Multi-element trace determinations in pure alkaline earth fluoride powders by high-resolution ICP-MS using wet-chemical sample preparation and laser ablation

Four alternative analytical procedures for the determination of ten important trace impurities (Mg, Cr, Fe, Cu, Zn, Sr, Zr, Cd, Ba, and Pb) in pure alkaline earth fluoride powders were applied using high-resolution inductively coupled plasma mass spectrometry (ICP-MS). Two procedures are based on a wet-chemical microwave digestion with boric acid and quantification by the standard addition technique and isotope dilution mass spectrometry (IDMS), respectively. In addition, analyses are also performed by laser ablation as a direct solid sampling technique applying matrix-matched external calibration as well as isotope dilution of the powdered sample. For most elements good agreement between the different methods is found. Detection limits for laser ablation vary between 0.05 ng g^–1 for Zr and 20 ng g^–1 for Mg. They are about one to two orders of magnitude lower than those of the wet-chemical procedures, which is mainly due to the high dilution factor during the sample preparation step. Advantages and restrictions of the different analytical procedures are discussed with respect to their routine applicability. Due to its relatively high accuracy, low detection limits, and time-efficiency LA-ICP-IDMS is the preferred choice if no standard reference materials are available.     

Development of a species-specific isotope dilution GC-ICP-MS method for the determination of thiophene derivates in petroleum products

A species-specific isotope dilution technique for accurate determination of sulfur species in low- and high-boiling petroleum products was developed by coupling capillary gas chromatography with quadrupole ICP-MS (GC-ICP-IDMS). For the isotope dilution step ³⁴S-labeled thiophene, dibenzothiophene, and mixed dibenzothiophene/4-methyldibenzothiophene spike compounds were synthesized on the milligram scale from elemental ³⁴S-enriched sulfur. Thiophene was determined in gasoline, ‘sulfur-free’ gasoline, and naphtha. By analyzing reference material NIST SRM 2296, the accuracy of species-specific GC-ICP-IDMS was demonstrated by an excellent agreement with the certified value. The detection limit is always limited by the background noise of the isotope chromatograms and was determined for thiophene to be 7 pg absolute, which corresponds to 7 ng sulfur/g sample under the experimental conditions used. Dibenzothiophene and 4-methyldibenzothiophene were determined in different high-boiling petroleum products like gas oil, diesel fuel, and heating oil. In this case a large concentration range from about < 0.04 to more than 2,000 μg g⁻¹ was covered for both sulfur species. By parallel GC-ICP-MS and GC-EI-MS experiments (EI-MS electron impact ionization mass spectrometry) the substantial influence of co-eluting hydrocarbons on the ICP-MS sulfur signal was demonstrated, which can significantly affect results obtained by external calibration but not those by the isotope dilution technique.     

Spectral characterization and antibacterial effect of 2-methyl-6-(5-H-Me-Cl-NO <Subscript>2</Subscript>-1<Emphasis Type="Italic">H</Emphasis>-benzimidazol-2-yl)-phenols and some transition metal complexes

2-Methyl-6-(5-H-methyl-chloro-nitro-1H-benzimidazol-2-yl)-phenols( HL _x :x= 1-4)ligands and HL₁ complexes with Fe(NO₃)₃, Cu(NO₃)₂, AgNO₃, Zn(NO₃)₂ have been synthesized and characterized. The structures of the compounds were confirmed on the basis of elemental analysis, molar conductivity, magnetic moment, FT-IR, ¹H-and ¹³C-NMR. Antibacterial activity of the free ligands, their hydrochloride salts and the complexes were evaluated using the disk diffusion method in dimethyl sulfoxide as well as the minimum inhibitory concentration dilution method, against nine bacteria. While HL₁ ligand has not any activity, it’s Ag(I) complex show antibacterial effect toward almost to all the bacteria. Zn(II) complex has antibacterial effect on especially K. pneumoniae, S. epidermidis and S. aureus bacteria.     

Comparison of heavy metal analyses in hydrofluoric acid used in microelectronic industry by ICP-MS and thermal ionization isotope dilution mass spectrometry

An isotope dilution mass spectrometric (IDMS) method with the thermal ionization (TI) technique has been developed for the determination of trace impurities of Cr, Fe, Ni, Cu, Zn, Ag, Cd, Tl, Pb, Th, and U in high-purity HF (50% by weight) used in the semiconductor industry. The evaporation step of the HF solution was carried out in an apparatus which did not significantly contribute to contaminations of the heavy metals to be analysed. This apparatus allowed fast evaporation of the HF solution of up to 200 ml/h and therefore also a fast trace heavy metal/matrix separation was carried out. The evaporation step was also used in connection with inductively coupled plasma mass spectrometry (ICP-MS) when applying the isotope dilution technique and an external calibration for quantification, respectively. The detection limits for TI-IDMS were (in pg/g): Cr=30, Fe=400, Ni=70, Cu=20, Zn=1100, Ag=70, Cd=10, Tl=1, Pb=16, Th=3, and U=1. With ICP-MS in combination with the evaporation step, detection limits of less than 50 pg/g have been achieved for Cr, Ni, and Zn and of <5 pg/g for the other elements except Fe, which could not be determined in concentrations less than 100 ng/g. On the other hand, the detection limits were much higher when the HF matrix was not removed before measuring by ICP-MS. A comparison of the different ICP-MS methods (isotope dilution technique and external calibration for both HF evaporated samples and those with HF matrix) with the results of TI-IDMS has been carried out. An excellent agreement was achieved between the results of TI-IDMS and the two ICP-MS methods using the HF evaporation step, whereas the ICP-MS techniques without HF evaporation essentially deviated from these results. Fe was the only trace element of all investigated heavy metals which could only be analysed by TI-IDMS in high purity HF in a concentration of about 3 ng/g. Although ICP-MS with isotope dilution and external calibration resulted in comparable analytical data, the ICP-IDMS method has some practical advantages such as time-saving and more reliable results.     

Thiol-functionalized Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/SiO<Subscript>2</Subscript> microspheres with superparamagnetism and their adsorption properties for Au(III) ion separation

Thiol-functionalized Fe₃O₄/SiO₂ microspheres (Fe₃O₄/SiO₂-SH) with high saturation magnetization (69.3 emu g^–1), superparamagnetism, and good dispersibility have been prepared by an ethylene glycol reduction method in combination with a modified Stöber method. The as-prepared composite magnetic spheres are characterized with fourier transform infrared spectroscopy (FT-IR), zeta potential, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and superconducting quantum interference magnetometer, and tested in separation of Au(III) ions from aqueous solutions. The data for Au(III) adsorption on Fe₃O₄/SiO₂-SH are analyzed with the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models, and the pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetics models. The adsorption behaviors of Au(III) on Fe₃O₄/SiO₂-SH follow the Langmuir isotherm model, and the adsorption process conforms to the pseudo-second-order kinetic model. The maximum adsorption capacity of Au(III) on Fe₃O₄/SiO₂-SH is 43.7 mg g^–1. Acetate anions play an important role yet Cu(II) ions have little interference in the adsorption of Au(III) on the adsorbent. A satisfactory recovery percentage of 89.5% is acquired by using an eluent with 1 M thiourea and 5% HCl, although thiols have a high affinity to Au(III) ions based on the hard-soft acid-base (HSAB) theory by Pearson.     

Carbon paste electrode modified with Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles and BMI.PF<Subscript>6</Subscript> ionic liquid for determination of estrone by square-wave voltammetry

A carbon paste electrode (CPE) modified with Fe₃O₄ nanoparticles (Fe₃O₄ NP) and the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (IL BMI.PF₆) was employed for the electroanalytical determination of estrone (E1) by square-wave voltammetry (SWV). At the modified electrode, cyclic voltammograms of E1 in B–R buffer (pH 12.0) showed an adsorption-controlled irreversible oxidation peak at around +0.365 V. The anodic current increased by a factor of five times and the peak potential shifted 65 mV to less positive values compared with the unmodified CPE. Under optimized conditions, the calibration curve obtained showed two linear ranges: from 4.0 to 9.0 μmol L^?1 and from 9.0 to 100.0 μmol L^?1. The limits of detection (LOD) and quantification (LOQ) attained were 0.47 and 4.0 μmol L^?1, respectively. The proposed modified electrode was applied to the determination of E1 in pork meat samples. Data provided by the proposed modified electrode were compared with data obtained by UV–vis spectroscopy. The outstanding performance of the electrochemical device indicates that Fe₃O₄ NP and the IL BMI.PF₆ are promising materials for the preparation of chemically modified electrodes for the determination of E1.     

Determination of Cd,Hg, Pb and Se in sediments slurries by isotopic dilution calibration ICP-MS after chemical vapor generation using an on-line system or retention in an electrothermal vaporizer treated with iridium

A method for the determination of Cd, Hg, Pb and Se in sediments reference materials by slurry sampling chemical vapor generation (CVG) using isotopic dilution (ID) calibration and detection by inductively coupled plasma mass spectrometry (ICP-MS) is proposed. Two different systems were used for the investigation: an on-line flow injection system (FI-CVG-ICP-MS) and an off-line system with in situ trapping electrothermal vaporization (CVG-ETV-ICP-MS). About 100 mg of the reference material, ground to a particle size ≤50 μm, was mixed with acid solutions (aqua regia, HF and HCl) in an ultrasonic bath. The enriched isotopes ¹¹¹Cd, ¹⁹⁸Hg, ²⁰⁶Pb and ⁷⁷Se were then added to the slurry in an adequate amount in order to produce an altered isotopic ratio close to 1. For the on-line system, a standing time for the slurry of 12 h before measurement was required, while for the batch system, no standing time is needed to obtain accurate results. The conditions for the formation of the analyte vapor were optimized for the evaluated systems. The following altered isotope ratios were measured: ¹¹¹Cd/¹¹⁴Cd, ¹⁹⁸Hg/¹⁹⁹Hg, ²⁰⁶Pb/²⁰⁸Pb e ⁷⁷Se/⁸²Se. The obtained detection limits in the on-line system, in μg g⁻¹, were: Cd: 0.15; Hg: 0.09; Pb: 6.0 and Se: 0.03. Similar detection limits were obtained with the system that uses the ETV: 0.21 for Hg, 6.0 for Pb and 0.06 μg g⁻¹ for Se. No signal for Cd was obtained in this system. One estuarine, two marine and two river certified sediments were analyzed to check the accuracy. The obtained values by both systems were generally in agreement with the certified concentrations, according to the t-test for a confidence level of 95%, demonstrating that isotope equilibration was attained in the slurries submitted to a chemical vapor generation procedure and detection by ICP-MS. The relative standard deviations were lower than 10%, adequate for slurry analysis. The almost quantitative analytes extractions to the aqueous phase of the slurry must favor equilibration of the added enriched isotope with the isotope in the sample, allowing the use of isotopic dilution calibration for slurry analysis.     

Comparison between hydride generation and nebulization for sample introduction in the determination of lead in plants and water samples by inductively coupled plasma mass spectrometry,using external calibration and isotope dilution

Four inductively coupled plasma mass spectrometric methods: nebulization sample introduction with external calibration; hydride generation with external calibration; isotope dilution with nebulization; and isotope dilution with hydride generation, have been tested and compared. Multimode Sample Introduction System (MSIS™) was employed in either nebulization or hydride generation mode. Best limits of detection (below 0.1 μg L^− 1) and accuracy were obtained for isotope dilution techniques in hydride generation and sample nebulization mode. A mixture of HNO₃ and H₂O₂ served both for microwave-assisted digestion as well as a medium for subsequent plumbane generation. Optimal reagent concentrations for hydride generation stage were 0.1 mol L^− 1 HNO₃, 0.28 mol L^− 1 H₂O₂ and 1.5% m/v NaBH₄. Critical effects of acidity, blanks and concomitants have been discussed. Analytical methods were validated by use of plant and water certified reference materials and spiked high-salt solutions (seawater and 20% m/v NaCl) at lead levels in nanograms per gram to micrograms per gram range.     

Supramolecular microrods can be prepared by mixing aqueous Ru(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>Cl<Subscript>3</Subscript> and K<Subscript>3</Subscript>Fe(CN)<Subscript>6</Subscript> solutions at room temperature

This paper describes the ionic self-assembly method to fabricate supramolecular one-dimensional microrods in solution. Such microrods were formed in a one-step process through the mixing aqueous Ru(NH₃)₆Cl₃ and K₃Fe(CN)₃ solutions at room temperature. Chemical composition of the resulting structures, which are composed of from Fe(CN)₆⁴⁻ and Ru(NH₃)₆³⁺, was determined by energy-dispersed spectroscopy. The data show that the formation of microrods depends on the molar ratio and concentration of the reactants.     

Uncertainty of determination of palladium in road dust sample by inductively coupled plasma mass spectrometry

The determination of palladium in a road dust sample taken close to the highway (w _Pd=450 ng g⁻¹) was carried out by the ICP-MS method after sample decomposition by aqua-regia. Analyses were evaluated by two methods: external calibration accompanied with mathematical correction of spectral interferences (EC) and isotope dilution measurement after separation of Pd by extraction to dibutyl sulfide solution (ID). In both cases, the uncertainties and accuracy of results were investigated. Although in the case of ideally homogeneous sample the repeatability of EC results (11 ng g⁻¹ Pd) was somewhat lower than those of ID results (16 ng g⁻¹ Pd), the uncertainties of results of both techniques were almost the same and they reached the level of 19 ng g⁻¹ Pd. The main uncertainty source of the EC method is represented by the correction of spectral interferences. In case of real non-homogeneous sample, the main uncertainty component represents the soil sampling. The uncertainty of results (approx. 75 ng g⁻¹ Pd) only slightly exceeded the repeatability (approx. 70 ng g⁻¹ Pd). The accuracy of results was proven by analyses of CRM TDB–1 Diabas Rock (in case of ID) and by the standard addition method (in case of EC).     

Quantification of Imidacloprid in Honeybees: Development of a Chemiluminescent ELISA

A Chemiluminescent Enzyme-Linked Immuno-Sorbent Assay (CL-ELISA) for determination and quantification of the fungicide imidacloprid in honeybees was developed in an indirect competitive format. The assay was optimized by determining: the optimal coating conjugate concentration and anti-imidacloprid antiserum dilution, the effect of the incubation time on the competitive step, and the tolerance to organic solvents. The IC₅₀ and the limit of detection (LOD) values were 14.8 ng mL^?1 and 0.11 ng mL^?1, respectively, similar to those of colorimetric ELISA with a calibration range of 0.1–2600 ng mL^?1. Cross reactivity of some related compounds such as three imidacloprid metabolites, 6-chloro nicotinic acid, 5-hydroxy-imidacloprid, and imidacloprid olefin, and one other chloronicotinoid insecticide, acetamiprid, were tested. The assay was then applied to honeybee extracts obtained by using the liquid-liquid extraction. The calibration curves in honeybee extracts from the liquid-liquid procedure gave an IC₅₀ of 23.7 ng mL^?1 and a LOD 1.6 ng mL^?1. The average recovery value from honeybee extracts spiked with 100 and 1000 ng mL^?1 of imidacloprid were 73% and 76%, respectively. Finally, the assay was applied to honeybee samples collected during monitoring activities in Italy; it was found that only five of the 27 samples were positives, with low concentrations of imidacloprid ranging between 1.2 and 15.4 ng g^?1.     

The influence of structural factors on the gas-sensitive properties of Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>-SnO<Subscript>2</Subscript>

The influence of the dispersity and structural and phase state of oxide materials based on Fe₂O₃ and SnO₂ on the gas-sensitive properties of these materials used as sensitive layers in chemical sensors was considered. It was found that high-dispersity Fe₂O₃-SnO₂ (Fe: Sn = 9: 1) ceramic layers possessed high sensitivity to ethanol vapor in both dry and humid atmosphere and low sensitivity to CO and CH₄. The maximum response to ethanol vapor in humid atmosphere was characteristic of layers with structures of substitution-interstitial solid solutions of Sn⁴⁺ in α-Fe₂O₃.     

Green fabrication of sandwich-like and dodecahedral C@Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@C as high-performance anode for lithium-ion batteries

Sandwich-structured C@Fe₃O₄@C hybrids with Fe₃O₄ nanoparticles sandwiched between two conductive carbon layers have attracted more and more attention owing to enhanced synergistic effects for lithium-ion storage. In this work, an environment-friendly procedure is developed for the fabrication of sandwich-like C@Fe₃O₄@C dodecahedrons. Zeolitic imidazolate framework (ZIF-8)-derived carbon dodecahedrons (ZIF-C) are used as the carbon matrix, on which iron precursors are homogeneously grown with the assistance of a polyelectrolyte layer. The subsequent polydopamine (PDA) coating and calcination give rise to the formation of sandwiched ZIF-C@Fe₃O₄@C. When being evaluated as the anode material for lithium-ion batteries, the obtained hybrid manifests a high reversible capacity (1194 mAh g^?1 at 0.05 A g^?1), good high-rate behavior (796 mAh g^?1 at 10 A g^?1), and negligible capacity loss after 120 cycles.     

Application of stable isotopes in environmental tracer studies – Measurement of monomethylmercury (CH3Hg+) by isotope dilution ICP-MS and detection of species transformation

The monovalent cation monomethylmercury (CH₃Hg⁺) was determined in certified reference materials by isotope dilution GC/ICP-MS and good agreement between measured and certified values has been found. The use of enriched stable isotopes with subsequent detection by ICP-MS is a powerful tracer technique to study dynamic environmental processes. For the first time, it was possible to monitor opposite processes like Hg²⁺ methylation and CH₃Hg⁺ demethylation at ambient tracer levels simultaneously in the same sample. A scheme for calculating the formation of new species from stable tracers used in environmental studies is presented. The sensitivity of stable tracer methods is superior to traditional tracer or radiotracer techniques. In case of mercury methylation, where the generation of a new compound is monitored, the limit of detection depends only on the precision of the isotope ratio measurements and the concentration of the ambient CH₃Hg⁺ already present in the sample, not on the absolute detection limit of the GC/ICP-MS technique used for analyzing CH₃Hg⁺. A 0.25% change in concentration of CH₃Hg⁺ is detectable. In the case of CH₃Hg⁺ demethylation, where the decrease of the added tracer is monitored, the detection limit again depends on the precision of the isotope ratio measurement and the ambient CH₃Hg⁺ concentration but additionally on the amount of the added tracer as well. A decrease in the CH₃Hg⁺ level of 2% of the added tracer is detectable. The validity of the calculation scheme was tested and no difference was found between individually measured isotope concentrations and calculated concentrations from solutions with multiple stable tracers.     

Sb<Subscript>2</Subscript>S<Subscript>3</Subscript>-SiO<Subscript>2</Subscript> nanocomposite layers synthesized using the layer-by-layer technique

Possibility of layer-by-layer synthesis by colloidal layering of Sb₂S₃-SiO₂ nanocomposite layers from colloid solutions of {[H _x Sb₂S₅] ^m ?}mNa⁺ and SiO₂ was studied. The composition of the layers synthesized was examined by Raman spectroscopy, transmission spectroscopy in the UV and visible spectral ranges, energy-dispersion micro analysis, and scanning electron microscopy.     

Constant current anodic stripping chronopotentiometric determination of uranium in uranium mineral ores via accumulation of K<Subscript>2</Subscript>UO<Subscript>2</Subscript>[Fe(CN)<Subscript>6</Subscript>] on the palladium plated aluminum electrode

In the present work the uranyl hexacyanoferrate (K₂UO₂[Fe(CN)₆]) is deposited on the palladized aluminum (Pd-Al) electrode from a \textUO₂^{2 +} + \textFe( \textCN )₆ ^{- 3} {\text{UO}}_{2}^{2 + } + {\text{Fe}}\left( {\text{CN}} \right)_{6}^{ - 3} solution. Then the anodic stripping chronopotentiometry (ASCP) was used to strip the K₂UO₂[Fe(CN)₆] from the Pd-Al surface. The operational conditions including: pH, K₃Fe(CN)₆ concentration, deposition potential, deposition time and stripping current were optimized. The ASCP calibration graph was linear in concentration range 10–460 μM. of \textUO₂^{2 +} {\text{UO}}_{2}^{2 + } and the detection limit was 8.5 μM. The interference of some concomitant ions during the deposition process of K₂UO₂[Fe(CN)₆] was studied. The proposed method was successfully applied for analysis of some uranium mineral ores.     

Photo-fenton refreshable Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@HCS adsorbent for the elimination of tetracycline hydrochloride

A yolk–shell-structured sphere composed of a superparamagnetic Fe₃O₄ core and a carbon shell (Fe₃O₄@HCS) was etched from Fe₃O₄@SiO₂@carbon by NaOH, which was synthesized through the layer-by-layer coating of Fe₃O₄. This yolk–shell composite has a shell thickness of ca. 27 nm and a high specific surface area of 213.2 m² g^?1. Its performance for the magnetic removal of tetracycline hydrochloride from water was systematically examined. A high equilibrium adsorption capacity of ca. 49.0 mg g^?1 was determined. Moreover, the adsorbent can be regenerated within 10 min through a photo-Fenton reaction. A stable adsorption capacity of 44.3 mg g^?1 with a fluctuation <10% is preserved after 5 consecutive adsorption–degradation cycles, demonstrating its promising application potential in the decontamination of sewage water polluted by antibiotics.     

External calibration strategy for trace element quantification in botanical samples by LA-ICP-MS using filter paper

The use of reference solutions dispersed on filter paper discs is proposed for the first time as an external calibration strategy for matrix matching and determination of As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, V and Zn in plants by laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS). The procedure is based on the use of filter paper discs as support for aqueous reference solutions, which are further evaporated, resulting in solid standards with concentrations up to 250 μg g⁻¹ of each element. The use of filter paper for calibration is proposed as matrix matched standards due to the similarities of this material with botanical samples, regarding to carbon concentration and its distribution through both matrices. These characteristics allowed the use of ¹³C as internal standard (IS) during the analysis by LA-ICP-MS. In this way, parameters as analyte signal normalization with ¹³C, carrier gas flow rate, laser energy, spot size, and calibration range were monitored. The calibration procedure using solution deposition on filter paper discs resulted in precision improvement when ¹³C was used as IS. The method precision was calculated by the analysis of a certified reference material (CRM) of botanical matrix, considering the RSD obtained for 5 line scans and was lower than 20%. Accuracy of LA-ICP-MS determinations were evaluated by analysis of four CRM pellets of botanical composition, as well as by comparison with results obtained by ICP-MS using solution nebulization after microwave assisted digestion. Plant samples of unknown elemental composition were analyzed by the proposed LA method and good agreement were obtained with results of solution analysis. Limits of detection (LOD) established for LA-ICP-MS were obtained by the ablation of 10 lines on the filter paper disc containing 40 μL of 5% HNO₃ (v v⁻¹) as calibration blank. Values ranged from 0.05 to 0.81  μg g⁻¹. Overall, the use of filter paper as support for dried aqueous standards showed to be a useful strategy for calibration and plant analysis by LA-ICP-MS.     

Determination of uranium in marine sediment pore waters by isotope dilution inductively coupled plasma mass spectrometry

Inductively coupled plasma mass spectrometry (ICP-MS) was used in an isotope dilution mode to assay small-volume (0.25 ml) sediment pore waters for their uranium contents, using ²³⁶U as the spike. The only pretreatment required was a simple dilution by a factor of 20, which gave sufficient volume for three replicate analyses per sample. Rapid and accurate results were obtained for a variety of samples and standards, ranging in concentration from 0.05 to 10 ng U ml^?1. A suite of 30 samples can be analysed in less than 6 h by this method. The relative standard deviation was better than 1.9%, with a detection limit, based on 3σ background, of 2 pg U ml^?1 in solution (40 pg ml^?1 in samples). Sea water is a difficult matrix for ICP-MS and thus the method is generally suitable for uranium determinations in many other sample solutions.     

Porous,hollow Li<Subscript>1.2</Subscript>Mn<Subscript>0.53</Subscript>Ni<Subscript>0.13</Subscript>Co<Subscript>0.13</Subscript>O<Subscript>2</Subscript> microspheres as a positive electrode material for Li-ion batteries

A porous, hollow, microspherical composite of Li₂MnO₃ and LiMn_1/3Co_1/3Ni_1/3O₂ (composition: Li_1.2Mn_0.53Ni_0.13Co_0.13O₂) was prepared using hollow MnO₂ as the sacrificial template. The resulting composite was found to be mesoporous; its pores were about 20 nm in diameter. It also delivered a reversible discharge capacity value of 220 mAh g^?1 at a specific current of 25 mA g^?1 with excellent cycling stability and a high rate capability. A discharge capacity of 100 mAh g^?1 was obtained for this composite at a specific current of 1000 mA g^?1. The high rate capability of this hollow microspherical composite can be attributed to its porous nature.

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