NaClO4 Aqueous Solution Research Articles

Tuning the capacitance properties of MnCO3 by choice of the electrolyte

Modifying electrolytes is an effective way of improving the capacitance properties. However, this strategy is not explored much compared to tuning the physicochemical properties of the electrode material. Herein, the capacitance properties of electrodeposited MnCO3 (E-MnCO3) are improved by the choice of aqueous electrolyte. MnCO3 is electrodeposited on stainless steel foil and characterized by XRD, Raman spectroscopy and SEM. The capacitance properties of E-MnCO3 are studied in aqueous solutions of NaClO4, Mg(ClO4)2 and La(ClO4)3. Owing to higher ionic conductivity, lower solution and charger transfer resistance, and an increase in the number of electrochemical active sites per cation adsorption/intercalation, E-MnCO3 delivers higher specific capacitance and better rate capability in La(ClO4)3 than in other electrolytes. The capacitance properties of E-MnCO3 in various electrolyte follow the order: La(ClO4)3 > Mg(ClO4)2 > NaClO4.

Carbon‐Coated NaVPO4F as a High‐Capacity Cathode for Aqueous Sodium‐Ion Battery

AbstractNaVPO4F has garnered significant attention as a promising cathode material for non‐aqueous sodium‐ion batteries due to its high theoretical specific capacity and appropriate potential. However, the dissolution of vanadium component of NaVPO4F in aqueous electrolytes has restricted its application in aqueous sodium‐ion batteries (ASIBs). Herein, we report the use of carbon‐coated NaVPO4F as a cathode material in ASIBs. This cathode material exhibited a discharge capacity of 111 mAh g−1 at 0.5 A g−1 in a concentrated 17 m NaClO4 aqueous solution and demonstrated capacity retention of 74.4 % over 100 cycles. The experimental results confirmed that the carbon coating on NaVPO4F and high‐concentration NaClO4 aqueous electrolyte exhibited positive effects in restraining vanadium dissolution. Additionally, when configuration with NaTi2(PO4)3@C as anode, the full cell exhibited a capacity of 43.9 mAh g−1 with an average operating voltage of 1.2 V at a current density of 0.5 A g−1 in a concentrated 17 m NaClO4 aqueous electrolyte. These outcomes underscore the potential of NaVPO4F@C as a promising cathode material for ASIBs.

Synthesis and Application of an Aromatic Sulfonate Sodium Salt for Aqueous Sodium‐Ion Battery Electrolytes

The two‐step synthesis of sodium (2,3,5,6‐tetrafluorophenoxy) diethane sulfonate (Na‐TFP) is reported, starting from 2,3,5,6‐tetrafluorohydroquinone as the precursor. Compared with conventional aqueous electrolytes such as 0.5 m NaClO4 and Na2SO4, the 0.5 m aqueous solution of Na‐TFP provides higher ionic conductivity over a wide range of temperature (e.g., >60 mS cm−1 at 20 °C and >70 mS cm−1 at 30 °C) and a wider electrochemical stability window. Electrochemical cells with Na2VTi(PO4)3 as the positive electrode active material and a carbon‐based negative electrode provide a stable capacity for more than 450 cycles in 0.5 m Na‐TFP. Additionally, symmetric cells with Na2VTi(PO4)3 as the active material for the negative and positive electrode are studied. The cells employing 0.5 m Na‐TFP exhibit a good cycling stability at a high dis‐/charge rate of 5C for more than 50 cycles, which is superior to the performance of the cells employing 0.5 m aqueous solutions of NaClO4 and Na2SO4 as the electrolyte. The design of this bifunctional salt may trigger new ideas for the development of water‐based sodium‐ion battery electrolytes.

Effect of conductivity, viscosity, and density of water-in-salt electrolytes on the electrochemical behavior of supercapacitors: molecular dynamics simulations and in situ characterization studies

Molecular configurations of the 1.0 mol dm−3 and 8.0 mol dm−3 NaClO4 aqueous electrolytes, and shear viscosity and ionic conductivity as a function of the molar and molal concentrations of NaClO4 aqueous solutions.

Temperature-Induced Change of Water Structure in Aqueous Solutions of Some Kosmotropic and Chaotropic Salts.

The hydrogen bond structure of water was examined by comparing the temperature dependent OH-stretching bands of water and aqueous NaClO4, KClO4, Na2SO4, and K2SO4 solutions. Results called attention to the role of cations on top of the importance of anions determining the emerging structure of a multi-layered system consisting single water rings or multi-ring water-clusters.

Investigation of electrolysis-related modification of graphene films in biosensors

In this work, the modification of the surface parameters of graphene chips after electrolysis treatment in a NaClO4 aqueous solution has been studied. Two electrolysis modes have been analysed. In the first one, a negative potential (-0.2 V) is applied to the graphene chips, while in the second one the potential is positive (0.8 V). Investigation using a number of techniques including atomic force microscopy, Kelvin probe force microscopy, Raman spectroscopy, measurements of current-voltage characteristics and low-frequency noise has shown that the electrolysis mode with application of a positive potential on graphene chips decreases the 1/f noise and allows one to obtain a uniform surface potential distribution while leaving the graphene structure undamaged. The results of this study help to understand the efficiency and reproducibility of the procedure for electrolysis treatment of graphene chips.

PH Overpotential for Unveiling the pH Gradient Effect of H + /OH − Transport in Electrode Reaction Kinetics

pH Overpotential for Unveiling the pH Gradient Effect of H ⁺ /OH ⁻ Transport in Electrode Reaction Kinetics

Effect of the Supporting Electrolyte on Chloroform Reduction at a Silver Electrode in Aqueous Solutions.

Herein, we report, for the first time, a comparative study on the electrocatalytic reduction of chloroform on silver in different aqueous supporting electrolytes. Cyclic voltammetry measurements were performed at a wide range of scan rates and concentrations of CHCl3 using 0.05 M NaClO4, NaH2PO4, and Na2HPO4 as supporting electrolytes. We observed that a type of supporting electrolyte anion strongly influences both the potential as well as the current density of the chloroform reduction peak, mainly due to the presence of OH− in an alkaline Na2HPO4 solution, which is a specifically interacting anion. Moreover, the highest sensitivity of the Ag electrode toward CHCl3 reduction was observed in a neutral NaClO4 aqueous solution. It was found that the electroreduction of chloroform at the silver surface occurs via a concerted mechanism regardless of the type of the studied supporting electrolyte.

Synthesis and the Cathode Properties of Na3Fe3(PO4)4 for Sodium-Ion Battery

Na-ion batteries (NiBs) are very attractive and promising for large scale electric power storage system because of the abundance for sodium source, the high cost-effectiveness and the long lifetime. Among the candidate of cathode active materials for NiBs, practical use of iron phosphate such as NaFePO4, Na2FePO4F, and Na3Fe3(PO4)4 [1] or carbonophosphate such as Na3FePO4CO3 [2] is expected from the viewpoint of cost and safety. In order to make full use of the resource and cost advantages of these materials, the raw materials used in the synthesis and the synthesis method are also important. In this presentation, we report the direct synthesis of Na3Fe3(PO4)4 by the hydrothermal method with mass productivity and the cathode properties. Synthesis was carried out using ferrous sulfate hydrate (FeSO4·nH2O), phosphoric acid, and various sodium phosphate salts as sodium sources with various the raw material composition, hydrothermal treatment temperature, and reaction time. For the purpose of controlling the reaction, synthesis was performed under the condition that an oxidizing agent or a reducing agent was added. The obtained compounds were identified by powder X-ray diffraction measurement and Rietveld analysis. Iron (Ⅱ) sulfate (FeSO4·7H2O), phosphoric acid (H3PO4), sodium dihydrogen phosphate (NaH2PO4·2H2O) and sodium persulfate (Na2S2O8) were used as raw materials, and hydrothermal synthesis was performed at 200 ° C for 16 hours. From the Rietveld analysis, the obtained compound was assigned to the layered structure Na3Fe3(PO4)4. This hydrothermal synthesis Na3Fe3(PO4)4 delivered initial discharge capacity of 160mAh g-1 between -1.2 and 1.3 V with a reference electrode of Ag/AgCl at 2 mA cm-2 in the 17 m NaClO4 aqueous solution (Figure 1). In the presentation, we will be reported the details of cathode properties of Na3Fe3(PO4)4.

Synthesis, structure and fluxionality of Co(III) complexes containing chelated sulfate

The syntheses and characterisation of the complexes [Co(pmea)(O2SO2)]ClO4 and [Co(pmap)(O2SO2)]ClO4 (pmea = bis((2-pyridyl)methyl)-2-((2-pyridyl)ethyl)amine; pmap = bis(2-(2-pyridyl)ethyl)(2-pyridylmethyl)amine), containing chelating sulfato ligands, are reported. These were prepared by oxidation of a solution containing CoSO4·7H2O and the tripodal tetraamine ligand with either (NH4)2[Ce(O2NO)6] (pmea) or Oxone (2KHSO5·KHSO4·K2SO4; pmap), and their structures were confirmed by X-ray crystallography. [Co(pmap)(O2SO2)]ClO4 crystallised as the 6-isomer from aqueous NaClO4 solution, while [Co(pmea)(O2SO2)]ClO4 was obtained as a mixture of the 5- and 6-isomers, with both isomers being able to be resolved in the X-ray structure. Comparison of the IR spectra of [Co(pmap)(O2SO2]ClO4 and [Co(pmap)(O2CO)]ClO4 allowed assignment of IR bands due to the chelated sulfato ligand. Fluxionality in [Co(pmea)(O2SO2)]ClO4 was resolved using 1H VT-NMR, and was found to result from ‘flapping’ of the pyridylethyl arm of the pmea ligand between two possible conformations.

Some Observations on the Electrochemical Reactions of Bisphenol A on Polycrystalline Gold in Contact with 0.1 M Aqueous NaClO4 Solution

Experimental results are presented on the electrochemical behavior of BPA at a gold | 0.1 M sodium perchlorate electrode. During the cycling of the electrode potential an adherent thin polymer layer was formed on the electrode. The film buildup process was followed in situ with an electrochemical quartz crystal microbalance (EQCM) and ex situ by electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) was used for the study of the structure/morphology of the deposited polymer coating. The results imply that polymerization and degradation of the BPA monomer may occur simultaneously during its electrochemical oxidation.

EQCM Studies on the Effect of Anti-freezing Additives on the Storage Behavior of Ions at Activated Carbon Electrodes in NaClO4 Aqueous Solutions†

Electrochemical quartz crystal microbalance(eqcm) was used to investigate the adsorption of na+ into the micropores of activated carbon in 5 mol/l naclo4 +x mol/l meoh and 5 mol/l naclo4 +x mol/l etoh aqueous solutions. molecule numbers of methanol or ethanol associated with each na+ at the interfaces were estimated. the results show that methanol and ethanol are adsorbed into the micropores together with na+ the higher the concentration of methanol and ethanol in bulk solutions was, the more molecule numbers of methanol or ethanol associated with each na+ adsorpted into the pores of activated carbon; methanol and ethanol adsorpted into the pores occupied some space of the micropores and lowered the dielectric constant of the double layers, thus suppressed the specific capacitance of maxsorb negative electrodes.

Tunable Ag Micromorphologies Show High Activities for Electrochemical H2 Evolution and CO2 Electrochemical Reduction

Contaminate-free nanostructured Ag is prepared from electrochemical redox-treated Ag by two different potential pulses (DP and r-DP) in an NaBr aqueous solution. Agr-DP and AgDP from r-DP and DP, respectively, are easily tuned for their activities in the hydrogen evolution reaction (HER) favoring or selective CO2 reduction reaction (CO2RR). Agr-DP shows Pt-like HER activity in H2SO4 aqueous solution, and AgDP is capable of electrochemically reducing CO2 to CO with approximately 97.8% catalytic selectivity at a low overpotential of ∼0.25 V in NaHCO3 aqueous solution. The electrochemical signals for the first observed CO2•– intermediate adsorption (CO2ads•–) and HCO3– adsorption (HCO3–ads) in the selected NaClO4 aqueous solution were used to understand the possible role of HCO3– in CO2RR.

Crossing VIMP and EIS for studying heterogeneous sets of copper/bronze coins

Electrochemical impedance spectroscopy (EIS) and voltammetry of immobilized particles (VIMP) measurements using air-saturated mineral water and 0.10 M NaClO4 aqueous solution as electrolytes were applied to eurocent coins and a set of copper/bronze coins from the late nineteenth century exhibiting significant heterogeneity in their degree and type of corrosion. The obtained data presented satisfactory repeatability being fitted to relatively simple equivalent circuits which were dependent on the electrolyte and bias potential, the more satisfactory conditions being obtained using the reduction of dissolved oxygen as a redox probe. Consistent data were obtained using VIMP and EIS characterizing different corrosion patterns, and establishing the possibility of discriminating different monetary emissions in favorable cases of high level of corrosion.

Proton-Rocking-Chair-Type Redox Capacitors Based on Indium Tin Oxide Electrodes with Multilayer Films Containing Ru Complexes.

A rechargeable proton-rocking-chair-type redox capacitor was fabricated using scalable layer-by-layer-(LbL)-assembled films composed of two dinuclear Ru complexes that exhibit proton-coupled electron-transfer (PCET) reactions with different Ru(II/III) redox potentials (RuNH-OH and RuCH-OH). RuNH-OH and RuCH-OH contain different coordination environments that involve two phosphonate linker ligands at both ends and bridging 2,6,2',6'-tetrakis(benzimidazol-2-yl)-4,4'-bipyridine or 1,3,1',3'-tetrakis(benzimidazol-2-yl)-5,5'-biphenyl ligands, respectively. The molecular units were assembled onto indium tin oxide (ITO) electrodes by complexation between the phosphonate groups and zirconium(IV) ions. The LbL growing process of these multilayer films was monitored by electrochemical or UV-vis spectroscopic measurements. The thus obtained LbL films on the ITO electrodes showed PCET reactions at different potentials, depending on the bridging ligands. The introduction of cyclometalated Ru-C bonds in the bridging ligand of RuCH-OH led to the stabilization of the ruthenium(III) oxidation state, and therefore, RuCH-OH exhibited lower p Ka values for the imino N-H protons in the bridging benzimidazole groups compared to those of the corresponding RuNH-OH complex. The proton movements that accompany the redox reaction in the Ru multilayer films on the ITO electrode were confirmed using a pH indicator probe. For the performance test of a proton-rocking-chair-type redox capacitor, a two-electrode system composed of RuNH-OH and RuCH-OH multilayer films on ITO electrodes was examined in an aqueous solution of NaClO4. Under galvanostatic conditions, stable, reversible, and repeatable charging/discharging processes occurred. The capacitance increased with an increasing number of LbL layers. For comparison, a similar redox capacitor composed of two RuNMe-OH and RuCMe-OH analogues, in which all four imino N-H protons on the benzimidazole moieties are protected by N-Me groups, was constructed and examined. In these complexes, the capacitance decreased by 77% compared to the PCET-type capacitor composed of a cell containing RuNH-OH and RuCH-OH; this result strongly suggests that the proton movement plays a more important role for the charge storage than the anion movement. In such LbL films composed of Ru complexes that exhibit PCET-type redox reactions, the capacitance is drastically improved with an increasing number of layers and using protons as charge carriers.

Salting-in/Salting-out Mechanism of Carbon Dioxide in Aqueous Electrolyte Solutions

The solvation of carbon dioxide in sea water plays an important role in the carbon circle and the world climate. The salting-out/salting-in mechanism of CO2 in electrolyte solutions still remains elusive at molecule level. The ability of ion salting-out/salting-in CO2 in electrolyte solution follows Hofmeister Series and the change of water mobility induced by salts can be predicted by the viscosity B-coefficients. In this work, the chemical potential of carbon dioxide and the dynamic properties of water in aqueous NaCl, KF and NaClO4 solutions are calculated and analyzed. According to the viscosity B-coefficients, NaClO4 (0.012) should salt out the carbon dioxide relative to in pure water, but the opposite effect is observed for it. Our simulation results suggest that the salting-in effect of NaClO4 is due to the strongly direct anion-CO2 interaction. The inconsistency between Hofmeister Series and the viscosity B-coefficient suggests that it is not always right to indicate whether a salt belongs to salting-in or salting-out just from these properties of the salt solution in the absence of solute.

Solubility of calcium molybdate in aqueous solutions at 573 K and thermodynamics of monomer hydrolysis of Mo(VI) at elevated temperatures

This study presents new experimental results on solubility of synthetic crystalline calcium molybdate, CaMoO4(cr), at 573 K and pressure ~ 10 MPa in aqueous solutions of HCl (10−4–0.02 m), HClO4 (10−4–0.03 m), NaCl (0–3.82 m) and NaClO4 (0.10–1.61 m). In addition, the thermodynamic analysis of literature and own data allowed recommendations of the equilibrium constants, $$\log_{10} {{K}}^{\text {o}}$$ , of the reactions H+ + MoO4 2− = HMoO4 −, MoO3(cr) + OH− = HMoO4 −, MoO3(cr) + H2O(l) = H2MoO4(aq), and 2H+ + MoO4 2− = H2MoO4(aq) at temperatures 273–623 K and the saturated water vapor pressure, P s. Knowledge of the thermodynamic properties of the molybdate ion, MoO4 2− (this work), Ca2+, and of calcium molybdate CaMoO4(cr) allowed calculating the values of the solubility product of this phase at temperatures 273–623 K and P s. The thermodynamic modeling of solubility of CaMoO4(cr) at 573 K and P s in studied aqueous solutions (HCl, HClO4, NaCl, and NaClO4) showed that all our experimental data can be reproduced using the same set of species, which includes only the molybdate ion, MoO4 2−, and products of its hydrolysis, HMoO4 − and H2MoO4(aq). Although the formation of ion pairs involving Na+ and the molybdate and hydrogenmolybdate ions at high temperatures appears likely due to the fall of the dielectric constant of water, the current data do not support the formation of such forms of Mo(VI), at least they are never the dominating species at conditions of presented experiments. The increase of temperature leads to the expansion of the predominance field of the hydrogenmolybdate ion HMoO4 − and of H2MoO4(aq) and the decrease of the relative share of MoO4 2−.

Graphene oxide nanoplatforms to enhance catalytic performance of iron phthalocyanine for oxygen reduction reaction in bioelectrochemical systems

Abstract We report the development of electrocatalysts based on iron phthalocyanine (FePc) supported on graphene oxide (GO), obtained by electrochemical oxidation of graphite in aqueous solution of LiCl, LiClO4, and NaClO4. Structure, surface chemistry, morphology, and thermal stability of the prepared materials were investigated by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, atomic force microscopy (AFM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The catalytic activity toward oxygen reduction reaction (ORR) at neutral pH was evaluated by cyclic voltammetry. The experimental results demonstrate that the oxidation degree of GO supports affects the overall catalytic activity of FePc/GO, due to a modulation effect of the interaction between FePc and the basal plane of GO. On the basis of electrochemical, spectroscopic, and morphological investigations, FePc/GO_LiCl was selected to be assembled at the cathode side of a microbial fuel cell prototype, demonstrating a good electrochemical performance in terms of voltage and power generation.

Negligible cation effect on the vibrational relaxation dynamics of water molecules in NaClO4 and LiClO4 aqueous electrolyte solutions

Negligible cation effects on the vibrational relaxation dynamics of water molecules in NaClO4 and LiClO4 aqueous solutions.

Electron Filtering by an Intervening ZnS Thin Film in the Gold Nanoparticle-Loaded CdS Plasmonic Photocatalyst.

In the gold nanoparticle (Au NP)-loaded CdS film on fluorine-doped tin oxide electrode (Au/CdS/FTO), the localized plasmonic resonance excitation-induced electron injection from Au NP to CdS has been proven by photoelectrochemical measurements. Formation of ZnS thin films between the Au NP and CdS film leads to a drastic increase of the photocurrent under visible-light irradiation (λ > 610 nm) in a 0.1 M NaClO4 aqueous electrolyte solution due to the electron filtering effect. The photocurrent strongly depends on the thickness of the ZnS film, and the maximum value is obtained at a thickness as thin as 2.1 nm. Furthermore, the ZnS overlayer significantly stabilizes the photocurrent of the CdS/FTO electrode in a polysulfide/sulfide electrolyte solution even under the excitation of CdS (λ > 430 nm). This work presents important information about the design for new plasmonic photocatalysts consisting of plasmonic metal NPs and chalcogenide semiconductors with high conduction band edge.