Interlayer NO3 Research Articles

Yttrium doping stabilizes the structure of Ni3(NO3)2(OH)4 cathodes for application in advanced Ni-Zn batteries.

Ni3(NO3)2(OH)4 has a high theoretical specific capacitance, low cost, and environmental friendliness, making it a promising electrode material. Specifically, Ni3(NO3)2(OH)4 electrodes have a larger layer spacing (c = 6.898 Å) than Ni(OH)2 electrodes since NO3- has a much larger ionic radius than OH-. The larger layer spacing stores more electrolyte ions, significantly improving the electrochemical activity of the electrodes. Additionally, the interlayer NO3- can enhance the structural stability of Ni3(NO3)2(OH)4. However, since Ni3(NO3)2(OH)4 has a higher molar mass than Ni(OH)2, it has a lower theoretical specific capacity. Consequently, Ni3(NO3)2(OH)4 has not been used in zinc-based alkaline batteries. Studies showed that doping could enhance the electrochemical performance of electrode materials. Therefore, this study used a simple solvothermal reaction to synthesize yttrium-doped Ni3(NO3)2(OH)4 (Y-Ni3(NO3)2(OH)4), assembling a Y-Ni3(NO3)2(OH)4//Zn battery for electrochemical testing. Y-Ni3(NO3)2(OH)4 served as the cathode in the battery. The analysis of Y-Ni3(NO3)2(OH)4 showed that yttrium (Y) doping increased the specific surface area and pore size of Ni3(NO3)2(OH)4 significantly. The increased specific surface area improved the active material utilization, and the abundant mesopores facilitated OH- transport, substantially enhancing the battery's specific capacity and energy density. Ultimately, the specific discharge capacity of the advanced Y-Ni3(NO3)2(OH)4//Zn battery reached 177.97 mA h g-1 at a current density of 4 A g-1, nearly doubling the capacity of the earlier Ni3(NO3)2(OH)4//Zn battery (103.59 mA h g-1).

Lithium storage performance of α-Ni(OH)2 regulated by partial interlayer anion exchange

Hierarchical flower-like α-Ni(OH)2 with interlayer NO3− is prepared via a homogeneous precipitation method. To optimize the lithium storage performance of the α-Ni(OH)2 sample, the interlayer NO3− is partially exchanged by Cl−, SO42−, CO32−, PO43−, and OH−, respectively. The results demonstrate that the α-Ni(OH)2 samples exchanged by SO42−, CO32−, Cl−, and OH− exhibit improved rate capability and enhanced pseudocapacitive behavior. The α-Ni(OH)2 with interlayer NO3− and the ones exchanged by SO42− and Cl− suffer from poor cyclic stability after 50 cycles at a current density of 1.0 A g−1. In contrast, the α-Ni(OH)2 samples exchanged by CO32−, PO43−, and OH− exhibit much-enhanced cyclic stability compared to the α-Ni(OH)2 with interlayer NO3−. The α-Ni(OH)2 with interlayer NO3− and the ones exchanged by SO42− and Cl− deliver capacities of 265, 197, and 341 mA h g−1, respectively, after 500 cycles at a current density of 1.0 A g−1, while the α-Ni(OH)2 samples exchanged by CO32−, PO43−, and OH− maintain reversible capacities of 980, 1172, and 879 mA h g−1, respectively, after 500 cycles at a current density of 1.0 A g−1. This work provides a new avenue for the rational design and performance optimization of α-Ni(OH)2 as an anode material for lithium-ion batteries.

A novel composite of layered double hydroxide/geopolymer for co-immobilization of Cs+ and SeO42− from aqueous solution

Geopolymers are always considered as promising materials for the treatment of radioactive wastes. In order to extend the application of geopolymer to the immobilization of anionic species, a novel composite of layered double hydroxide/geopolymer (LDH/GEO) was synthesized and applied for cosorption of Cs+ and SeO42−. The ability of LDH/GEO to sorb Cs+ was maintained as that of pure GEO, even though the surface of geopolymer was homogeneously covered by the LDH platelets. The sorption of Cs+ onto LDH/GEO composite occurred via ion exchange, which was controlled by particle diffusion. It is different with Cs+ sorption onto pure GEO governed by film diffusion. Therefore, “Pocket diffusion” was proposed for the particle diffusion as the case of LDH/GEO because this kind of diffusion would be restricted in a certain distance around the ring entrance gate due to the amorphous essence of GEO. For SeO42− sorption by LDH/GEO, ion-exchange with the interlayer NO3− and surface sorption could be the main mechanisms. Importantly, the sorption speed of SeO42− achieved by LDH/GEO composite was much faster than that by pure LDH. In the binary system (Cs++ SeO42−), the sorption of Cs+ was slightly suppressed compared to the single system, which might be due to the formation of ion-pair complex of [CsSeO4]−. However, it did not have negative effect on the SeO42− sorption. In the presence of other cations or anions, the cosorption performances of Cs+ and SeO42− were satisfactorily obtained. Furthermore, the Cs+ and SeO42- sorption densities were superior to the previously reported values. The combined MgAl-LDH/geopolymer composite could be a promising material for the immobilization of Cs+ and SeO42−, and this work would provide guidance for the development of geopolymer-based materials for environmental applications.

The Effects of Halogen Exchange on the Structural Features, Thermal Behavior and Photoluminescence of Y/Eu Layered Rare-Earth Hydroxide (LRH) Nanosheets

Solid-solution nanosheets (down to ~5 nm thick, in the form of flower like assemblies) of the (Y0.95Eu0.05)2NO3∙nH2O were directly synthesized via chemical precipitation at the freezing temperature of ~4°C. In situ exchange of the interlayer NO3- with halogen anions produced a series of halogen derivatives (Y0.95Eu0.05)2X∙nH2O (X= F-, Cl-, Br- and I-) of the same layered structure and two-dimensional crystallite morphology. The basal spacing of the derivatives was discussed from the geometric size/spatial orientation of the anions and also from anion-host interaction via electrostatic attraction and hydrogen bonding. The thermal behavior and photoluminescence spectroscopies were found to be strongly related to the anion-host interactions.

Sulfate Exchange of the Nitrate-Type Layered Hydroxide Nanosheets of Ln2(OH)5NO3·nH2O for Better Dispersed and Multi-color Luminescent Ln2O3 Nanophosphors (Ln = Y0.98RE0.02, RE = Pr, Sm, Eu, Tb, Dy, Ho, Er, and Tm).

Through restricting thickness growth by performing coprecipitation at the freezing temperature of ~4 °C, solid-solution nanosheets (up to 5-nm thick) of the Ln2(OH)5NO3·nH2O layered hydroxide (Ln = Y0.98RE0.02; RE = Pr, Sm, Eu, Tb, Dy, Ho, Er, and Tm, respectively) were directly synthesized without performing conventional exfoliation. In situ exchange of the interlayer NO3− with SO42− produced a sulfate derivative [Ln2(OH)5(SO4)0.5·nH2O] of the same layered structure and two-dimensional crystallite morphology but substantially contracted d002 basal spacing (from ~0.886 to 0.841 nm). The sulfate derivative was systematically compared against its nitrate parent in terms of crystal structure and phase/morphology evolution upon heating. It is shown that the interlayer SO42−, owing to its bonding with the hydroxide main layer, significantly raises the decomposition temperature from ~600 to 1000 °C to yield remarkably better dispersed oxide nanopowders via a monoclinic Ln2O2SO4 intermediate. The resultant (Y0.98RE0.02)2O3 nanophosphors were studied for their photoluminescence to show that the emission color, depending on RE3+, spans a wide range in the Commission Internationale de l’Eclairage (CIE) chromaticity diagram, from blue to deep red via green, yellow, orange, and orange red.

Structural and textural characteristics of systems based on layered Mg-Al hydroxides

Hydrotalcite-type layered Mg-Al hydroxides with Mg/Al ≥ 2 and related oxide systems have been synthesized and characterized. During the synthesis of the Mg-Al hydroxides with Mg/Al = 2 and 3, the interplanar spacings decrease because of the replacement of the interlayer NO 3 − anion by the CO 3 2− anion. Morphologically, the initial materials are aggregates of ∼1-μm oblong planar particles with a layered structure. The transverse dimension of the plates is 50–100 nm, and their thickness is 10–30 nm. As a rule, these planar particles are heavily distorted. Heat treatment of the Mg-Al hydroxides in the temperature range from 450 to 600°C causes the separation of the layered structures into planar domains of epitaxial MgAl2O4/MgO structures, which survive heat treatment at 900°C. During this heat treatment at 900°C, the greater part of the sample breaks down into two-dimensional particles of defective MgO and MgAl2O4 phases whose size is up to 100 nm. The oxide compositions synthesized from the layered Mg-Al hydroxides have a large pore volume and a fairly high specific surface area, which are retained upon heat treatment at 1000–1100°C.

Controlled Synthesis of Layered Rare‐Earth Hydroxide Nanosheets Leading to Highly Transparent (Y0.95Eu0.05)2O3 Ceramics

Chemical precipitation at the freezing temperature of ~4°C has directly yielded layered rare‐earth hydroxide [LRH, Ln2(OH)5NO3·nH2O, Ln = Y0.95Eu0.05] nanosheets (up to 7 nm thick) for the Y/Eu binary system, with the interlayer NO3− exchangeable with SO42−. Calcining the sulfate derivative at 1100°C for 4 h produces well‐dispersed and readily sinterable Ln2O3 red phosphor powders (~14.8 m2/g) that can be densified into highly transparent ceramics via optimized vacuum sintering at the relatively low temperature of 1700°C for 4 h (average grain size ~14 μm; in‐line transmittance ~80% at the 613 nm Eu3+ emission or ~99% of the theoretical transmittance of Y2O3 single crystal). Our systematic studies also found that (1) the extent of SO42− exchange and the interlayer distance of LRH are both affected by the SO42−/Ln3+ molar ratio (R), and an almost complete exchange is achievable at R = 0.25 as expected from the chemical formula (one SO42− replaces two NO3− for charge balance). The optimal R value for sintering, however, was found to be 0.03; (2) The Ln3+ concentration for LRH synthesis substantially affects properties of the resultant oxides, and hard agglomeration has been significantly reduced at the optimized Ln3+ concentration of 0.05–0.075 mol/L; (3) Sulfate exchange significantly alters the thermal decomposition pathway of LRH, and was found essential to produce well‐dispersed and highly sinterable oxide powders; (4) Both the oxide powders and transparent ceramics exhibit the typical red emission of Eu3+ at ~613 nm (the 5D0→7F2 transition) under charge‐transfer (CT) excitation. Red‐shifted CT band center, stronger excitation/emission, and shorter fluorescence lifetime were, however, observed for the transparent ceramics.

Enhanced electrochemical performance of high-density Al-substituted α-nickel hydroxide by a novel anion exchange method using NaCl solution

High-density Al-substituted α-nickel hydroxide with interlayer NO3− for alkaline nickel-based rechargeable batteries has been synthesized using a polyacrylamide (PAM) assisted two-step drying method. In order to improve its electrochemical performance, Al-substituted α-Ni(OH)2 with interlayer NO3− is modified by a simple anion exchange method using NaCl solution. The physical and electrochemical properties of the synthesized material are characterized by means of X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and a charge–discharge test. Compared with NO3− intercalated α-Ni(OH)2 precursor, the resulting Cl− intercalated α-Ni(OH)2 samples possess more excellent electrochemical activities, including higher proton diffuse coefficient, lower electrochemical impedance, higher specific capacity, and better cyclic stability. Especially, it is also found that the introduction of Cl− can greatly accelerate the activation process of α-Ni(OH)2 electrodes.

The Effects of Sulfate Anion Exchange on Structural Feature and Thermal Behavior of Y<sub>2</sub>(OH)<sub>5</sub>NO<sub>3</sub>•<i>n</i>H<sub>2</sub>O Layered Hydroxide Nanosheets

Layered rare-earth hydroxide nanosheets (3-8 nm thick) of Y2(OH)5NO3·nH2O (NO3--LYH) were successfully synthesized in one step via chemical precipitation at ~4 °C and pH ~8, using yttrium nitrate and ammonium hydroxide as reagents. The interlayer NO3- was found to be free ions and can be completely replaced with SO42- to yield Y2(OH)5(SO4)0.5·nH2O (SO42--LYH). Thermal decomposition behavior of the SO42--LYH was studied in detail, and the phase and morphology evolutions upon calcination in the temperature range 500-1100 °C were also investigated. Characterizations via XRD, FE-SEM, TEM, and FT-IR found that anion exchange did not bring about any appreciable change to the 2-dimensional crystallite morphology but the basal spacing of the crystal structure shrank from ~0.884 to 0.840 nm owing to the indirect coordination of SO42- to the Y3+ ions. DTA/TG and XRD analysis found that the NO3--LYH converts to Y2O3 at ~600 °C, but the SO42--LYH decomposes to oxide at a higher temperature of ~1000 °C via monoclinic Y2O2SO4 in the range of 800-900 °C. The resultant Y2O3 particles have an average size of ~60 nm.

Trace analysis of mefenamic acid in human serum and pharmaceutical wastewater samples after pre-concentration with Ni–Al layered double hydroxide nano-particles

In this work, the nickel–aluminum layered double hydroxide (Ni–Al LDH) with nitrate interlayer anion was synthesized and used as a solid phase extraction sorbent for the selective separation and pre-concentration of mefenamic acid prior to quantification by UV detection at λmax=286nm. Extraction procedure is based on the adsorption of mefenamate anions on the Ni–Al(NO3−) LDH and/or their exchange with LDH interlayer NO3− anions. The effects of several parameters such as cations and interlayer anions type in LDH structure, pH, sample flow rate, elution conditions, amount of nano-sorbent and co-existing ions on the extraction were investigated and optimized. Under the optimum conditions, the calibration graph was linear within the range of 2–1000µg/L with a correlation coefficient of 0.9995. The limit of detection and relative standard deviation were 0.6µg/L and 0.84% (30µg/L, n=6), respectively. The presented method was successfully applied to determine of mefenamic acid in human serum and pharmaceutical wastewater samples.

A nano-structured material for reliable speciation of chromium and manganese in drinking waters, surface waters and industrial wastewater effluents

A simple solid phase extraction system based on the applying the nickel–aluminum layered double hydroxide (Ni–Al LDH) as a nano-sorbent was developed for the speciation analysis of chromium and manganese by flame atomic absorption spectrometry (FAAS). The method is based on the fact that Cr(VI) and Mn(VII) oxyanions could be adsorbed on the Ni–Al(NO3−) LDH and/or exchanged with LDH interlayer NO3− ions at pH 6.0, whereas Cr(III) and Mn(II) cations pass through the LDH-packed column without retention. The determinations of total Cr and Mn, and hence indirectly Cr(III) and Mn(II), involve the pre-oxidations of Cr(III) and Mn(II) to Cr(VI) and Mn(VII) with H2O2 and acidic solution of KIO4, respectively. Several important factors affecting the retention efficiency were investigated and optimized. In the optimum experimental conditions, the limits of detection (3Sb/m) for Cr(VI) and Mn(VII) were 0.51 and 0.47ngmL−1, and the relative standard deviations were 2.5 and 3.2% (C=30.0ngmL−1, n=6), respectively. The presented method was validated by the analysis of a certified reference material, and applied to the speciation of Cr and Mn in drinking waters, surface waters and industrial wastewater effluents.

Nickel–aluminum layered double hydroxide as a nanosorbent for selective solid-phase extraction and spectrofluorometric determination of salicylic acid in pharmaceutical and biological samples

The nickel–aluminum layered double hydroxide (Ni–Al LDH) was synthesized by a simple co-precipitation method and used as a solid-phase extraction (SPE) sorbent for separation and pre-concentration of trace levels of salicylic acid (SA) from aqueous solutions. Extraction of analyte is based on the adsorption of salicylate ions on the Ni–Al (NO3−) LDH and/or their exchanging with LDH interlayer NO3− ions. The retained analyte on the LDH was stripped by 3molL−1 NaOH solution and its concentration was subsequently determined spectrofluorometrically at λem=400nm with excitation at λex=270nm. Various parameters affecting the extraction efficiency of SA on the Ni–Al (NO3−) LDH, such as pH, amount of nano-sorbent, sample loading flow rate, elution conditions, sample volume and matrix effects were investigated. In the optimum experimental conditions, the limit of detection (3s) and enrichment factor were 0.12μgL−1 and 40, respectively. The relative standard deviation (RSD) for six replicate determinations of 10μgL−1 SA was 2.3%. The calibration graph using the pre-concentration system was linear in the range of 0.3–45μgL−1 with a correlation coefficient of 0.9985. The optimized method was successfully applied to the determination of SA in blood serum, willow leaf and aspirin tablet.

Synthesis of layered double hydroxides in W/O micro-emulsion: Influence of method of preparation on the physico-chemical and adsorption characteristics

ABSTRACTZn/Al layered double hydroxide was synthesized in micro-emulsion system with the oil phase comprising of cyclohexane + TX100 (surfactant) + n-hexanol (co-surfactant). Aqueous NaOH solution was used as the precipitating agent. The XRD pattern showed Zincite as the primary and hydrotalcite as the secondary phase. The d003 diffraction peak corresponded to interlayer hydroxide ion. There was no interlayer NO3- ion. The synthesized LDH showed much higher BET surface area (116.3 m2/g) than similar LDH synthesized by conventional co-precipitation technique (4.2 m2/g). Well defined flaky nano-crystals having an average dimension of 5-20 nm were observed by HRTEM.

Synthesis and Characterization of Neutral and Cationic Layered Materials Based on Heavier Group 14 Metals: BING-5, -6, -9, -10

ABSTRACTOur research involves the solvothermal synthesis and characterization of new 3D open-framework and low dimensional inorganic materials. We focus on heavier group 14 elements to prepare structures that are analogous to aluminosilicate zeolites, but the main emphasis is to obtain cationic materials, a feat not possible with silicon oxides. We have successfully synthesized a series of novel compounds with Pb as building block: a cationic layered lead fluoride material (BING-5, Pb3F5NO3); a neutral, layered lead phenylphosphonate pyridine (BING-6); and a layered lead metamethylphenyl-phosphonate (BING-9). A molecular solid, tetrafluorodipyridine-germanium (BING-10) was also obtained. These structures are characterized by a variety of solid state techniques, including: powder X-Ray diffraction (PXRD), thermogravimetric analysis (TGA), UV-Vis spectroscopy and NMR. Our BING-5 material can exchange its interlayer NO3- for a variety of other anions. It is also stable to 450°C, which is far superior to organic resins that are still the standard for anion-exchange.

Layered Double Hydroxide as Gene Reservoir

Novel bio-/organic-inorganic hybrid compounds of deoxyribonucleic acid (DNA) and methotrexate (MTX)-layered double hydroxide are prepared by ion-exchange type intercalation reaction. The layered inorganic support. Mg2Al(NO3)-LDH, is at first obtained by coprecipitation in an aqueous solution, and then the interlayer NO3 − anions are replaced by guest molecules such as methotrexate (an anticancer drug) and deoxyribonucleic acid (about 500 ∼ 1000 base pairs), leading to form new bio-/organic-nanohybrids. Upon intercalating guest molecules into hydroxide layers, the basal spacing of LDH increases from 8.5 Å (NO3 −) to 20.8 Å (MTX) and 23.9 Å (DNA), respectively. According to the X-ray diffraction and infrared spectroscopic analyses, it is found that the target molecules are safely preserved by hydroxide layers maintaining their chemical and structural properties.

Computer methods in applied mechanics and engineering 19 (1979) no. 3

In this work, the nickel–aluminum layered double hydroxide (Ni–Al LDH) with nitrate interlayer anion was synthesized and used as a solid phase extraction sorbent for the selective separation and pre-concentration of mefenamic acid prior to quantification by UV detection at λmax=286 nm. Extraction procedure is based on the adsorption of mefenamate anions on the Ni–Al(NO3−) LDH and/or their exchange with LDH interlayer NO3− anions. The effects of several parameters such as cations and interlayer anions type in LDH structure, pH, sample flow rate, elution conditions, amount of nano-sorbent and co-existing ions on the extraction were investigated and optimized. Under the optimum conditions, the calibration graph was linear within the range of 2–1000 µg/L with a correlation coefficient of 0.9995. The limit of detection and relative standard deviation were 0.6 µg/L and 0.84% (30 µg/L, n=6), respectively. The presented method was successfully applied to determine of mefenamic acid in human serum and pharmaceutical wastewater samples.