for utilization as a photosensitizer and then investigated the photoelectrochemical properties of ZAITe NC-immobilized photoelectrodes.2 Since photons in the visible light region have much larger energies than the Egs of ZAITe NCs, it is important to examine the influence of photogenerated carriers with excess energies on the photoelectrochemical properties of ZAITe NCs with the goal of application to photovoltaic devices.ZAITe NCs were synthesized by a thermal reaction of corresponding metal acetates and a Te precursor in 1-dodecanethiol at 180°C for 180 min. TEM observations revealed that rod-shaped NCs with width of ca. 4 nm and length of ca. 11 nm were formed regardless of chemical composition of particles, that is, the x value. We revealed the electronic energy structures of ZAITe NCs with the compositions of x= 1.0, 0.75, and 0.5, the Eg values of which were 1.20, 1.27, and 1.46 eV, respectively. The band-edge potentials of conduction band (ECB) and valence band (EVB) were negatively and positively shifted with an increase in the Eg of NCs, the degree being more remarkable for the change in ECB.The photocurrent-potential curves of ZAITe NCs-immobilized on ITO electrode with thickness of less than one monoparticle layer resembled a p-type semiconductor photoresponse, but the behavior was remarkably different from those of ZAITe NC multilayer films: The onset of cathodic photocurrent was shifted more positively than that of EVB of ZAITe NCs and the photocurrent generation efficiency was significantly enlarged, when photons of energy higher than ca. 2.5 eV were irradiated. The photocurrent onset potential was also dependent on the energy of irradiaited photons for thin ZAITe NC films. Irradiation of photons with lower energy than 2.43 eV gave the onset potential at around 0 V vs. Ag/AgCl, being comparable to the EVB of ZAITe NCs with x = 0.75, -0.05 V vs. Ag/AgCl. On the other hand, the increases of photon energy to 2.95 and 3.40 eV gave more positive onset potentials of 0.1 and 0.3 V vs. Ag/AgCl, respectively. Thus we conclude that the excitation with photons of > ca. 2.5 eV enabled the direct injection of hot holes from ZAITe NCs into ITO electrodes, resulting in enhancement of the photocurrent generetion efficiency of ZAITe NCs. Reference 1. T. Kameyama, et al., J. Mater. Chem. C, 2018, 6, 2034.2. T. Kameyama, et al., ChemNanoMat, 2019, 5, 1028.

Metal-containing ceramic nanocomposites synthesized from metal acetates and polysilazane

Metal-containing (Mn, Fe, Co, Cu, Zn and Ag) polysilazane precursors are synthesized via one-step chemical reaction of metal acetates with poly(vinyl)silazane (Durazane 1800) at room temperature under argon atmosphere. The ATR-FTIR spectra of the synthesized metal-containing precursors reveal that the metal acetates used in the synthesis catalyze the hydrosilylation reaction between -Si-H and -Si-CHCH2 groups in polysilazane. The XPS and XRD characterizations indicate that the metallic phase is directly generated in precursors after the reaction of Durazane 1800 polymer with Fe(CH3COO)2, Co(CH3COO)2·4H2O, CuCH3COO, Cu(CH3COO)2, AgCH3COO. Ceramic nanocomposites containing either metal or metal silicide are obtained after the pyrolysis of the synthesized metal-containing precursors at 700 ​°C and 1100 ​°C under argon atmosphere.

Mixed metal oxides in synergy at nanoscale: Electrospray induced porosity of in situ grown film electrode for use in electrochemical capacitor

A heterogeneous film electrode with mixed metal oxides of nickel and cobalt constituting the active layer is developed by first electrospraying metal acetate precursors on nickel foam, followed by calcination. The formation of unique cubic phases of nickel oxide (NiO) and cobalt oxide (Co3O4) are confirmed through X-ray diffraction. The growth of two oxides in nanoscale is confirmed from high-resolution transmission electron microscopy, whereas the images from scanning electron microscope show synergistic growth leading to three dimensional porosity. The synergy is further demonstrated from the areal capacity of 267 mC cm−2 at 1 mA cm−2 for mixed oxide electrode, which is much higher than the respective values for pure NiO film (124 mC cm−2), and Co3O4 film (174 mC cm−2) electrodes. The faradaic behaviour of Co3O4 film electrode in cyclic voltammetry and chronopotentiometry scans is significantly modified to a more capacitive charge transfer due to the presence of NiO, resulting in better rate capability. The electrochemical performance of film electrodes is augmented utilizing hybrid mode, where in situ grown carbon film based on electrospray coating of resorcinol formaldehyde on nickel foam serves as counter electrode. The hybrid cell delivers specific energy and specific power to the extent of 22.7 Wh kg−1, and 2.8 kW kg−1 respectively, with the capacitance retention of 89% after 2000 cycles at 10 mA cm−2.

A Co(salen)-based metal–organic framework: suppresses breast cancer cell proliferation, migration and invasion

In this research, by using the metalloligands approach, a new heterometallic–organic framework has been successfully prepared by one-step synthesis of reacting H4L with metal acetate in water and EtOH mixed solvent, and its chemical formula is {CdNa2(H2O)3[(CoL)2Na(OH)(H2O)]}·6H2O (1, H4L = 3,3′-((1E,1′E)-(cyclohexane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(4-hydroxybenzoic acid)). In the biological study, the CCK-8 method was exploited to determine the survival rate of MCF7 breast cancer cells after compound treatment. The plate colony formation test was used to confirm the inhibitory effect of this compound on the proliferation of MCF7 cancer cell. Besides, the Annexin V-FITC/PI assay were performed to evaluate the apoptosis of compound-treated MCF7 cells in flow cytometer, the intracellular ROS level was also measured via Reactive Oxygen Species Assay Kit in this study.

Charge Reduction of Membrane Proteins in Native Mass Spectrometry Using Alkali Metal Acetate Salts

Native mass spectrometry (MS) provides the capacity to monitor membrane protein complexes and noncovalent binding of ligands and lipids to membrane proteins. The charge states produced by native MS of membrane proteins often result in gas-phase protein unfolding or loss of noncovalent interactions. In an effort to reduce the charge of membrane proteins, we examined the utility of alkali metal salts as a charge-reducing agent. Low concentrations of alkali metal salts caused marked charge reduction in the membrane protein, Erwinia ligand-gated ion channel (ELIC). The charge-reducing effect only occurred for membrane proteins and was detergent-dependent, being most pronounced in long polyethylene glycol (PEG)-based detergents such as C10E5 and C12E8. On the basis of these results, we propose a mechanism for alkali metal charge reduction of membrane proteins. Addition of low concentrations of alkali metals may provide an advantageous approach for charge reduction of detergent-solubilized membrane proteins by native MS.

Synthesis and Antimicrobial Activity of Metal-Containing Linseed Oil-Based Waterborne Urethane Oil Wood Coatings

In this study, the antimicrobial agents of mono(hydroxyethoxyethyl)phthalate (M(HEEP)2) with different metal of M = Zn, Mn, Pb, and Ca were synthesized from diethylene glycol (DEG), phthalic anhydride (PA), and divalent metal acetates including calcium acetate, zinc acetate, manganese acetate, and lead acetate, respectively. The waterborne urethane oil (WUO) dispersions synthesized from linseed oil, diisocyanates (hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI)), dimethylolpropionic acid at NCO/OH molars of 0.9, by acetone processing method were described as in our previous report. The M(HEEP)2 antimicrobial agents as well as the commercial nanosilver powder were added into WUO dispersions as the antimicrobial coatings. The effects of various antimicrobial agents and dosages (0.0, 0.2, 0.6, 0.8, 1.0, 2.0, and 4.0 phr) on antimicrobial activity of WUO films against gram-negative bacterium of Escherichia coli, gram-positive bacterium of Staphylococcus aureus, brown-rot fungus of Gloeophyllum trabeum, and white-rot fungus of Lenzites betulina were assessed. In addition, the film properties of the best antimicrobial WUO coatings were also examined. The results showed that the antimicrobial agents of mono(hydroxyethoxyethyl) phthalate M(HEEP)2 (M = Zn, Mn, Pb, and Ca) powders should certainly be synthesized by FTIR, 1H-NMR, 13C-NMR, and energy-dispersive X-ray spectroscopy (EDS) identifications and the yields of them were 43–55%. The results also revealed that the WUO film synthesizing with HDI films containing Zn(HEEP)2 of 2.0 phr and Pb(HEEP)2 of 0.4 phr had the best antibacterial activity for E. coli and S. aureus, respectively. The IPDI films containing Zn(HEEP)2 of 1.0 phr had the best antibacterial activity for both E. coli and S. aureus. For antifungal activity, the WUO film synthesizing with HDI films containing Pb(HEEP)2 of 0.8 phr and Zn(HEEP)2 of 2.0 phr as well as IPDI films containing Mn(HEEP)2 of 0.2 phr and Zn(HEEP)2 of 4.0 phr had the best performances against G. trabeum and L. betulina, respectively. Comparing with commercial nanoAg powder, the Zn(HEEP)2 and Pb(HEEP)2 had a superior antifungal efficiency for G. trabeum and L. betulina, while it had a slightly inferior efficiency in the antibacterial activity for E. coli and S. aureus. On the properties of WUO films, adding metal-containing antimicrobial agents could slightly enhance the thermal stability, but lowered the gloss of all films, however, the Tg value increased for HDI film and decreased for IPDI film. In addition to this, they had no significant difference in the film properties including hardness, impact resistance, bending resistance, adhesion, mass retention, and light-fastness between the WUO films with and without adding antimicrobial agents.

The ozonolytic synthesis of acetophenone - a by-product for the production of drugs of calming effect

Acetophenone is an important by-product for the manufacture of drugs of calming effect. Known methods of its production don't have the future due to technological complexity, harsh synthesis conditions and low processing coefficients of raw materials. Therefore, the development of low-waste, low-temperature synthesis of acetophenone with ozone is an urgent task. The purpose of the work was to study the kinetic regularities of the reaction of ozone with ethylbenzene in acetic acid and to create the ozonolytic synthesis of acetophenone. Materials and methods. Glacial acetic acid of “Sigma” firm of qualification Ch. P.; ethylbenzene, acetophenone of “Acros Organics” firm of qualification “Ch. P.”; acetates of metals of qualification “Ch. P.” were applied. The concentration of O 3 in the gas phase was determined by a spectrophotometric absorption method in the range of 254–290 nm on spectrophotometer SF-46, which was designed to measure the transmittance of liquid and solid transparent substances in the spectral range from 190 to 1100 nm. Identification of the components of the reaction mass and their quantitative analysis in solution was performed by gas-liquid chromatography. Results. The kinetic regularities of the oxidation of ethylbenzene with ozone in a solution of glacial acetate have been investigated. It is shown that ozone occurs at a temperature of 15 °C, mainly by the aromatic ring. The addition into the catalyst system - manganese (II) acetate has increased the selectivity of oxidation on the side chain from 34.0 to 87.7 %. Acetophenone (76.5 %) and methylphenylcarbinolacetate (11.2 %) are formed as the main products. Conclusions. Ozonation of ethylbenzene in acetic acid was taken place mainly on the aromatic ring, and it was not possible to obtain acetophenone in high yield. The addition of transition metals allowed to be directed the process along the side ring to form 76 % acetophenone.

Two pentanuclear clusters: synthesis, crystal structures, luminescent and magnetic properties

Reactions of N,2-dihydroxy-3-methoxybenzamide (H3L) with transition metal acetates in the presence of pyridine and/or 2,2′-bipyridine under solvothermal conditions give two pentanuclear complexes, [Zn5L2(CH3COO−)4(py)3] (1) and [Co5L2(CH3COO−)4(py)(2,2′-bipy)2] (2). Photoluminescence studies indicate strong purple emission for 1 in the solid state at room temperature. Variable-temperature dc magnetic susceptibility studies of 2 reveal that antiferromagnetic CoII···CoII exchange interactions exist in 2.

One step synthesis Pd/NiO@rGO/CNTs nanocomposite for energy storage as supercapacitor application

In this study, graphite oxide was reduced into reduced graphene oxide nanosheets (rGO NSs) by microwave with metal acetate of nickel and palladium to form the rGO-carbon nanotubes (CNTs) containing palladium (Pd) and nickel oxide (NiO) nanocomposite (Pd/NiO@rGO/CNTs nanocomposite). The synthesized nanocomposite presents remarkable performance for supercapacitor application especially in stability, exhibiting specific capacitance of 24 F/g at scan rate of 10 mV/s and excellent capacitance retention of 95% after 500 consecutive CV cycles at scan rate of 100 mV/s.

A study of structural and dielectric properties of Ba2+ doped CH3NH3PbI3 crystals

An understanding of the effects of doping in lead perovskites may allow for improved solar cell performance or reduction in toxicity of the materials used. Ba2+ doped CH3NH3PbI3 (CH3NH3Pb1−xBaxI3 with x = 1%, 5% and 10%) are successfully synthesized by cooling down a concentrated aqueous solution containing HI, CH3NH2 and metal acetates and their properties are investigated using x-ray diffraction, differential scanning calorimetry, and impedance spectroscopy (IS). No new structures are formed upon doping with Ba2+ ions, however the lattice expands. The IS measurements show a strong increase in the conductivity and dielectric constants of the doped crystals. The conductivity arises mainly from vacancy mediated iodide ion (I−) migration and the increase in ionic conductivity with dopants is ascribed to increased defect formation due to lattice distortion. In addition, the bulk dielectric constant increases with increasing Ba2+ dopant. The increase in the dielectric constant is consistent with ordering of CH3NH3 dipoles resulting from distortions of the Ba sites in the lattice. The temperature dependence of the dielectric constants is attributed to thermal effects on the orientation of CH3NH3 molecules.

Synthesis, spectral-characterization, biological and DFT studies of mixed ligand metal(II) complexes of 1,10-phenanthroline bearing 2-aminothiazole moiety

The Schiff base ligand L is developed from furan-2-carboxaldehyde, 4-aminoantipyrine together with 2-aminothiazole. The mixed ligand complexes are developed from the condensation of above Schiff base ligand L , 1,10-phenanthroline as well as metal(II) acetates of Co(II), Ni(II), Cu(II), and Zn(II). The newly produced compounds were characterized using molar conductance, elemental analysis, XRD, mass, UV-Vis, 1H NMR as well as IR spectral techniques. The X band ESR of [CuLphen] complex was recorded at 300 and 77 K. Geometry and Mulliken charge distribution of the L were studied using Density functional theory (DFT). In vitro biological analysis of L and its [CoLphen], [NiLphen], [CuLphen] as well as [ZnLphen] complexes were studied against bacterial variety such as Pseudomonas aeruginosa, Escherichia coli as well as Staphylococcus aureus. The fungal varieties include Aspergillus niger and Candida albicans. The potent DNA cleavage activities of L as well as its complexes were evaluated.

Features of improved capacity at high discharge rate of K-doped Li-rich cathodes for LIBs

Li-rich oxides are one of the most promising cathode materials for the new generation of lithium-ion batteries (LIBs). This work describes the preparations of Li-rich cathode materials with composition Li1.20Ni0.13Co0.13Mn0.54O2 and the potassium – doped material Li1.15K0.05Ni0.13Co0.13Mn0.54O2. The oxides are synthesized from acetates of metals by sol-gel synthesis followed by high-temperature annealing. All materials are characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) with elemental analysis by EDX and elemental mapping. We also measure granulometric compositions of the powders by laser particle size analyzer. The samples were tested as cathode material in half-cells with lithium metal as the anode. The results of these electrochemical tests are presented in the article. Potassium – doped Li-rich oxides show more than 260 mAh/g discharge capacity, at current rate 0.1C and higher discharge capacity after increasing discharge current.