Search

The reductive removal of redox-reactive contaminants, including 2,4-dinitrotoluene, 4-chlorophenol, chromate, and selenate, using biochar-coated metals and the relationship between reduction kinetics and electrochemical properties of biochar-coated metals were examined. To investigate the role of electrochemical properties, one-electron-transfer electrochemical reduction and oxidation mediators were used to determine electron-accepting capacities (EACs) and electron-donating capacities (EDCs) of biochar, zero-valent iron [Fe(0)], FeS, zero-valent zinc [Zn(0)], biochar-coated Fe(0), biochar-coated FeS, and biochar-coated Zn(0). Kinetic analysis showed that biochar coating resulted in decreasing the reductive transformation of contaminants by biochar-coated metals, suggesting that the sorbed molecules were further reduced to reduction products. Biochar, metals, and biochar-coated metal EDCs were an order of magnitude higher than their EACs, ranging between 11.01 and 38.61 mmol e−/g. The linear relationship between the EDCs and kinetic rates revealed that electron transfer from the core metal to sorbed contaminant oxidation is responsible for the reductive removal. A significant and irreversible EDC decrease generates electrons for the reductive transformation. To our knowledge, it is the first attempt to examine the electrochemical properties of metal-biochar composites and their relationship with reduction kinetics of various contaminants. Our results indicate that biochar-coated metals can be used as a sorbent and reductant for redox-reactive contaminants in subsurface environments.

NiCo2S4 nanoparticles (NPs) were dry coated on LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode using a resonant acoustic coating technique to produce all-solid-state lithium batteries. The NiCo2S4 coating improved the electrochemical properties of the NCM622 cathode. In addition, NiCo2S4 eliminated the space-charge layer and the cathode showed an excellent affinity with the interface with a sulfide-based solid electrolyte as an inert material. X-ray diffraction patterns of NCM622 coated with NiCo2S4 showed the same peak separations and lattice parameters as those of bare NCM622. Field-emission scanning electron microscopy and electron dispersive spectroscopy mapping analyses showed that 0.3 wt% NiCo2S4-coated NCM622 had an evenly modified surface with NiCo2S4 NPs. X-ray photoelectron spectroscopy (XPS) revealed that the surface of 0.3 wt% NiCo2S4-coated NCM622 had two different S 2p peaks, a Co–S peak, and Ni and Co peaks, compared to those of bare NCM622. Electrochemical studies with electrochemical impedance spectroscopy and galvanostatic charge–discharge cycle performances showed that NiCo2S4-coated NCM622 retained a higher specific capacity over multiple cycles than bare NCM622. Especially, 0.3 wt% NiCo2S4-coated NCM622 exhibited a capacity retention of 60.6% at a current density of 15 mA/g for 20 cycles, compared to only 37.3% for bare NCM622. Finally, interfacial XPS and transmission electron microscopy-electron energy loss spectroscopy analyses confirmed the stable state of 0.3 wt% NiCo2S4-coated NCM622 with minimal side reactions.

Li7P3S11 (LPS) solid electrolytes have great advantages, such as high lithium-ion conductivity, and can easily fabricate to make bulk-type all-solid-state lithium batteries. However, LPS has a disadvantage because of large interfacial resistance with lithium, which give a limitation for all-solid-state battery. In this study, (100-x)Li7P3S11-x Li3SI (x = 0. 2 and 5) solid electrolyte composites are prepared by mechanical ball milling process. Various physiochemical analysis was carried out to confirm the proper mixing of Li7P3S1 and Li3SI solid electrolytes. The addition of Li3SI solid electrolyte, effectively influence the ionic conductivity and electrochemical properties of the Li7P3S1 solid electrolyte. The prepared Li7P3S11/Li3SI solid electrolyte composites are stable against the lithium metal anode even after 100 h charge-discharging process and has stable potential window up to 10 V. In particular, 98Li7P3S11-2Li3SI solid electrolyte based ASSLBs shows the highest capacity, of 110 mA/g at the current density of 7.5 mA g−1 (0.05 C). The charge – discharge cycle stability test also proved the Li3SI mixing to Li7P3S11 helped to maintain the capacity retention value of ∼100 % after 10 cycles. Therefore, the Li3SI into the Li7P3S11 electrolyte helps improve the electrochemical performance.

A new silver halide-doped Li7P3S11 (7Li2S–3P2S5) solid electrolyte with increasing ionic conductivity and stability was prepared by the wet ball milling process. Detailed structural investigations ...

We studied the efficiency of different particle-sized sulfide solid electrolyte-based cathode composites. First, we prepared the Li7P2S8I solid electrolytes with different particle sizes through a high energy ball milling process and solution method. The structural details of the prepared solid electrolytes were studied by powder X-ray diffraction. The surface morphologies and particle size of the electrolytes were studied by field emission electron microscopy. The ionic conductivity of the prepared solid electrolytes was studied by the electrochemical impedance spectroscopy technique. Finally, we have prepared a LiNi0.8Co0.1Mn0.1O2 (NCM 811) based cathode composite and studied the electrochemical performance of the fabricated all-solid-state lithium batteries. The mixed particle-sized solid electrolyte-based cathode composite exhibited higher specific capacitance (127.2 mA h g−1) than the uniform-sized solid electrolyte-based cathode composite (117.1 mA h g−1). The electrochemical analysis confirmed that the sulfide solid electrolytes with mixed particle size exhibited better electrochemical performance.

Li7P3S11 solid electrolytes with high lithium-ion conductivity are promising candidates for use in all-solid-state lithium batteries. However, this electrolyte's poor interfacial compatibility with lithium electrodes causes unstable cyclability. In this study, in order to address this problem, (100−x)Li7P3S11-xLi2OHBr (x = 0, 2, 5, 10, 20, 30, 40, and 50) electrolytes are prepared by a high energy ball-milling technique and heat-treatment process. The resulting (100−x)Li7P3S11-xLi2OHBr (x = 2, 5, 10, 20, 30, 40, and 50) electrolytes provide improved electrochemical performance with good cycling stability and a wide electrochemical window of up to 10 V (vs. Li/Li+). Moreover, these electrolytes have high ionic conductivity of 10−4–10−5 S/cm at room temperature. Particularly, the 90Li7P3S11-10Li2OHBr electrolyte displays the highest conductivity of 4.4 × 10−4 S/cm at room temperature as well as improved cyclability. Moreover, 90Li7P3S11-10Li2OHBr shows decreased interfacial resistance between the solid electrolyte and cathode electrode, which was revealed by Electrochemical Impedance Spectroscopy (EIS) analysis. The initial discharge capacity of 90Li7P3S11-10Li2OHBr was found to be 135 mAh/g when used in a In|solid electrolyte|Li(Ni0.6Co0.2Mn0.2)O2 all-solid-state lithium battery (ASSLB). Thus, we can conclude the addition of Li2OHBr into the Li7P3S11 results in enhanced electrochemical properties.

The objective of this study was to prepare Ce–MnO2 nanostructure composite as an electrode material for supercapacitor application. Ce–MnO2 nanostructure composite was synthesized by facile hydrothermal method at different temperatures. Structural details of pure and Ce–MnO2 nanostructure composite were studied using powder X-ray diffraction technique. The formation of flower like structure and strong interaction with Ce and MnO2 were confirmed by field emission electron microscope technique. Their electrochemical performances were elucidated by using cyclic voltammetry, charge–discharge, and electrochemical impedance spectroscopy techniques. Nearly rectangular shaped cyclic voltagram was observed for synthesized Ce–MnO2 nanostructure composite electrode, indicating the existence of electric double layer capacitance nature. Ce–MnO2 (130) nanostructure composite exhibited high specific capacitance value of 147.25 F/g at applied current density of 1 A/g in 1 M Li2SO4 aqueous electrolyte. Furthermore, resistive and capacitive behaviors of these electrodes were studied from Nyquist and bode diagrams within frequency range of 10 mHz to 100 kHz.

Treatment of Leishmaniasis is always not satisfactory despite advancement all these years. This chapter will discuss the standard treatment options like Amphotericin, oral miltefosine, topical paromycin, add more details about newer emerging drugs and alternative therapies, surgical treatment modalities for resistant cases. Will discuss few information regarding vaccines. Special precautions to be taken while travelling to endemic areas will be discussed. Management protocol for mucocutaneous and visceral type will be highlighted. Side-effects of drugs used in the treatment of Leishmaniasis will be discussed in short and measures to monitor these side effects will be discussed. Long term monitoring of relapse will also be discussed.

We tried to improve the ionic conductivity, lithium-ion diffusion, and cycle capacity of pure β-LiVOPO4 cathode material by Zr doping. Pure and Zr-doped β-LiVOPO4 cathode material was synthesized by a low-temperature sol–gel process. The physiochemical properties of the synthesized materials were analyzed by various characterization techniques. The Zr doping of the β-LiVOPO4 was confirmed by ex situ XANES analysis. The electrochemical behavior of the synthesized material was studied by various electrochemical analyses. The lithium-diffusion coefficient values of pristine and selected Zr-doped β-LiVOPO4 cathode materials were studied and compared using SSCV, EIS, and PITT at different voltages. The calculated values of the diffusion coefficients obtained from CV and EIS are in the range of 10−14–10−13 cm2/s. The PITT measurement gives the values of 10−12–10−11 cm2/s. All techniques indicated that x = 0.03 Zr-doped samples obtained the improved the lithium diffusion coefficient values.

The 3Li2S-P2S5:xLiCl:(1-x)LiI solid electrolytes were prepared via solution process using acetonitrile, and crystallization was achieved by heating at 160 °C for 3 h. The crystalline nature and morphology of the prepared materials were studied using powder X-ray diffraction and field emission scanning electron microscope analysis. Cyclic voltammetry was performed to confirm the electrochemical stability of the electrolytes. The ionic conductivity of the prepared 3Li2S-P2S5:0.25LiCl:0.75LiI solid electrolyte was 1.32 × 10−4 S cm−1, at room temperature. In addition, the prepared 3Li2S-P2S5:0.25LiCl:0.75LiI solid electrolyte showed better electrochemical stability comparable to that of prepared pure 3Li2S-P2S5, and other Cl and I mixed solid electrolytes.

Feasibility tests of iron-biochar composites for removal of chromate (CrO42−) and selenate (SeO42−) were conducted through a series of batch experiments. Two types of iron-biochar composites were synthesized using zero-valent iron [Fe(0)] and Fe3O4 via co-pyrolysis with rice straw. Fe(0)-biochar composites removed chromate and selenate via sorption and reduction. Even biochar alone could reduce selenate to selenite and its reduction products, probably due to localized electrons in biochar. The Fe3O4-biochar composite did not effectively remove chromate and selenate, nor did dissolved humic acid and salts affect the removal of chromate and selenate by the Fe3O4-biochar composite. In contrast, changes in pyrolysis temperature and pH enhanced the removal. The iron-biochar composites and biochar alone may be sustainable long-term options for remediation of toxic anionic metals in natural environments.

We develop a new solution synthesis strategy for producing high ionic-conducting sulfide solid electrolyte using ethylenediamine (EDA) solvent. Here, we follow three simple steps: dissolve the precursor in ethylenediamine solvent to form the clear solution, then removing a solvent at 180 °C followed by heat treatment. The prepared Li5.5MPS4.5Cl1.5 electrolyte demonstrated the high ionic conductivity of 2.87 mS cm-1 at 25 °C. Further, fabricated solid battery using optimized electrolyte exhibited a high initial discharge capacity of 175.7 mAh g-1 at 0.1 C rate. Moreover, the synthesis technique is a convenient and quick process, thus facilitating mass production of solid electrolytes.

To enhance the removal of redox-reactive contaminants, biochars including FeS and Zn(0) were developed via pyrolysis. These biochars significantly promoted the removal of 2,4-dichlorophenol (DCP) by means of sorption and reduction. Compared to direct reduction with FeS and Zn(0), the formation of reduction intermediates and product was enhanced from 21% and 22% of initial DCP concentration to 41% and 52%, respectively. 2,4-Dinitrotoluene (DNT), chromate (CrO42−) and selenate (SeO42−) were also reductively transformed to reduction products (e.g., 2,4-diaminotoluene [DAT], Cr3+, and selenite [SeO32−]) after they sorbed onto the biochars including FeS and Zn(0). Mass recovery as DAT, Cr3+ and selenite was 4–20%, 1–3%, and 10–30% under the given conditions. Electrochemical and X-ray analyses confirmed the reduction capability of the biochars including FeS and Zn(0). Fe and S in the FeS–biochar did not effectively promote the reductive transformation of the contaminants. Contrastingly, the stronger reducer Zn(0) yielded faster reductive transformation of contaminants over the Zn(0)-containing biochar, while not releasing high concentrations of Zn2+ into the aqueous phase. Our results suggest that biochars including Zn(0) may be suitable as dual sorbents/reductants to remediate redox-reactive contaminants in natural environments.

We report the synthesis of MnO2 nanostructures with MnS deposits via a facile one-step hydrothermal process for high-performance supercapacitor applications. In comparison to pure MnO2 nanoflowers, MnS deposition substantially alters the morphology of the MnO2 nanoflowers with respect to the addition of the sulfur source. The crystalline nature and changes in morphology of the synthesized composite materials were confirmed by powder XRD and FESEM analysis. The electrochemical behaviors were examined by cyclic voltammetry, charge–discharge and electrochemical impedance spectroscopy techniques in 1 M Na2SO4 aqueous electrolytes. The 3MnS/MnO2 nanocomposite exhibits a relatively high specific capacitance of 384.25 F g−1 at a current density of 1 A g−1, which is nearly two-fold higher than that of pure MnO2 nanoflowers (204.25 F g−1). A symmetric capacitor was fabricated using the 3MnS/MnO2 nanocomposite and activated carbon as positive and negative electrodes, respectively. The resulting asymmetric device exhibits a specific capacitance of 84.56 F g−1 at a current density of 0.5 A g−1 and a cycle stability of ∼87% after 1000 charge–discharge cycles.

A novel (Nb4O5–TiO2)@rGO nanocomposite was synthesized using a Na+ ion intercalation-assisted hydrothermal technique and examined its photocatalyst dye degradation and supercapacitor applications. The synthesized (Nb4O5–TiO2) nanorods were segregated by well dispersed reduced graphene oxide with different weight ratios. A strong interaction was observed between the (Nb4O5–TiO2) to rGO nanosheets, even with high rGO content (5 wt. %). Experiments examining the photocatalytic degradation of methylene blue suggested that the (Nb4O5–TiO2)@ 5rGO nanocomposites exhibit excellent charge carrier mobility with a higher methylene blue degradation rate (92%) than Nb4O5–TiO2 nanorods and other (Nb4O5–TiO2)@rGO nanocomposites under ultraviolet and visible light irradiation. On the other hand, the (Nb4O5–TiO2)@ 5rGO nanocomposite exhibited excellent electrochemical performance with high specific capacitance (365 F g−1), long cycling stability (∼100% capacitance retention after 1000 cycles), and good rate capability (70% capacitance retention at 25 A g−1). In addition, the photocatalytic and supercapacitor efficiency of the (Nb4O5–TiO2)@rGO nanocomposite increased gradually with increasing amount of rGO in the composite. These features collectively demonstrated the high rate of photocatalytic degradation efficiency and good energy storage performance of the (Nb4O5–TiO2)@ 5rGO nanocomposite, which suggests a new route for large scale applications in energy and environmental fields.

This paper reports the synthesis of lanthanum oxide/hydroxide nanoparticle (LaNPs)-doped rGO nanosheets. The uniform distribution of LaNPs on the rGO nanosheets was confirmed by FESEM, TEM, and elemental analysis. A dramatic change in electrochemical behavior was observed by adjusting the concentration of LaNPs in rGO (LaG ratio = 1:2, 1:1 and 2:1). The LaG 12 showed a better areal capacitance of 889.29 F cm−2 than LaG 11 (428.58 F cm−2) and LaG 21 (260.72 F cm−2). Further, improved cycle stability (84% after 1000 cycles) with good impedance behavior confirms LaG 12 is a suitable electrode material for high-performance supercapacitor fabrication.

Sulfide-based lithium superionic conducting solid electrolytes for all-solid-state lithium batteries have received much attention due to their high safety, ionic conductivity, and compatibility. However, high-temperature treatment over a long time is needed to achieve high ionic conductivity. In this work, we have prepared the dual-halide-based Li7P2S8X type lithium superionic conductors by dry ball mill process and the high ionic conducting phase was achieved by low temperature (200℃) heat-treatment process. High ionic conducting halogen-halogen composition was arrived at through a series of optimization processes. Among the compositions tested, the Li7P2S8Br0.25I0.75 solid electrolyte exhibited a high ionic conductivity value of 6.16 mS cm−1, at room temperature. The ionic radius of the halogen element played an important role in the formation of the high ionic conducting phase. Further, the ionic conductivity of Li7P2S8I0.75Br0.25 solid electrolyte was improved by metal doping at P-site. The Sn-doped Li7P2S8I0.75Br0.25 solid electrolyte exhibited a high ionic conductivity value of 7.78 mS cm−1, at room temperature. The addition of large-sized Sn atoms extended the crystal lattice parameters and increased the Li-ions transport path. The partial substitution of Sn atoms at P-site was confirmed by NMR and Laser Raman analysis. The electrochemical stability of the prepared solid electrolyte was studied by cyclic voltammetry and DC charge-discharge analysis. The addition of a metal atom to the Li7P2S8Br0.25I0.75 solid electrolyte decreased the side reaction with the Li metals. Thus, low-temperature treated metal-doped Li7P2S8Br0.25I0.75 solid electrolytes are highly favourable for the fabrication of high-performance all-solid-state batteries. The fabricated all-solid-state battery using Sn doped Li7P2S8Br0.25I0.75 solid electrolyte exhibited the high specific capacity value of 170 mAh g−1 (0.1C), at room temperature.

Nanostructured MnO2 was synthesized using a facile hydrothermal technique with potassium permanganate as a precursor. Rare earth elements, lanthanum and cerium, were used to control the porosity of the MnO2 nanostructures. Nanorod-, nanoflower-, nanoneedle-, and nanoneedles/nanopetal-shaped MnO2 nanostructures were synthesized by changing the concentration of the rare earth elements. The as-synthesized MnO2 nanorods, La – MnO2 nanoneedles, Ce – MnO2 nanoflowers, and La/Ce – MnO2 nanoneedles/nanopetals were examined using a range of physico chemical characterization techniques. Scanning electron microscopy and transmission electron microscopy – energy dispersive X-ray spectroscopy confirmed the morphology of the MnO2 nanostructures and the elemental distribution. The porous natures of the synthesized MnO2 nanostructures were analyzed by nitrogen adsorption technique. The electrochemical behavior of the MnO2 nanostructures was examined by cyclic voltammetry, charge – discharge and electrochemical impedance spectroscopy tests. The La/Ce – MnO2 nanoneedles/nanopetals electrode exhibited a high specific capacitance of 825 F g−1 at an applied current density of 10 A g−1. The La/Ce – MnO2 nanoneedles/nanopetals were also mixed with 5, 10, 15 and 20 wt% of rGO nanosheets to enhance the electrochemical behavior. The 20 rGO@La/Ce – MnO2 sample showed extraordinary electrochemical behavior; the calculated specific capacitance was 1165 F g−1 at an applied current density of 10 A g−1. A 20 rGO@La/Ce – MnO2 and activated carbon asymmetric supercapacitor coin cell device exhibited ∼93% capacitance retention after 1000 cycles. These results highlight the potential of 20 rGO@La/Ce – MnO2 as an electrode material for supercapacitor applications.

Lithium solid state batteries are one of the state of the art energy storage systems due to their high safety. However, ionic conductivity in solid electrolytes is a concern, because at present it does not match the ionic conductivity of non-aqueous Li-ion batteries, thus resulting in sluggish electrochemical kinetics. In this report, we enhance the ionic conductivity of Li-argyrodites (Li6PS5Cl0.5Br0.5) through Si substitution at the P-site using a dry ball milling process. Among the silicon substitutions, Li6.2Si0.2P0.8S5Cl0.5Br0.5 exhibited the high ionic conductivity of 5.12 mS cm−1 compared to pristine Li6PS5Cl0.5Br0.5 at 4.02 mS cm−1. The Rietveld refinement analysis revealed that after silicon substitution, volume of the unit cell gets increased that allows the lithium at T2-site, that promotes the fast Li-ion transport. Moreover, the optimized solid electrolyte was utilized in a solid state battery system, and demonstrated a high initial capacity of 148.1 mAh g−1 at 0.1 C rate compared to pristine argyrodite (135.1 mAh g−1). Further, we demonstrated the interface phenomena between electrode and solid electrolyte using ex-situ XPS analysis. This confirmed the formation of interface products such as LiCl, Li2S, lithium polysulfides and P2Sx, which influence the cycling stability of the ASSLBs.