Cycling properties of Na3V2(PO4)2F3 as positive material for sodium-ion batteries

The research into sodium-ion battery requires the development of high voltage cathodic materials to compensate for the potential of the negative electrode materials which is usually higher than the lithium counterparts. In this framework, the polyanionic compound Na3V2(PO4)2F3 was prepared by an easy-to-scale-up carbothermal method and characterized to evaluate its electrochemical performances in half cell vs. metallic sodium. The material shows a specific capacity (115 mAh g−1) close to the theoretical limit, good coulombic efficiency (>99%) and an excellent stability over several hundred cycles at high rate. High-loading free-standing electrodes were also tested, which showed interesting performances in terms of areal capacity and cyclability.

Taming Polysulfides in an Li–S Battery With Low-Temperature One-step Chemical Synthesis of Titanium Carbide Nanoparticles From Waste PTFE

In this work, titanium carbide (TiC) nanoparticles have been successfully synthesized at much lower temperatures of 500°C using cheaper starting materials, such as waste polytetrafluoroethylene (PTFE) (carbon source) and titanium and metallic sodium, than the traditional carbothermal reduction of TiO2 at 1,800°C. An XRD pattern proved the formation of face-centered cubic TiC, and TEM images showed the obtained TiC nanoparticles with an average size of approximately 50 nm. In addition, the separator coated with TiC nanoparticles as an active material of interlayer effectively mitigates the shuttling problem by taming the polysulfides in Li–S batteries compared with a traditional celgard separator. The assembled cell realizes good cycling stability with 501 mAh g−1 and a low capacity fading of 0.1% per cycle after 300 cycles at 1 C due to high utilization of the sulfur-based active species.

Stable Sodium Metal Anodes with a High Utilization Enabled by an Interfacial Layer Composed of Yolk–Shell Nanoparticles

Metallic sodium (Na) has been regarded as a promising anode for high energy rechargeable batteries owing to its high theoretical specific capacity, low redox potential, and abundant resource. However, Na...

Radiation damage effects on the structure and properties of radioactive waste glasses

The performance assessment of glass matrices currently being used in different nuclear energy producing countries to contain and immobilise high-level waste (HLW) waste is crucial for safe and economic disposal. During the first ~500 years of geological disposal fission products will me the main source or radiation and they decay by beta-gamma emission. We studied different borosilicate glasses used in different countries to immobilise HLW, such as Indian glass (NaBaBSi), UK glasses (LiNaBSi), also called MW- Mixture Windscale, UK-CaZn a modified version of MW, French glass (SON68) and a glass proposed by six collaborating nations, called the International Simple Glass (ISG), to see whether / how irradiation defects are dependent on glass composition. Glasses were externally irradiated using a 60Co gamma source to study the effects of beta-gamma radiation (a gamma emitter loses it energy to atomic electrons they then further interact via coulombic interactions); and by He2+ ion implantation to study the effects of alpha particles. A multi-spectroscopic approach was used to characterise glass specimens before and after irradiation. NaBaBSi and LiNaBSi glasses were irradiated using 60Co gamma photons and we found boron-oxygen hole centres (BOHC), electrons trapped at alkali cations or ET centres and peroxy-radicals (PORs) as common defect in these glasses. In addition, E- or polaron centres which may be related to formation of elemental / metallic sodium colloids formed in NaBaBSi glass. Time-dependent thermal annealing of the irradiated glasses revealed that POR’s are the most thermally stable of the defect centres. BOHC and ET centres were common to SON68, ISG and CaZn glasses. In NaBaBSi, LiNaBSi and SON68 glasses loaded with non-active simulated HLW no sharp and intense signals indicative of radiation-induced paramagnetic defect centres was observed. In the study of NaBaBSi and LiNaBSi glasses doped with 0.19. 0.99, and 4.76 mol% Fe2O3 prepared in an oxidising melting environment, electron paramagnetic resonance (EPR) spectroscopy showed that gamma irradiation induced sharp and intense signals exist for only the 0 and 0.19 mol% Fe2O3 doped samples and disappeared for samples containing higher molar concentrations of Fe2O3. It is postulated that, upon gamma irradiation, in LiNaBSi glass Fe2+ is oxidised to Fe3+ by the capture of holes, whereas in NaBaBSi glass Fe3+ is reduced to Fe2+ due to capture of electrons. Further research is needed to understand the reasons behind these different behaviours.

Alternative anodes for Na-O2 batteries: the case of the Sn4P3 alloy

Alternative anode to metallic sodium based on the high capacity of Sn4P3 alloy is investigated for the first time in Na O2 batteries. This alloy is synthesised by an easy...

Synthesis and Antibacterial, Antioxidant, and Molecular Docking Analysis of Some Novel Quinoline Derivatives

2-Chloroquinoline-3-carbaldehyde and 2-chloro-8-methylquinoline-3-carbaldehyde derivatives were synthesized through Vilsmeier formulation of acetanilide and N-(o-tolyl)acetamide. Aromatic nucleophilic substitution reaction was used to introduce various nucleophiles in place of chlorine under different reaction conditions. The carbaldehyde group was oxidized by permanganate method and reduced with metallic sodium in methanol and ethanol. The synthesized compounds were characterized by UV-Vis, IR, and NMR. The antibacterial activity of the synthesized compounds was screened against two Gram-positive bacteria (Bacillus subtilis ATCC6633 and Staphylococcus aureus ATCC25923) and two Gram-negative bacteria (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853). Most of the compounds displayed potent activity against two or more bacterial strains. Among them, compounds 6 and 15 showed maximum activity against Pseudomonas aeruginosa with mean inhibition zones of 9.67 ± 1.11 and 10.00 ± 0.44 mm, respectively, while ciprofloxacin showed mean inhibition zone of 8.33 ± 0.44 mm at similar concentration. On the other hand, compound 8 exhibited maximum activity against Escherichia coli with inhibition zones of about 9.00 ± 0.55 mm at 300 μg/mL and 11.33 ± 1.11 mm at 500 μg/mL. The radical scavenging activity of these compounds was evaluated using 1,1-diphenyl-2-picryl hydrazyl (DPPH), and all of them displayed moderate antioxidant activity, with compound 7 exhibiting the strongest activity. The molecular docking study of the synthesized compounds was conducted to investigate their binding pattern with DNA gyrase, all of them were found to have minimum binding energy ranging from –6.0 to –7.33 kcal/mol, and the best result was achieved with compound 11. The findings of the in vitro antibacterial and molecular docking analysis demonstrated that the synthesized compounds have potential of antibacterial activity and can be further optimized to serve as lead compounds.

Investigation of structure and electrochemical properties of layered structure NaFexMn1-xO2

Layered oxides are promising electrode materials for sodium-ion batteries, the next generation of rechargeable batteries. The layered oxides with the tránition metallic manganese and iron have paid more attention due to its low-cost, eco-friendly, and facile preparation. In this work, the metallic sodium oxides with a layered structure based on Fe and Mn, NaFexMn1-xO2 (x = 1/3, 1/2 và 2/3) were synthesized via a solid-state reaction at 900 oC for 12–36 hours. All XRD patterns of NaFexMn1-xO2 pointed out the layered structure. In two ratio Fe:Mn = 1/3:2/3 and 1/2:1/2, the synthesized samples presented the P3-layered structure, while in ratio Fe:Mn = 2/3:1/3, the O3-structure was obtained. The lattice parameters were determined by Celref software. The lattice parameters and the volumic of unit cells depended on the ionic radius of cation Mn3+ and Fe3+. The Na-migration was studied by the cycling test with a constant current. The charge-discharge curves and the specific capacity depended on the ratio of Fe:Mn. The specific capacity was found out 120 mAh/g (1/2:1/2), 118 mAh/g (2/3:1/3), and 120 mAh/g (1/3:2/3). After 20 cycles, the capacity was maintained 77 mAh/g (1/2:1/2), 88 mAh/g (2/3:1/3), and 80 mAh/g (1/3:2/3).

Combination of reduction with metallic sodium and adsorption with mesoporous materials for re-refining of used insulating oil via experimental design

In this study oils used direct influence sodium metallic on oxidation products and refining with the Mesoporous silicate material (MCM-41) and also silicate absorbents was synthesized and functionalized with aluminum salt through wet impreghation method (18wt%Al-MCM-41) (36wt% Al-MCM-41). Physical and structural properties has been investigated by FT-IR, BET,XRD and FESEM methods which shows a succful synthesis of the nano porous material. First step for reducing acid number oil we used direct reaction beetwen sodium metalic and used oil, after this step refining used oil by MCM-41 abosrbent has done. The effect of some parameters such as contact time, temperature and the dosage has been determined and optimized by respons surface method (RSM). The results show that acid number decrease obtained 150 ,60min and 200% of dosage. Optimum condation for absorbent reaction products and new oxidation products by MCM-41 obtained contact time of 120min temperature (120oC) and dosage 200% .

Conversion of triphenylphosphine oxide to organophosphorus via selective cleavage of C-P, O-P, and C-H bonds with sodium

For over half a century, thousands of tons of triphenylphosphine oxide Ph3P(O) have been produced every year from the chemical industries as a useless chemical waste. Here we disclose efficient transformations of Ph3P(O) with cheap resource-abundant metallic sodium finely dispersed in paraffin oil. Ph3P(O) can be easily and selectively transformed to three reactive organophosphorus intermediates—sodium diphenylphosphinite, sodium 5H-benzo[b]phosphindol-5-olate and sodium benzo[b]phosphindol-5-ide—that efficiently give the corresponding functional organophosphorus compounds in good yields. These functional organophosphorus compounds are difficult to prepare but highly industrially useful compounds. This may allow Ph3P(O) to be used as a precious starting material for highly valuable phosphorus compounds.