Ratio Of Metal Ions Research Articles

Biogenic synthesis of shape-tunable Au-Pd alloy nanoparticles with enhanced catalytic activities

Herein, we report the synthesis of bimetallic Au-Pd and monometallic Au and Pd nanoparticles (NPs) by successive reduction of the respective metal ions using phytochemicals in the form of plant extract under ambient conditions. Phytochemicals act both as reducing and shape directing agent for metal and alloy NPs. The synthesized nanostructures were characterized by different microscopic, spectroscopic and diffractometric techniques. Microscopic results confirmed that the shape and size of the alloy nanostructures can be tuned by varying the concentration ratio of metal ions in the reaction medium. Energy dispersive X-ray and X-ray photoelectron spectroscopic analysis confirmed the formation of bimetallic Au-Pd nanostructures. The purity and crystalline properties were studied by X-ray diffraction technique. UV–vis spectra were recorded to study the optical properties of the synthesized nanostructures. Further, we tested the catalytic activity of both the monometallic and bimetallic alloy nanostructures in borohydride reduction of hazardous organic dye molecules in aqueous medium. The bimetallic alloy NPs exhibit better catalytic activities compared to their respective monometallic nanoparticles.

Model forecasting of phase composition of electrolytic alloys Co-Ni-Mn (part 1)

With the help of four criteria for phase formation, a model forecasting of the phase composition of electrolytic alloy Co-Ni-Mn was carried out; the expected phases were calculated. The boundaries of the chemical content of the metal-solvent (Co) in these phases are determined, depending on the ratio of metal ions in the electrolyte of deposition. Model forecasting of the phase composition of Co-Ni-Mn alloys makes it possible to predict the type and number of Co phases (hexagonal close-packed - HCP-α-Co, face-centered cubic - FCC-β-Co) depending on the mole fraction of the solvent metal (Co). In the first approximation, the forecast allows one to determine the phase and chemical composition of the coating, which corresponds to the specified operational properties.

Structure and magnetic properties of Co-Ni-Mn alloy coatings (part 2)

Using the method of high-frequency alternating current (HFAC), based on the preliminary model forecasting of the ratio of metal ions in the electrolyte and the phase composition of the coating, Co-Ni-Mn alloy precipitates with the specified magnetic properties are obtained. It is shown that precipitation with a hexagonal close-packed α-Co phase has the highest coercive force. The presence of a free phase in a small amount (2.1 - 2.6% of weight) of Mn increases the ferromagnetic properties of films due to the domain structures with a poorly defecting α-Mn crystal lattice. The adjustable amount of the amorphous Co(OH)2 phase provides the nanostructure dimensions of the crystals.

A novel biphenolic ligand for selective Mg2+ and Zn2+ ions sensing followed by colorimetric, spectroscopic and cell imaging methods

The (E)-2-((2-hydrohy-5-methylphenylimino) methyl) phenol ligand was synthesized. The receptor was characterized by IR, 1H and 13C NMR and CHN analysis. The ligand exhibits colorimetric and fluorometric sensing of Zn2+ and Mg2+ ions in semi-aqueous medium (DMSO-H2O). The receptor was tested with series of transition metal ions (Cr2+, Fe2+, Ni2+, Co2+, Cu2+, Zn2+) and heavy metal ions (Sn2+, Pd2+, Ce2+, Hg2+, Cd2+) and the essential human body elements like Ca2+, Mg2+, Na+ and K+ ions. The naked eye colorimetric sensing was absorbed only for Zn2+ and Mg2+. Both ions (ZnCl2 and MgCl2 in H2O), when added to the colorless solutions of the receptor of about 1 equivalence in incremental additions turn the solution into bright turmeric yellow. All other ions remain inactive, in colorimetric sensing. Further the Zn2+ and Mg2+ ions were probed by absorption and emission spectroscopy through incremental addition of respective metal ions. The in-situ deprotonation of the ligand on both Mg2+ and Zn2+ ions binding was confirmed by 1H NMR titration studies. The imino nitrogen of the receptor is not coordinated to the metal ions. The Job's plot studies reveal the 1:2 binding ratio of metal ions to the receptor. The high fold fluorescence output on metal ions binding was positively used to sense the Zn2+ and Mg2+ ions, separately and together in HeLa cancer cells through cell imaging.

Effect of carbon coating on electrochemical performance of LiFePO4 cathode material for Li-ion battery

Pristine LiFePO4 (LFP) and carbon-coated LiFePO4 (LFP/C) are synthesized by sol-gel process using citric acid as a carbon precursor. LFP/C is prepared with three different stoichiometric ratios of metal ions and citric acid, namely 1:0.5, 1:1, and 1:2. Prepared LFP and LFP/C powder samples are characterized by X-ray diffractometer, field emission scanning electron microscope, transmission electron microscope, and Raman spectrophotometer. Electrochemical performances of pristine and carbon-coated LFP are investigated by charge-discharge and cyclic voltammetry technique. The results show that LFP/C (1:1) with an optimum thickness of 4.2 nm and higher graphitic carbon coating has the highest discharge capacity of 148.2 mA h g−1 at 0.1 C rate and 113.1 mA h g−1 at a high rate of 5 C among all four samples prepared. The sample LFP/C (1:1) shows 96% capacity retention after 300 cycles at 1 C rate. The decrease in discharge capacity (141.4and 105.9 mA h g−1 at 0.1 and 5 C, respectively) is observed for the sample LFP/C (1:2). Whereas, pristine LFP shows the lowest discharge capacity of 111.1 mA h g−1 at 0.1 C and capacity was decreased very fast and work only up to 147 cycles. Moreover, cyclic voltammetry has also revealed the lowest polarization of 0.19 V for LFP/C (1:1) and the highest 0.4 V for pristine LFP.

Aqueous synthesis of functionalized copper sulfide quantum dots as near-infrared luminescent probes for detection of Hg2+, Ag+ and Au3+

Stable water-soluble copper sulfide(Cu2S) quantum dots(QDs) with near-infrared emission were synthesized using N-acetyl-L-cysteine(NAC) as a modifier in aqueous solution and nitrogen atmosphere at room temperature. The product was characterized by TEM, XRD, XPS, FT-IR, FL and UV-VIS spectrometers. Effects of preparation conditions such as pH values, the molar ratio of reactants, temperature, and metal ions on the fluorescence properties of Cu2S QDs were discussed. Under optimal conditions, the prepared Cu2S QDs with average diameter about 2–5 nm show a near-infrared emission at 770 nm with the excitation wavelength of 466 nm, and have a good detection sensitivity for ions of Hg2+, Ag+ and Au3+, based on the characteristic of fluorescence quenching. The fluorescence quenching mechanism was proposed via electron transfer with cation exchange, which based on the theory of Hard-Soft-Acid-Base (HSAB) and Ksp value of metal–sulfide.

Mass Transfer Mechanisms in Solid Electro Deposition

Copper plating is generally used for the fabrication of printed circuit boards of electronic devices. The patterning is carried out by masking with insulator for the partial plating on the substrate. It is desirable to develop a new alternative technology that takes environmental issues into consideration because the partial plating with a mask involves very complicated processes and wastewater treatment. Solid Electro Deposition (SED) method with the solid electrolyte membrane was reported by Yanagimoto et al.1) as the way to resolve the problem. The SED can be performed by a simple electrochemical cell in which the solid electrolyte membrane is sandwiched by counter and working electrodes. Imposition of voltage between two electrodes enables electrodeposition on the working electrode. The advantages of SED are written as follows. ・The electrochemical cell is very simple because the electrolyte is solid. ・The post-processing is also simple． ・It can be high-rate plating because the driving force of mass transfer of reactant is migration. Among these advantages, the principle for high-rate plating by SED is explained below. Figure 1 shows the conceptual diagrams of mass transfer of cupric ions on electrode surface in two electrolytes. The charge transfer rate increases depending on the overvoltage in the case of plating in liquid electrolyte. However, the concentration polarization occurs on the electrode surface when the charge transfer rate is higher than the mass transfer rate of reactant. In this case, the driving force of mass transfer in electrolyte is normally diffusion. On the other hand, the mass transfer of reactant is dominated by migration in the SED if the transport ratio of metal ions in the solid electrolyte is unity. In this condition, the charge transfer rate becomes equal to the migration rate and the concentration polarization of reactant in the vicinity of the electrode does not occur, even if the charge transfer rate is increased. Therefore, it is possible to realize high-rate plating because diffusion is not rate-limiting process. We report the relationship between mass transfer mechanisms in solid electrolyte membrane and potential-current curves and establish the theory of high-rate copper plating by the SED. Reference: 1) K. Akamatsu, Y. Fukumoto, T. Taniyama, T. Tsuruoka, H. Yanagimoto, H. Nawafune, Langumuir, 27, 11761-11766 (2011). Figure 1

Evaluation of corrosion resistance of electrodeposited nanocrystalline Ni–Fe alloy coatings

Nickel–iron alloys with a compositional range of 24–80 wt-% iron were electrodeposited on a copper substrate from a sulphate-based bath and using a stirring rate of 100 rev min−1. The effect of applied current density and Ni2+/Fe2+ metal ion ratio of plating bath on the properties of alloy coatings was examined. Crystal structure and grain size of Ni–Fe alloy coatings were investigated using X-ray diffraction technique. Field emission scanning electron microscopy and energy dispersive X-ray spectroscopy were used to analyse the surface morphology and chemical composition of coatings. Microhardness test was applied to evaluate the hardness of the coatings. Finally, the electrochemical behaviour of the Ni–Fe alloy coatings was studied by a polarisation test in 10 wt-% H2SO4 solution. Results revealed that current density and plating bath composition had a strong effect on the characteristics of coatings. As the iron content of alloys produced increased, their corrosion resistance improved with the best corrosion resistivity being achieved at a metal ion ratio of 0.5 and applied current density of 2.5 A dm−2.

Structural characterization of a sodium perchlorate−acridino-18-crown-6 ether complex

This paper describes the X-ray crystal structure of a complex of acridino-18-crown-6 ether (S,S)-2 and sodium perchlorate. The structure shows a homodimer in the crystal and suggests the potential for π–π bonded interactions between the monomers. The average distance of the two tricyclic units (3.49 ± 0.1 A) may indicate a considerably strong π–π interaction. Fluorescence titration was performed in order to determine the stoichiometry and stability constant (K s) of the sodium ion-(S,S)-2 complex. Based on the global fitting of the fluorescence spectra, we suggest the formation of a complex with 1:1 ligand to metal ion ratio, and the logK value determined by nonlinear regression analysis was 5.23.

The fluorescent property of 3-[(2-hydroxy-1-naphthyl) methylideneamino]benzoic acid and its application as fluorescent chemosensor for Hg2 + and Al3 + ions

This manuscript studies the fluorescent property of 3-[(2-hydroxy-1-naphthyl)methylideneamino]benzoic acid (H2L). Fluorescent spectra show that in different solvents, H2L displays different fluorescent properties, which can be attributed to the interaction between the solvents and H2L. Further study indicates that H2L exhibits a highly selective and sensitive recognition for Hg2+ ions in dimethylsulfoxide (DMSO), Al3+ ions in methanol and N,N′-dimethylformamide/water (DMF/H2O, 1/1, v/v). The bonding modes and bonding ratio of H2L and metal ions in different solvents are explored by Job's plot, 1H NMR titration, and electrospray ionization mass spectrometry (ESI-MS). The probable mechanisms were discussed.

Fabrication of BaZr1-XYxO3 Powder by Freeze Drying Method

BaZr1-xYxO3 is an attractive electrolyte material for low operating temperature SOFCs and SOECs because of its high proton conductivity at temperature less than 600 oC and good chemical stability under CO2 and steam atmospheres. However, its high synthetic temperature more than 1100 oC and the high sintering temperature more than 1,600 oC to get a dense electrolyte membrane cause mismatch of the shrinkage behavior and reaction with other SOFC or SOEC component materials at the fabrication process. Therefore, in this paper, reducing the synthesizing temperature of BaZr1-xYxO3 powders by freeze dry method has been tried. In the freeze dry process, Ba(NO3)2, ZrO(NO3)2 nH2O, Y(NO3)3 nH2O were chosen as low materials. The hydration numbers of ZrO(NO3)2 nH2O and Y(NO3)3 nH2O were measured by using a differential thermogravimetric analyzer. These nitrates were mixed to produce solution with the molar ratio of metal ions what we desired. The solution was atomized and frozen rapidly by using liquid nitrogen to avoid segregation. The frozen solution was dried under vacuum condition at temperature of about -40 oC. After finishing sublimation, obtained frozen powder was heated and synthesized at the temperatures of 600 to1000 oC. As a result of X-ray diffraction analysis and energy dispersive X-ray spectrometry, it is clarified that BaZr1-xYxO3 can be synthesized at 800 oC which is lower more than 300 oC than conventional synthetic temperature. We are to report the possibility of reducing the sintering temperature of BaZr1-xYxO3 by using obtained powders and properties of the sintered BaZr1-xYxO3 such as the conductivity.

Impact of molar ratio of total metal ions to precipitant on YAG:Ce nanophosphors synthesized by reverse titration coprecipitation

Abstract Systematic study on the impact of the pH value was performed in the preparation of YAG:Ce nanophosphor powders by reverse titration method. Therefore, we used wider range of the pH values from 5.0 to 8.3 for the synthesis, correlating closely with ratio R of the total metal ions to precipitant ammonium hydrocarbonate in the solution from 1:3 to 1:9. The calcination temperatures of 1050 °C and 1300 °C were tested for the crystallization of YAG:Ce nanophosphors. Acidic condition is more preferable for improved YAG:Ce nanophosphors through XRD spectra analysis for the type of crystals and the crystal size. The molar ratio Y 3+ /Al 3+ in the precursor was controlled at the level of R =1:3 to keep the stoichiometric ratio of YAG:Ce. SEM images showed the YAG:Ce nanophosphors prepared at acidic condition having smaller crystal size and improved dispersibility. Fluorescence spectrum displayed much stronger emission at R =1:3. The molar ratio R is a vital factor to control the quality of the YAG:Ce powders. The nanophosphors prepared at R =1:3 possessed the best fluorescence emission.

Effect of metal ion location in reaction medium on formation process and structure of PtCu–CuO nanoparticles supported on carbon and γ-Fe2O3

ABSTRACTThe process of nanoparticle formation by radiochemical synthesis in a heterogeneous system has been investigated considering the effects of the metal ion location in the reaction medium. PtCu nanoparticles supported on carbon and γ-Fe2O3 were synthesized using a high-energy electron beam. The metal ions in the precursor were categorized as those dissolved in solution, adsorbed on support, and precipitated. The ratio of metal ions in the solution was varied prior to the electron beam irradiation and its effects on the synthesized particle structures were examined. The nanoparticles were characterized by inductively coupled plasma-atomic emission spectrometry, transmission electron microscopy, X-ray diffraction, and X-ray absorption spectroscopy. A PtCu alloy and CuO were immobilized on the support in all the samples. The PtCu alloy nanoparticle composition depended on the Cu ion content in the solution. The nanoparticle formation mechanism could be explained using the obtained results. Metal ions present in the solution resulted in formation of the alloy. The adsorbed ions also contributed to the alloy formation by desorbing from the support when irradiated. On the other hand, alloy formation with Pt from the precipitated Cu ions was found to be difficult.

Ultrasound findings in asymptomatic patients with modular metal on metal total hip arthroplasty.

The use of metal-on-metal and modular total hip arthroplasty is associated with potentially serious local and systemic complications. The primary aim of this study was to identify the prevalence of a pseudotumor in asymptomatic patients with a particular metal-on-metal hip prosthesis after a minimum follow-up of 5years using ultrasound evaluation. A secondary purpose was to identify associations between the presence of pseudotumor and serum metal ion levels following implantation. We prospectively evaluated data collected from 36 asymptomatic patients who underwent implantation of a Profemur Z metal-on-metal total hip arthroplasty from January 2004 to January 2010. Serum metal ion levels were collected in 2012 and 2015. Hip ultrasounds were performed in 2015. Pseudotumors were found in 7/36 patients (19.4%). The average pseudotumor size measured 38.2cm3 (range 7.35cm3-130.81cm3). Elevated metal ion levels were found in all patients at all time points. No statistical correlation was found between the presence of pseudotumor and patient age, age of the implant, component design, and any of the serum metal ion levels or ratios. One in every five asymptomatic patients with metal-on-metal implants was found to have a periarticular pseudotumor. There was no dose-dependent relationship found between elevated serum metal ion levels and the development of a pseudotumor. Our findings suggest that in patients with known elevated metal ion levels, continued monitoring of ion levels may not be a reliable predictor of pseudotumor formation, and ultrasound surveillance can and should be routinely used to document the presence and progression of pseudotumor.

Formation of sol-gel based Cu2ZnSnS4 thin films using ppm-level hydrogen sulfide

This study reports the preparation of copper zinc tin sulfide (Cu2ZnSnS4 or CZTS) thin films using parts-per-million (ppm) level of hydrogen sulfide (H2S) gas as opposed to high percentage level of H2S (e.g., ≥5%) in many other studies. Sol-gel technique was adopted for the preparation of metal oxide films from precursor solutions with different ratios of Cu, Zn, and Sn metal ions. Sulfurization process was carried out in tube furnace using 100ppm H2S balanced by hydrogen at different temperatures. Generally, it was observed that the sulfur content of the thin films obtained showed strong dependence on the sulfurization temperature. Samples sulfurized at higher temperatures (e.g., ~450 and 550°C) in ppm-level H2S experienced significant sulfur loss as confirmed by EDS, which was accompanied by the formation of metal alloys such as Cu3Sn as identified by XRD. On the other hand, samples sulfurized at lower temperatures of ~350°C and even 125°C revealed the formation of CZTS phase as confirmed by XRD, Raman micro-spectroscopy, and sheet resistance measurement. Moreover, local EDS analysis indicates that CZTS films prepared at those low temperatures have near-stoichiometric composition and are sometimes accompanied by the formation of Cu2−xS phase(s). In addition, stoichiometric and Cu-rich precursor solutions tend to yield CZTS samples with better crystallinity and superior optical properties compared with the Cu-deficient solution. These results are discussed from thermodynamics perspective and the directions for future research for safer and more economical processing of CZTS solar cells are pointed out.

Developments in Co(Ni-P) Hybrid Electro-Electroless Deposited (HEED) Alloys and Composites

Hybrid electro-electroless deposition (HEED) is a process defined as the electrochemical reduction of separate and distinct metals or alloys by independent electrochemical processes within a single electrolyte. The present Co/(Ni-P) system is composed of two phases, electroplating and electroless deposition, which each target a different metal ion within the electrolyte. Electroplating produces majority Co films, over 60 % atomically, with the concentration of Ni-P depending on the electrolyte composition and deposition conditions. The electroless deposition phase, carried out within the same electrolyte, produces nearly pure Ni-P deposits, estimated at <2 % Co. The low Co content within electrolessly deposited films is due to the acidity of the electrolyte which prevents the co-deposition of Co. A combination of electrolyte factors, including metal ion ratio, temperature, acidity, and applied potential, control the composition purity of HEED films by controlling the rate of ongoing electroless deposition.

Template-Directed Electrodeposition of Iron-Palladium Nanowires and Their Electrical Transport and Sensing Properties

Template-directed electrodeposition was utilized to fabricate FexPd1-x nanowires where the dimension was controlled by template pore size (i.e., 30 and 200 nm) whereas the composition was tuned by varying the Fe+2/Pd+2 metal ion ratio in ammonium chloride baths at fixed deposition current density of 5 mA cm−2. A wide range of composition (i.e., Pd-rich, near equiatomic, and Fe-rich) were successfully fabricated and their magnetic properties were examined. Additionally, single nanowire was also integrated on to microfabricated gold electrodes by magnetic alignment, followed by post-annealing in a reducing environment to make good electrical contacts. Assembled single nanowire was utilized to determine their electrical transport properties including temperature-dependent resistance (TCR) and magnetoresistance (MR). Additionally, the feasibility of FexPd1-x nanowire based hydrogen sensor was examined at room temperature.

Phytofabrication, characterisation and antimicrobial studies of gold nanoparticles using Cannabis sativa (Bhang), leaf extract

Phytofabrication of gold nanoparticles by plant extract of cannabis sativa is at present under exploitation for the reason to develop environmentally benign nanoparticles synthesis to avoid adverse effects in biomedical applications. Aqueous solution of HAuCl4 4H2O was taken to react with different concentration of ethanolic leaf extract of the plant. A fixed ratio of plant extract and metal ion was mixed which in turn showed the change in colour of the solution leading to the inference that nanoparticles are formed. The characterisation of nanoparticles was done by UV-VIS Spectrophotometer, FTIR, and TEM. The particles synthesised were of the size ranging from 20-100 nm. The solution showed a peak at 560 nm on UV-VIS spectrum corresponding to the surface Plasmon resonance of gold nanoparticles. The shape of the nanoparticles was spherical according to transmission electron microscopy. In these studies, the antimicrobial studies of the AuNPS were exploited against different micro-organisms. The results of UV-VIS, FT-IR and TEM confirm that the leaves extract of Cannabis sativa can be used to produce gold nanoparticles with significant amount of antimicrobial activity.

Phytofabrication, characterisation and antimicrobial studies of gold nanoparticles using Cannabis sativa (Bhang), leaf extract

Phytofabrication of gold nanoparticles by plant extract of cannabis sativa is at present under exploitation for the reason to develop environmentally benign nanoparticles synthesis to avoid adverse effects in biomedical applications. Aqueous solution of HAuCl4 4H2O was taken to react with different concentration of ethanolic leaf extract of the plant. A fixed ratio of plant extract and metal ion was mixed which in turn showed the change in colour of the solution leading to the inference that nanoparticles are formed. The characterisation of nanoparticles was done by UV-VIS Spectrophotometer, FTIR, and TEM. The particles synthesised were of the size ranging from 20-100 nm. The solution showed a peak at 560 nm on UV-VIS spectrum corresponding to the surface Plasmon resonance of gold nanoparticles. The shape of the nanoparticles was spherical according to transmission electron microscopy. In these studies, the antimicrobial studies of the AuNPS were exploited against different micro-organisms. The results of UV-VIS, FT-IR and TEM confirm that the leaves extract of Cannabis sativa can be used to produce gold nanoparticles with significant amount of antimicrobial activity.

Bimetallic metal–organic framework derived porous carbon nanostructures for high performance membrane capacitive desalination

Porous carbons derived from bimetallic metal–organic frameworks exhibit tunable properties by controlling the ratio of metal ions (Zn and Co) in the precursors. With the optimal ratio of Zn/Co = 3 in the precursors, the porous carbons possess a superior electrosorption capacity of 45.6 mg g−1.