Lanthanum-substituted CaMo-MOF via controlled metal nitrate ratios for Electrochemical Performance

The use of metal nitrate-modified amorphous nano silica for synthesizing solid amine CO2 adsorbents with resistance to urea linkage formation

Optimizing the electrochemical performance of Li2MnO3 cathode materials for Li-ion battery using solution combustion synthesis: Higher temperature and longer syntheses improves performance

Coprecipitation of copper/zinc compounds in metal salt–urea–water system

Micro/nanohybrid materials have vast applications due to their great potentialities in the field of nanoscience and nanotechnology. Herein we report an investigation on the fabrication and physicochemical characterization of ceramic (Fe0.01La0.01Al0.5Zn0.98O) and hybrid ceramic-polyaniline nano-composits. Ceramic nano-particles were prepared by sol-gel technique while optimizing the molar ratios of the constituent's metal nitrates. The prepared inorganic particles were then embedded in the polymer matrix via one-pot blending method. The prepared ceramic particles and their composites with polyaniline were analysed under FT- IR, SEM and TGA. The presence of some chemical species was observed at the interface of the compositing materials. TGA analysis showed the thermal stability of the composite material. Frequency dependent dielectric properties were analysed and it was found that conducting polyaniline has an additional effect on the electrical behaviour of the composite. Rheology study showed enhanced mechanical properties of composite material as compared to their constituting counterparts.

We report here the influence of citric acid concentration on the formation of sol-gel products in each of Cu and Zn systems by using respective metal nitrate as precursor and citric acid as gelling agent. The synthesized sol-gel products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX), Fourier transform infra-red (FT-IR) spectroscopy and UV-Visible diffused reflectance spectroscopy (UV-Vis DRS). The influence of citric acid concentration on the formation of metal/metal oxide in each case was primarily investigated by varying the molar ratio of each metal nitrate (N) and citric (C) acid (N:C = 1:1, 1:2, 1:4, 1:6 and 1:8). It was observed that at low N:C molar ratios (1:1) and (1:2), the Cu system had only CuO and at high N:C molar ratio, lower oxidation state of copper (Cu2O and Cu) has resulted. Distinctly, irrespective of the N:C molar ratio, the sol-gel product of Zn system was only single phase of ZnO. The SEM observations confirmed that the grains of these two metal systems were spherical in nature. In each metal system, at high N:C molar ratio, small grain size has resulted. At high N:C ratio, lower oxidation state of metal ion is resulted where the metal system is susceptible for reduction. The susceptibility of metal ions to undergo reduction controlled the formation of end products in the sol-gel process.

SrAl2O4:Eu2+,Dy3+ long persistence phosphors are synthesized by combustion method. The effects of several processing conditions such as the mole ratio of urea and metal nitrates, initiating temperature, the amounts of fluxing agent(boric acid), and raw material ratio（Sr:Al）on phase composition and subsequent on the spectroscopic properties are studied. The results show that the phase composition changed from strontium-rich phase to aluminium-rich phase with the increasing of initiating temperature, the increasing of the content of urea and boric acid, and with the decreasing of Sr:Al. The results indicate that the sample has most excellent luminescence performance is not the one which has pure single phase SrAl2O4, but the one has little impurity phase SrAl4O7. Similar phenomenon is also present when synthesized by high temperature solid-state method and microwave plasma synthesis method, so the differences among three methods are also discussed in this paper.

Highly porous zinc ferrite (ZnFe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O4) nano-size powders are synthesized by varying fuel to oxidizer ratio. The metal nitrates are used as oxidizers while glycine is used as a fuel. The synthesis of material is carried out using an auto-combustion method. It is observed that the enhancement of magnetization occur with the enhancement of 'Fuel to Oxidizer' ratio i.e. Glycine to metal Nitrate (G/N) ratio. The structural, morphological, and magnetic features of samples are studied using XRD, SEM, EDAX, BET and VSM techniques. At the microscopic level, the materials exhibit a formation of spongelike structure containing nano-size particles. The XRD measurements confirm the formation of single phase spinel structure of zinc ferrite (ZnFe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> ). As a case study, the response of materials to ethanol gas is studied. It is observed that higher G/N ratio lead to lowering of gas sensitivity as well as operating temperature. The results are discussed in terms of reactions of surface oxygen with ethanol gas.

Variations in an oleic acid and metal nitrate emulsion under calcination on the structural and morphology of LaAlO 3 nanopowders

We report herein on the synthesis of “layered-layered” integrated materials (, 0.5, and 0.7) using the self-combustion reaction in solutions containing metal nitrates and sucrose. The nanoparticles of these materials were obtained by further annealing of the as-prepared product in air at for 1 h and submicrometric particles were obtained by further annealing at for 22 h. The effect of composition on the electrochemical performance was explored in this work. By a rigorous study with high resolution transmission electron microscopy (HRTEM), it became clear that the syntheses with the above stoichiometries produce two-phase materials comprising nanodomains of both rhombohedral -like and monoclinic structures, which are closely integrated and interconnected with one another at the atomic level. Stable reversible capacities were obtained with composite electrodes containing submicrometer particles of . Structural aspects, activation of the monoclinic component, and stabilization mechanisms are thoroughly discussed using Raman spectroscopy, solid-state NMR, HRTEM, and X-ray diffraction (including Rietveld analysis) in conjunction with electrochemical measurements. This work provides a further indication that this family of integrated compounds contains the most promising cathode materials for high energy density Li-ion batteries.

Metallic sodium (Na) has been regarded as one of the most attractive anodes for Na-based rechargeable batteries due to its high specific capacity, low working potential, and high natural abundance. However, several important issues hinder the practical application of the metallic Na anode, including its high reactivity with electrolytes, uncontrolled dendrite growth, and poor processability. Metal nitrates are common electrolyte additives used to stabilize the solid electrolyte interphase (SEI) on Na anodes, though they typically suffer from poor solubility in electrolyte solvents. To address these issues, a Na/NaNO3 composite foil electrode was fabricated through a mechanical kneading approach, which featured uniform embedment of NaNO3 in a metallic Na matrix. During the battery cycling, NaNO3 was reduced by metallic Na sustainably, which addressed the issue of low solubility of an SEI stabilizer. Due to the supplemental effect of NaNO3, a stable SEI with NaNxOy and Na3N species was produced, which allowed fast ion transport. As a result, stable electrochemical performance for 600 h was achieved for Na/NaNO3||Na/NaNO3 symmetric cells at a current density of 0.5 mA cm-2 and an areal capacity of 0.5 mAh cm-2. A Na/NaNO3||Na3V2(PO4)2O2F cell with active metallic Na of ∼5 mAh cm-2 at the anode showed stable cycling for 180 cycles. In contrast, a Na||Na3V2(PO4)2O2F cell only displayed less than 80 cycles under the same conditions. Moreover, the processability of the Na/NaNO3 composite foil was also significantly improved due to the introduction of NaNO3, in contrast to the soft and sticky pure metallic Na. Mechanical kneading of soft alkali metals and their corresponding nitrates provides a new strategy for the utilization of anode stabilizers (besides direct addition into electrolytes) to improve their electrochemical performance.

Crystal habits of LiMn2O4 and their influence on the electrochemical performance

Rechargeable batteries can store energy in the form of chemical energy and facilitate it with a high conversion rate when needed. Moreover, rechargeable batteries are used in almost all kinds of portable consumer electronics, hybrid and pure electric vehicles. Thus, the development of advanced battery technologies is a major field of scientific focus. Li-ion technology has been shown to be superior compared to other battery concepts in performance, cycling stability, self-discharge and expected lifetime.[1] However, commercially used cathode materials (LiMO2) exhibit low capacities compared to the graphite based anodes (~300 mAh/g) and thus limits the battery performance. In the last decade polyanion based materials gained interest and in 2005 Nyten et al. reported on Li2FeSiO4as a new Li-battery cathode material [2]. Lithium transition-metal silicate based materials are promising candidates for next generation’s Li-ion batteries since they allow Li extraction/insertion beyond one Li ion per formula unit. Furthermore, they consist of cheap, non-toxic and abundant elements [3].This work focuses on Li2MnSiO4 (LMS), which can theoretically deliver two Li-ions per formula unit since the transition metal ion possesses two redox couples (Mn3+/Mn2+ + Mn4+/Mn3+). Synthesis of phase pure LMS material has, however, turned out to be challenging. Here, synthesis of LMS with high phase purity was demonstrated by an acidic, PVA assisted sol-gel method using metal nitrates and TEOS as precursors, which is also suitable for upscaling. The dried precursor was pre-calcined and then mixed with a given amount of corn-starch as carbon source. To obtain the desired phase and coat the material in a single step, the powder/starch mix was then carbothermally reduced at 700 °C for 10 h. The atmosphere and starch content are seemingly crucial in both heat treatments to achieve high phase purity in the final cathode powder. Best results were achieved when both heat treatments were carried out in 95% Ar 5% H2 and with starch contents ≥ 25 wt-%. Figure 1 shows powder XRD patterns of LMS with optimized parameters and different starch contents and a full pattern refinement.The synthesized materials were micro- and meso-porous powders with a thin uniform carbon coating (confirmed by TEM), offering high external surface areas of more than 30 m2g-1 (excluding micropore area which is inaccessible to the electrolyte). In addition to pure Li2MnSiO4, this work also focuses on the synthesis and electrochemical performance of Fe and V substituted LMS. Fe substitution should provide increased cycling stability since Li2FeSiO4 has shown relatively good long-term stablility [2,3]. The doping of V on either the Mn or the Si site of LMS is currently under investigation. V doped LMS is believed to offer improved electrochemical performance since V offers 3 redox couples in the accessible voltage window of the electrolyte of a Li-ion battery [4].[1] Tarascon, J. M., Armand, M, Issues and challenges facing rechargeable lithium batteries, Nature, 2001, 414, 359-367.[2] Nyten A., Abouimrane A., Armand M., Gustafsson T., Thomas J. O., Electrochemical performance of Li2FeSiO4 as a new Li-battery cathode material, Electrochemistry Communications, 2005, 7, 156-160.[3] Saiful Islam M., Dominko R., Masquelier C., Sirisopanaporn C., Armstrong A. R., Bruce P. G., Silicate cathodes for lithium batteries: alternatives to phosphates?, J. Mater. Chem., 2011, 21, 9811-9818[4] Li, Y, Cheng, X, Zhang, Y, Achieving High Capacity by Vanadium Substitution into Li2FeSiO4, Journal of The Electrochemical Society, 2012, 159 (2) A69-A74.

Nanomaterials have attracted significant attention in recent decades for their diverse applications, including energy storage devices like supercapacitors. Among these, cobalt oxide (Co3O4) nanostructures stand out due to their high theoretical capacitance, unique electrical properties, and tunable morphology. This study explores the hydrothermal synthesis of Co3O4, revealing that the molar ratio of cobalt nitrate to potassium hydroxide significantly influences the morphology, crystal structure, and electrochemical performance. An optimized 1:1 molar ratio (COK 11) yielded well-defined cubic nanostructures with uniform elemental distribution, as confirmed by SEM, TEM, and EDS analyses. Structural characterization through XRD, XPS, and FTIR validated the formation of the Co3O4 spinel phase with distinctive lattice and surface oxygen features. Electrochemical property analysis demonstrated the superior performance of the COK 11 electrode, achieving a high specific capacity of 825 ± 3 F/g at a current density of 1 A/g, a rate capability of 56.88%, and excellent cycle stability of 88% at 3 A/g after 10,000 cycles. These properties are attributed to the nano-cubic morphology and interconnected porosity, which enhanced ion transport and active surface area. This study highlights the importance of synthesis parameters in tailoring nanomaterials for energy storage, establishing COK 11 as a promising candidate for next-generation high-performance supercapacitor applications.

A series of metal-organic frameworks (MOFs) based on isonicotinic acid and nickel nitrate were successfully synthesized by a solvothermal method as electrode materials for supercapacitor. The MOF were examined by X-ray diffraction (XRD) patterns and N2 adsorption/desorption isotherms. Electrochemical properties of the materials were characterized by cyclic voltammetry (CV) in 6 M KOH aqueous solutions. The effect of solvothermal time, temperature and the mol ratio of isonicotinic acid and nickel nitrate on the electrochemical performance were also studied. The maximum specific capacitance is found to be 634 F g−1 at 5 mV s−1 and the stable cycling properties measurement showed the sample kept 84% after 2000 cycles at a 50 mV s−1 scan rate.

Electrochemical performance and enhanced nitrate removal of homogeneous polysulfone-based anion exchange membrane applied in membrane capacitive deionization cell