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1.
The intercalation of cations into layered-structure electrode materials has long been studied in depth for energy storage applications. In particular, Li +-, Na +-, and K +-based cation transport in energy storage devices such as batteries and electrochemical capacitors is closely related to the capacitance behavior. We have exploited different sizes of cations from aqueous salt electrolytes intercalating into a layered Nb 2CT x electrode in a supercapacitor for the first time. As a result, we have demonstrated that capacitive performance was dependent on cation intercalation behavior. The interlayer spacing expansion of the electrode material can be observed in Li 2SO 4, Na 2SO 4, and K 2SO 4 electrolytes with d-spacing. Additionally, our results showed that the Nb 2CT x electrode exhibited higher electrochemical performance in the presence of Li 2SO 4 than in that of Na 2SO 4 and K 2SO 4. This is partly because the smaller-sized Li + transports quickly and intercalates between the layers of Nb 2CT x easily. Poor ion transport in the Na 2SO 4 electrolyte limited the electrode capacitance and presented the lowest electrochemical performance, although the cation radius follows Li +>Na +>K +. Our experimental studies provide direct evidence for the intercalation mechanism of Li +, Na +, and K + on the 2D layered Nb 2CT x electrode, which provides a new path for exploring the relationship between intercalated cations and other MXene electrodes. 相似文献
2.
It is established that the reaction of recharging trioxalate complexes of ruthenium(III) occurs in the case of solutions with excess supporting oxalate salts of alkali metals K +, Na +, and Cs + in reversible conditions, and limiting recharge currents are caused by diffusion. At the same time, values of diffusion coefficients for complex anion [Ru(C 2O 4) 3] –3 decrease by almost two times upon going from potassium to sodium and cesium electrolytes. Substantial differences in the limiting currents in solutions containing excess amounts of the above salts are explained by the formation, at least in the case of cesium and sodium electrolytes, of ionic associates whose reduction rate at a fixed potential is lower than that of nonassociated anion [Ru(C 2O 4) 3] –3. With solution dilution by supporting salts, transition is observed from reversible recharge conditions to absolutely irreversible conditions and a change in the above sequence of the effect of supporting cations on the recharge rate; at a fixed potential, the process decelerates in the series Cs + > K + > Na +. The reduction wave of the ruthenium(II) oxalate complexes in solutions with excess supporting electrolyte happens to depend on pH and, probably, is determined by simultaneous formation of adsorbed atoms of hydrogen (or ruthenium hydride) on atoms of ruthenium(0). 相似文献
3.
The electrochemical performances of activated carbon (AC) in 0.5 mol/l Li 2SO 4, Na 2SO 4 and K 2SO 4 aqueous electrolytes were investigated. The cyclic voltammetric results at different scan rates show that the rate behaviors of AC in the three electrolytes improve in the order of Li 2SO 4 < Na 2SO 4 < K 2SO 4. This improvement can be mainly ascribed to the following two reasons: (1) the decreasing equivalent series resistance in the order of Li 2SO 4 > Na 2SO 4 > K 2SO 4, which is the main factor influencing the maximum output power, and (2) the increasing migration speed of hydrated ions in the bulk electrolyte and in the inner pores of AC electrode in the order of Li + < Na + < K +. Their cycling behaviors do not show any differences in capacitive fading. The above results provide valuable information to explore new hybrid supercapacitors. 相似文献
4.
The solid‐liquid equilibria in the quinary system Na +, K +//Cl ?, SO 2?4, B 4O 2?7‐H 2O at 298 K had been studied experimentally using the method of isothermal solution saturation. Solubilities and densities of the solution of the quinary system were measured experimentally. Based on the experimental data, the dry‐salt phase diagram and water content diagram of the quinary system were constructed, respectively. In the equilibrium diagram of the quinary system Na +, K +//Cl ?, SO 2?4, B 4O 2?7‐H 2O at 298 K, there are five invariant points F1, F2, F3, F4 and F5; eleven univariant curves E1F1, E2F2, E3F3, E4F5, E5F2, E6F4, E7F5, F1F4, F2F4 F1F3 and F3F5, and seven fields of crystallization saturated with Na 2B 4O 7 corresponding to Na 2SO 4, Na 2SO 4·10H 2O, Na 2SO 4·3K 2SO 4 (Gla), K 2SO 4, K 2B 4O 7·4H 2O, NaCl and KCl. The experimental results show that Na 2SO 4·3K 2SO 4 (Gla), K 2SO 4 and K 2B 4O 7·4H 2O have bigger crystallization fields than other salts in the quinary system Na +, K +//Cl ?, SO 2?4, B 4O 2?7‐H 2O at 298 K. 相似文献
5.
在Tl 2SO 4+Na 2SO 4+二(2-乙基己基)二硫代磷酸+n-C 8H 18+水体系中, 测定了0.1-2.0 mol•kg -1离子强度范围内Tl + 的平衡摩尔浓度。水相中电解质Na 2SO 4 控制溶液离子强度, 有机相中萃取剂取278.15 K至303.15 K范围内的恒定摩尔浓度。通过外推法和多项式近似得到了不同温度下的标准萃取常数K 0,计算了萃取过程的热动力学量。 相似文献
6.
The equilibrium molalities In 3+ in {In 2(SO 4) 3 + Na 2SO 4 + HDEHMTPCA + n-C 8H 18 + water} were measured at ionic strength from (0.1 to 2.0) mol · kg −1 containing Na 2SO 4 as supporting electrolyte in aqueous phase and at constant molality extractant at temperatures from (278.15 to 303.15) K in organic phase. The standard extraction constants K0 at various temperatures were obtained by methods of extrapolation and polynomial approximation. Thermodynamic quantities for the extraction process were calculated. 相似文献
7.
A strategy is described to increase charge storage in a dual electrolyte Na‐ion battery (DESIB) by combining the redox chemistry of the electrolyte with a Na + ion de‐insertion/insertion cathode. Conventional electrolytes do not contribute to charge storage in battery systems, but redox‐active electrolytes augment this property via charge transfer reactions at the electrode–electrolyte interface. The capacity of the cathode combined with that provided by the electrolyte redox reaction thus increases overall charge storage. An aqueous sodium hexacyanoferrate (Na 4Fe(CN) 6) solution is employed as the redox‐active electrolyte (Na‐FC) and sodium nickel Prussian blue (Na x‐NiBP) as the Na + ion insertion/de‐insertion cathode. The capacity of DESIB with Na‐FC electrolyte is twice that of a battery using a conventional (Na 2SO 4) electrolyte. The use of redox‐active electrolytes in batteries of any kind is an efficient and scalable approach to develop advanced high‐energy‐density storage systems. 相似文献
8.
The enthalpy changes of salting process of hen-egg
white lysozyme in buffer acetate solutions (pH=4.25) as a function of concentration
of following electrolytes: LiCl, KCl, K 2SO 4,
Li 2 SO 4 and (NH 4) 2SO 4
are determined. Obtained data according to McMillan and Mayer’s approach,
has been analyzed in the terms of the enthalpic pairwise interaction coefficients:
lysozyme – lysozyme hxx,
and lysozyme – salt hxy.
The ability of cations to precipitate lysozyme solution in relation to the
concentration of cations can be seen from the series as follows: Li +>
Na +>K +>NH 4+ + 相似文献
9.
The equilibrium molalities Tl + were measured in {Tl 2SO 4 + Na 2SO 4 + D 2EHPA + n-C 8H 18 + Water} system at ionic strength from 0.1 to 2.0 mol kg ?1 containing Na 2SO 4 as supporting electrolyte in aqueous phase and at constant molality extractant at temperatures from 278.15 K to 303.15 K in organic phase. The standard extraction constants K 0 at various temperatures were obtained by methods of extrapolation and polynomial approximation. Thermodynamic quantities for the extraction process were calculated. 相似文献
10.
A comprehensive thermodynamic model based on the electrolyte NRTL (eNRTL) activity coefficient equation is developed for the NaCl + H 2O binary, the Na 2SO 4 + H 2O binary and the NaCl + Na 2SO 4 + H 2O ternary. The NRTL binary parameters for pairs H 2O-(Na +, Cl −) and H 2O-(Na +, SO 42−), and the aqueous phase infinite dilution heat capacity parameters for ions Cl − and SO 42− are regressed from fitting experimental data on mean ionic activity coefficient, heat capacity, liquid enthalpy and dissolution enthalpy for the NaCl + H 2O binary and the Na 2SO 4 + H 2O binary with electrolyte concentrations up to saturation and temperature up to 473.15 K. The Gibbs energy of formation, enthalpy of formation and heat capacity parameters for solids NaCl (s), NaCl·2H 2O (s), Na 2SO 4(s) and Na 2SO 4·10H 2O (s) are obtained by fitting experimental data on solubilities of NaCl and Na 2SO 4 in water. The NRTL binary parameters for the (Na +, Cl −)-(Na +, SO 42−) pair are regressed from fitting experimental data on dissolution enthalpies and solubilities for the NaCl + Na 2SO 4 + H 2O ternary. 相似文献
11.
This paper reports on the effects of the K 2SO 4, H 2SO 4, NaCl, HCl, and tetrabutylammonium bromide concentrations (0.01–0.0002 M) and the presence of formic, acetic, and butyric
acids in the electrolyte on the kinetic characteristics of oxygen reduction to H 2O 2 in a carbon black gas-diffusion electrode (GDE) and on the H 2O 2 accumulation kinetics in electrolyte at current densities of 30–100 mA/cm 2. The introduction of K 2SO 4 and tetrabutylammonium bromide in the electrolyte led to an increase in the transfer coefficient α and a decrease in the
coefficients in the Tafel equation. The concentration and the current efficiency of H 2O 2 decreased with the salt to acid concentration ratio. The organic acids reduced the current efficiency of H 2O 2 and increased the electrode polarization. Peracids with a current efficiency of up to 0.27% and concentration of up to 7.5
mM were obtained. Solutions of H 2O 2 with concentrations of 0.6–3.3 M and current efficiencies of 17–75% were obtained at current densities of 30–100 mA/cm 2 in electrolytes with salt and inorganic acid concentrations of 0.9–40 g/l and in the presence of organic acids. 相似文献
12.
The kinetics of the redox reaction between mandelic acid (MA) and ceric sulfate have been studied in aqueous sulfuric acid solutions and in H 2SO 4? MClO 4 (M + = H +, Li +, Na +) and H 2SO 4? MHSO 4 (M + = Li +, Na +, K +) mixtures under various experimental conditions of total electrolyte concentration (that is, ionic strength) and temperature. The oxidation reaction has been found to occur via two paths according to the following rate law: rate = k[MA] [Ce(IV)], where k = k1 + k2/(1 + a) 2[HSO 4?] 2 = k1 + k2/(1 + 1/a) 2[SO 42?] 2, a being a constant. The cations considered exhibit negative specific effects upon the overall oxidation rate following the order H + ? Li + < Na + < K +. The observed negative cation effects on the rate constant k1 are in the order Na + < Li + < H +, whereas the order is in reverse for k2, namely, H + ? Li + < Na +. Lithium and hydrogen ions exhibit similar medium effects only when relatively small amounts of electrolytes are replaced. The type of the cation used does not affect significantly the activation parameters. 相似文献
13.
Performance of dye-sensitized nano-crystalline TiO2 thin film-based photo-electrochemical solar cells (PECSCs) containing gel polymer electrolytes is largely governed by the nature of the cation in the electrolyte. Dependence of the photovoltaic performance in these quasi-solid state PECSCs on the alkaline cation size has already been investigated for single cation iodide salt-based electrolytes. The present study reports the ionic conductivity dependence on the nature of alkaline cations (counterion) in a gel polymer electrolyte based on binary iodides. Polyacrylonitrile-based gel polymer electrolyte series containing binary iodide salts is prepared using one of the alkaline iodides (LiI, NaI, KI, RbI, and CsI) and tetrapropylammonium iodide (Pr4NI). All the electrolytes based on binary salts have shown conductivity enhancement compared to their single cation counterparts. When combined with Pr4NI, each of the Li+, Na+, K+, Rb+, and Cs+ cation containing iodide salts incorporated in the gel electrolytes has shown a room temperature conductivity enhancement of 85.59, 12.03, 12.71, 20.77, and 15.36%, respectively. The conductivities of gel electrolytes containing binary iodide systems with Pr4NI and KI/RbI/CsI are higher and have shown values of 3.28, 3.43, and 3.23 mS cm−1, respectively at room temperature. The influence of the nature of counterions on the performance of quasi-solid state dye-sensitized solar cells is investigated by assembling two series of cells. All the binary cationic solar cells have shown more or less enhancements of open circuit voltage, short circuit current density, fill factor, and efficiency compared to their single cation counterparts. This work highlights the importance of employing binary cations (a large and a small) in electrolytes intended for quasi-solid state solar cells. The percentage of energy conversion efficiency enhancement shown for the PECSCs made with electrolytes containing Pr4NI along with Li+, Na+, K+, Rb+, and Cs+ iodides is 260.27, 133.65, 65.27, 25.32, and 8.36%, respectively. The highest efficiency of 4.93% is shown by the solar cell containing KI and Pr4NI. However, the highest enhancements of ionic conductivity as well as the energy conversion efficiency were exhibited by the PECSC made with Li+-containing binary cationic electrolyte. 相似文献
14.
A complete, critical evaluation of all phase diagram and thermodynamic data was performed for all phases of the (Na 2SO 4 + K 2SO 4 + Na 2S 2O 7 + K 2S 2O 7) system and optimized model parameters were obtained. The Modified Quasichemical Model in the Quadruplet Approximation was used for modelling the liquid phase. The model evaluates first- and second-nearest-neighbour short-range ordering, where the cations (Na + and K +) are assumed to mix on a cationic sublattice, while anions were assumed to mix on an anionic sublattice. The Compound Energy Formalism was used for modelling the solid solutions of (Na,K) 2SO 4 and (Na,K) 2S 2O 7. The models can be used to predict the thermodynamic properties and phase equilibria in multicomponent heterogeneous systems. The experimental data from the literature were reproduced within experimental error limits. 相似文献
15.
The kinetics of the cerium(IV) oxidation of p-nitro and p-methoxymandelic acids have been investigated in H 2SO 4-MHSO 4 (M + = Li +, Na +, K +) and H 2SO 4-MClO 4 (M + = H +, Na +) mixtures at a constant total electrolyte concentration of 2.00 mol/dm 3. The oxidation of p+nitromandelic acid proceeds through two [H +]-independent paths, as was also observed for some substituted mandelic acids studied previously. The kinetic behavior of the p-methoxy derivative differs from that of the other mandelic acids in that (1) the oxidation occurs via two [H +]-dependent paths, (2) the reaction rate is anomalously high, (3) the activation enthalpy and entropy of the overall process are markedly lower. It provides strong support to the suggestion that a different mechanism is operative. The substituent effects and the reaction mechanism are discussed. 相似文献
16.
An electrochemical cell of potentiometric type Na 0.5WO 3 (reference electrode)/Na +-solid electrolyte/PbS (working electrode) capable of rapid and selective changing of the electromotive force value owing
to H 2S concentration variations in gas surroundings has been investigated at 295±1 K and a relative humidity of 52%. The sensitivity
of this cell was 130 mV/decade at a H 2S concentration within the range 13–130 ppm. Sodium-conducting solid electrolytes of Na 3Zr 2Si 2PO 12 and Na 5GdSi 4O 12 compositions were used as the Na + solid electrolyte. Such a cell can be used for analysis of H 2S containing water solutions when the reference electrode and the Na + solid electrolyte are thoroughly isolated from the surroundings.
Electronic Publication 相似文献
17.
The adsorption of lignosulphonate on polystyrene latex particles was investigated as a function of SO 4 2? content and molecular weight distribution of the polyelectrolyte chain. The results showed an increase in adsorption with increase of SO 4 2? content. This was attributed to the screening of Coulombic repulsion between adjacent sulphonate groups in the chain which in the presence of sufficient electrolyte may behave as a nonionic polymer adopting a loop-train conformation. The adsorption also increased with increase of the proportion of the high molecular weight fraction, in the sample. Electrophoretic mobility measurements showed a complex behaviour depending on SO 4 2? content and molecular weight of the chain. It is likely that the shift in shear plane as the conformation of the chain changes (as a result of addition of electrolyte or increase in molecular weight) may play a dominant role. Critical flocculation concentration measurements using the electrolytes KCl, Na 2SO 4 and CaCl 2 demonstrated the contribution of “steric repulsion” in determining the stability as well as the specific role of Ca 2+. Finally, viscosity-volume fraction curves showed the dependence of interaction in a concentrated system on the SO 4 2? content. 相似文献
18.
以TiO 2/Ti为阳极, Ti网为阴极, 研究了活性艳红K-2BP在NaCl和Na 2SO 4电解质中的降解情况, 深入探讨了两种电解质在光电催化降解染料中的作用, 研究了电解质浓度、溶液pH值的影响, 并讨论了在混合盐电解质存在下, 活性艳红K-2BP的降解行为. 研究表明, 以NaCl为电解质时, Cl -会转化为氧化性很强的活性氯, 活性氯及光电的共同作用, 加速了染料的降解. 以Na 2SO 4为电解质时, SO 42-在光电的作用下将发生两类反应, 一部分SO 42-捕获光生空穴和HO•, 对光电催化降解染料起抑制作用; 另一部分SO 42-将发生反应生成H 2O 2, 对染料降解起促进作用.
关键词 光电催化; 活性艳红K-2BP; TiO 2/Ti电极; 电解质 相似文献
19.
The nature of active centers and anionic mechanism of the styrene polymerization during the 9,10-antraquinone electroreduction in the monomer-dimethylacetamide-alkali metal (or ammonium) perchlorate system is studied by voltammetry, ESR, IR- and UV-spectroscopy. It is shown that the potential of electrolysis depends on the supporting electrolyte composition; the association of the supporting electrolyte cation with the organic anion, in turn, affects the mechanism of the polymerization initiation and the macromolecule growth kinetics. The potential of generation of 9,10-antraquinone and the styrene conversion in catholyte increase with increasing radius of the supporting cation in the series Li + <; Na + <; K + <; Rb + <; Cs + <; (C 2H 5) 4N + <; (C 4H 9) 4N +. 相似文献
20.
Series of maleate monoester and diester monomers based on poly(ethylene glycol) monomethyl ether (MPEG) were copolymerized using the ionizable 2‐acrylamido‐2–methyl propane sulfonic acid (AMPS) via different dose rate of electron‐beam irradiation (40–150 kGy). The crosslinking of the copolymers were carried out in aqueous acidic solutions at pH 1 or in the presence of 1% N,N‐methylene bisacrylamide (MBA) as crosslinking agent. The final equilibrium water content and swelling capacities for the prepared hydrogels were determined in aqueous solutions at pH 1, 6.8, and 12 and in aqueous salt solutions at 298 K. Swelling equilibria for prepared hydrogels were determined in different molar salt solutions of NaCl, KCl, CaCl 2, Na 2SO 4, K 2SO 4, and CaSO 4. The swelling ratios of gels in pure water and in the salt solutions were found to depend on the counterion species in the increasing sequence of Ca 2+, Na + and K +. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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