Ionic transport and battery characterization studies in (30-x)Na2O  xNaF60B2O310Tl2O glasses

The results from measurements of the d.c. electrical conductivity of the Na₂ONaFB₂O₃Tl₂O glass system and the transference number are reported. Electrochemical cells with the configuration Na/(30Na₂O60B₂O₃10Tl₂O)/(graphite + iodine + electrolyte) have been fabricated and the discharge characteristics examined. The open-circuit voltage and the short-circuit current (maximum) are 2.27 V and 2.19 mA, respectively. Several other cell parameters are reported.     

Ionic (O2−, H+) transport in novel Zn-doped perovskite LaInO3

For the first time the LaIn_1-xZn_xO_3-1/2x samples was synthesized via solid-state reaction method. The Zn²⁺−doping effect on the B-site of LaInO₃ on structure, water uptake and electrical properties was investigated. The results show that Zn²⁺ is good alternative to alkaline earth metals. The Zn-doping decreases the sintered temperature and makes it possible to obtain high-density ceramics. The substitution increases the conductivity by ∼2 orders of magnitude. Below ∼500 °C the phases exhibit the dominant oxygen-ionic transport (dry atmosphere), and the dominant protonic transport below 600 °C (wet atmosphere). The obtained results suggest the prospects for using these materials in the Hydrogen Energy field. A new concept of the ability of perovskite phases LaBO₃ to incorporate water has been proposed. In addition to the presence of oxygen vacancies, their size, which depends on the B-cation nature, is of decisive importance in the hydration process and the formation of proton conductivity.     

Conductivity and parametric studies of a (PEO+(glass)(15Na2O–15NaF–70B2O3)) cell

Ion conducting polymer electrolyte films based on poly(ethylene oxide) (PEO) complexed with a glass (15Na₂O–15NaF–70B₂O₃) are prepared by a solution—cast technique. The complexation of the glass with PEO is confirmed by X-ray diffraction analysis. DC conductivity in the temperature range 303–373 K and transference number measurements are performed in order to investigate the charge transport in the polymer electrolyte system. The conductivity of the (PEO+glass) electrolyte is about 10⁴ times larger than that of pure PEO at room temperature. The transference number data show that the charge transport in this polymer electrolyte system is predominantly due to ions. Using these polymer electrolytes, solid-state electrochemical cells are fabricated. Various parameters associated with these cells are evaluated and compared with those of other reported cells.     

Alkali insertion within NiONi electrode in contact with molten Li2CO3K2CO3 and Li2CO3Na2CO3K2CO3 at 650°C

Lithium, sodium and potassium species have been analysed by different spectroscopic techniques in the NiO layer recovering nickel cathode used in the state-of-the-art molten carbonate fuel cell. The nickel electrode was previously oxidized in lithium-containing carbonate electrolytes, Li₂CO₃K₂CO₃ and Li₂C0₃Na₂CO₃K₂CO₃ at 650°C. Similarly to the well-known case of lithium, it has been shown that the presence of sodium and potassium cations could be associated to their insertion in the NiO lattice.     

Effect of KOH concentration and anions on the performance of an NiH2 battery positive plate

The capacity and voltage behavior of electrochemically impregnated sintered nickel positive plates was examined by galvanostatic charging and discharging in a flooded electrolyte cell. Three different concentrations of potassium hydroxide (KOH) (40%,31% and 26%) and 31% KOH containing dissolved nitrate, sulfate, or silicate were investigated. The end-of-charge voltage at $\text{C}\text{10}$ charge and at 10°C showed the following order: 40% KOH > 31 % KOH alone, and in the presence of the anions > 26% KOH. The mid-discharge voltage at $\text{C}\text{2}$ discharge was higher in 26% KOH, almost the same for 31%Ao KOH with and without the added contaminants, and much lower for 40% KOH. The plate capacity was marginally affected by cycling in all cases except for 40% KOH, where the capacity declined after 1000 cycles at 80% depth-of-discharge (DOD). At the end of cycling all the plates tested experienced a weight loss, except in the case of 31% KOH, as a result of active material extrusion. Cyclic voltammetry of miniature electrodes in 31% KOH showed that the cathodic peak potentials are less polarized at −5 °C (compared to 25 °C) in the presence and absence of silicate. This indicates a slightly higher voltage during discharge in an NiH₂ battery. Furthermore, the features of the current-potential profile were practically unchanged in the presence of silicate.     

Research on optimization and performance of Na2HPO4·12H2O mixture system combining fuzzy optimization model based on analytic hierarchy process

In order to determine optimal salt hydrates matching and adding fraction of Na₂HPO₄ · 12H₂O, crystal characteristics, latent heat of phase change, supercooling degree, and phase change temperature were studied. According to experimental data, optimal salt hydrates matching and adding fraction of Na₂HPO₄ · 12H₂O are determined by adopting multi-objective fuzzy optimization model based on analytic hierarchy process. Aimed at 3% Na₂SiO₃ · 9H₂O-Na₂HPO₄ · 12H₂O optimized by the method, thermal cycling performance test is implemented. Test results show the following: the Na₂SiO₃ · 9H₂O-Na₂HPO₄ · 12H₂O system has lower supercooling degree than Na₂HPO₄ · 12H₂O. It forms stable crystal after multiple thermal cycles, the phase separation is eliminated completely, and supercooling degree is 3.6°C. Latent heat of phase change maintains at 164 J/g after 100 thermal cycles. It is a modified intermediate product of salt hydrates with development potential.     

Studies on metal oxides suitable for enhancement of the O2-releasing step in water splitting by the MnFe2O4–Na2CO3 system

Reactivities of three metal oxides (Fe₂O₃, TiO₂ and MnO₂) with Na₂CO₃, and of their reaction products with CO₂, have been studied to enhance the O₂-releasing step in the two-step water splitting by the MnFe₂O₄–Na₂CO₃ system. X-ray diffraction analysis and thermogravimetric measurements showed that the reaction of α-Fe₂O₃ with Na₂CO₃ (mole ratio=1:1) completed within 10 min at 1073 K to produce NaFeO₂ (Fe₂O₃+Na₂CO₃→NaFeO₂+CO₂). Also, the regeneration of Fe₂O₃ and Na₂CO₃ proceeded readily by passing CO₂ gas through NaFeO₂ (71% yield). TiO₂ reacted with Na₂CO₃ (mole ratio=1:1) at 1073 K for 1 h to form Na₈Ti₅O₁₄ and Na₂TiO₃ (93% yield). However, in the reaction of the products with CO₂, the starting material (TiO₂) was not reproduced at the temperature range from 673 K to 1073 K, but Na₄Ti₅O₁₂ (having a lower Na content than the form Na₈Ti₅O₁₄) was formed. In the case of MnO₂ with Na₂CO₃ (mole ratio=2:1), Na_0.7MnO_2–2.05 and NaMnO₂ were produced at 1073 K for 1 h (80% yield), but the reaction between these products and CO₂ hardly proceeded.     

Effect of plastic deformation on ionic conduction in pure AgI and AgIAl2O3 composite solid electrolytes

The ionic conductivities of pure silver iodide and silver iodide-(10–40 mol%) alumina composites used as solid electrolytes are determined at room temperature by a.c. impedance spectroscopy as a function of compression pressure and annealing temperature. The ionic conductivities of both the pure and the composite silver iodide specimens increase with increasing compression pressure. This suggests that structural defects acting as conduction paths are generated in abundance by the plastic deformation. The mechanical strength of the as-deformed pure silver iodide specimen is decreased drastically by annealing at 413 K, whereas that of the as-deformed composite specimens remains virtually, unchanged. This indicates that the deformation-induced defects are present largely as dislocations. The ionic conductivity of the as-deformed pure silver iodide specimen determined during annealing at 323 K decreases with annealing time, whereas the conductivities of the as-deformed composite specimens are practically unchanged. It is concluded that the removal of the deformation-induced dislocations during annealing is impeded by dispersed alumina particles.     

The deactivation effect of Na2O and NaCl on CeO2–TiO2 catalysts for selective catalytic reduction of NO with NH3

The effect of Na₂O and NaCl on CeO₂–TiO₂ catalyst for the selective catalytic reduction of NO with NH₃ was investigated with BET, XRD, XPS, NH₃-TPD, H₂-TPR, in-situ DRIFT and catalytic activity measurements. The results showed that both Na species could deactivate the CeO₂–TiO₂ catalyst and Na₂O had a stronger effect than NaCl. The more serious deactivation by Na₂O could be ascribed to smaller surface area, fewer surface Ce³⁺ and chemical adsorbed oxygen, lower surface acidity, and worse reducibility. The introduction of NaCl and Na₂O facilitated the formation of new surface NO_x adspecies, but were inactive in NH₃-SCR reaction. The adsorption of NH₃ were inhibited. The NH₃-SCR reaction over the CeO₂–TiO₂ catalyst was governed by both E-R and L-H mechanisms. The introduction of NaCl and Na₂O didn't change the NH₃-SCR reaction mechanisms.     

A comparative study of Ni catalysts supported on Al2O3, MgO–CaO–Al2O3 and La2O3–Al2O3 for the dry reforming of ethane

CO₂ utilization through the activation of ethane, the second largest component of natural and shale gas, to produce syngas, has garnered significant attention in recent years. This work provides a comparative study of Ni catalysts supported on alumina, alumina modified with CaO and MgO, as well as alumina modified with La₂O₃ for the reaction of dry ethane reforming. The calcined, reduced and spent catalysts were characterized employing XRD, N₂ physisorption, H₂-TPR, CO₂-TPD, TEM, XPS and TPO. The modification of the alumina support with alkaline earth oxides (MgO and CaO) and lanthanide oxides (La₂O₃), as promoters, is found to improve the dispersion of Ni, enhance the catalyst's basicity and metal-support interaction, as well as influence the nature of carbon deposition. The Ni catalyst supported on modified alumina with La₂O₃ exhibits a relatively stable syngas yield during 8 h of operation, while H₂ and CO yields decrease substantially for Ni/Al₂O₃.     

The effect of CO2, CH4, H2O and N2 on MgNi alloys as hydrogen transporting media

Nickel-added magnesium hydrides have been thoroughly examined as H₂ transporting media. They have great advantages concerning H₂ content and storage cost. A serious disadvantage is their low packing density, so the container is inevitably bulky and heavy. To avoid this the transportation system could work simultaneously as a hydrogen purification system. To study the feasibility of such systems, the effects on the reaction of impurity gas both in the H₂ and adsorbed on the surface of powder particles have been examined experimentally.     

Effects of ion irradiation on H2O and CO2 absorption and desorption characteristics of Li2ZrO3 and Pt-coated Li2ZrO3

The effects of irradiation with 10 keV D₂⁺ ions on the hydrogen and water absorption and desorption characteristics of Li₂ZrO₃ and platinum-coated Li₂ZrO₃ (Pt-Li₂ZrO₃) were investigated by employing elastic recoil detection (ERD), weight gain measurement (WGM), and thermal desorption spectroscopy (TDS). WGM and ERD results indicated that the amounts of H and H₂O absorbed into the ion irradiated bulk Li₂ZrO₃ and Pt-Li₂ZrO₃ samples in air at room temperature increased up to ～2–3 times, as compared with those of the unirradiated ones. TDS examinations revealed that the amounts of hydrogen molecules (H₂) and H₂O released from the unirradiated Pt-Li₂ZrO₃ and ion irradiated Li₂ZrO₃ and Pt-Li₂ZrO₃ were approximately one order of magnitude higher than those of unirradiated Li₂ZrO₃. Li segregation, ion-induced oxygen deficiency, as well as Pt deposition significantly enhance the splitting of H₂O, eventually increasing the amounts of H accumulated in the bulk Li₂ZrO₃ and the H₂ release.     

Synthesis and characterization of nano-sized γ-Al2O3 for investigation the effect of temperature on catalytic dehydration of methanol to dimethyl ether

The new high surface area and high active nano-sized porous γ-Al₂O₃ catalyst was produced by a co-precipitation method. The synthesized catalyst was characterized by X-ray diffraction, Fourier transform infrared, NH₃-temperature programmed desorption, and Brunauer-Emmett-Teller techniques. The results of characterization tests showed excellent textural and acidic properties of the synthesized catalyst for the methanol dehydration reaction. Catalytic dehydration of methanol to dimethyl ether was performed in an adiabatic fixed bed reactor using the new nano-sized catalyst at different operating temperatures. The results showed that the highest methanol conversion occurs in the temperature range of 300–350°C. Finally, a new correlation was developed to predict methanol conversion from operating temperature.     

Preparation and characterization of α-Fe2O3 supported clay as a novel photocatalyst for hydrogen evolution

Improvement in the hydrogen evolution is reported over α-Fe₂O₃ supported on Algerian natural clay. The hetero-system is prepared by impregnation and calcination at 450 °C. It was characterized by X-ray diffraction, SEM analysis, FTIR spectroscopy and photo electrochemistry. The hematite Fe₂O₃ crystallizes in the corundum structure and exhibits n-type conductivity with a flat band potential of −0.88 V_SCE. Hence, the photo electrons located in Fe₂O₃-CB (−1 V_SCE) have high ability to reduce water into hydrogen. α-Fe₂O₃ gets effectively dispersed in the clay and the photoactivity increases with increasing its content. SO₃²⁻, working as hole scavenger, provides an absolute protection against the photo corrosion and favors the charges separation. The best performance of H₂ evolution occurs at alkaline pH on 10% Fe₂O₃/clay with a liberation rate 0.121 μmol/mg/min and a quantum efficiency of 1.2%.     

Studies on the LiMnO spinel system (obtained from melt-impregnation method) as positive electrodes for 4 V lithium batteries. Part III. Characterization of capacity and rechargeability

A series of ‘lithium-rich’ or ‘oxygen-rich’ spinel compounds are prepared from the reaction of LiNO₃ with electrochemically prepared manganese dioxide (EMD) via the melt-impregnation method. The capacity and rechargeability of these compounds are semi-quantitatively discussed in terms of an LiMn₂O₄Li₄Mn₅O₁₂Li₂Mn₄O₉ phase diagram. The capacity decreases as the lithium or oxygen content increases in the spinel matrix. By contrast, the rechargeability is improved.     

Thermodynamic and kinetic studies of NaBH4 regeneration by NaBO2–Mg–H2 ternary system at isothermal condition

NaBH₄ is a candidate for H₂ storage in solid phase. NaBH₄ hydrolysis readily produces H₂ gas and NaBO₂ which can regenerate NaBH₄ with pressurized hydrogen and the aid of a reducing agent like Magnesium above 500 °C. This paper deals with the NaBH₄ thermochemical regeneration from the NaBO₂–Mg–H₂ ternary system at isothermal temperatures between 558 and 634 °C and H₂ pressure in the range 2–31 bar. A simplified Langmuir adsorption model has been applied for the interpretation of the in-situ H₂ pressure variations. The applied model is zero-dimensional but provides a reasonable approach to identify the rate determining step and acquire relevant thermodynamic and kinetic parameters such as equilibrium constant (K_eq), Gibbs free energy (Δ_rG⁰) and reaction rate coefficients (k). The study provides an apparent activation energy and Gibbs free energy of this process of 29.2 kJ/mol and −76.9 kJ/mol, respectively.     

Amino acid assisted-synthesis and characterization of magnetically retrievable ZnCo2O4–Co3O4 nanostructures as high activity visible-light-driven photocatalyst

A novel and environment-friendly way to fabricate ZnCo₂O₄–Co₃O₄ nanostructures (ZC–C NSs) as highly efficacious visible light photocatalyst was developed with the aid of the amino acids as new kinds of fuel and stabilizers, for the first time. Role of the efficacious parameters like kind of amino acid and its amount on the morphological characteristics and performance of ZC–C NSs as visible light photocatalyst was explored. The outcomes demonstrated that alteration in the kind of amino acid and its amount could be beneficial and determinative for control over dimension, performance and shape of ZC–C. Characteristics of as-produced ZC–C NSs were explored with the variant techniques. The estimated band gap demonstrates that ZC–C NSs are able to be activated by employing visible light for decomposition of contaminants. The performance of as-produced ZC–C NSs with variant morphologies were estimated from the destruction of organic contaminant, acid blue 92, illuminated with the aid of visible light. This is the first endeavor on the examination of efficiency of ZnCo₂O₄–Co₃O₄ nanostructures (produced with the aid of the various amino acids) as visible light photocatalyst for destruction of acid blue 92. The outcomes illustrate that ZC–C NSs produced with the aid of Phenylalanine are able to manifest superior performance to degrade the organic contaminant, acid blue 92. Besides, usage of new kind of fuel and stabilizing agent (amino acid) may be leading to fabricate ZC–C NSs, which are efficiently able to remove the undesirable contaminant, and eventuating to diminution in the environmental pollution.     

Thermal decomposition synthesis,characterization and electrochemical hydrogen storage characteristics of Co3O4–CeO2 porous nanocomposite

Particle-like Co₃O₄–CeO₂ nanocomposite was synthesized via a facile thermal decomposition process in the presence of fructose as a green capping agent and ammonium cerium(IV) nitrate as Ce source. The effect of various parameters such as different cobalt sources, calcination temperature and time were investigated on the size and morphology of products. The transmission electron microscopy observations indicated that the synthesized products have a particle-like shape with an average diameter of 18–35 nm. For the first time, the electrochemical hydrogen storage performance of Co₃O₄–CeO₂ porous nanocomposite was investigated via chronopotentiometry method in aqueous KOH solution in this paper. The electrochemical measurements showed that this product has a good hydrogen storage capacity at room temperature. Its maximum discharge capacity was 5200 mAh/g after 20 cycles. Therefore, Co₃O₄–CeO₂ porous nanocomposite showed that it is a good candidate for electrochemical hydrogen storage.     

Effects of NH＿3 on N＿2O Formation and Destruction in Fluidized Bed Coal Combustion

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