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1.
Voltammetric investigations into the process of anodic decomposition of urea using Ti/Pt, Ti/(Pt-Ir)70:30, Ti/RuO2, Ti/(RuO2-TiO2)40:60, Ti/(RuO2-TiO2-IrO2)20:60:20, Ti/(Ta2O5-IrO2)70:30 electrodes have been carried out. Two anodes namely (Ti/(Pt-Ir)70:30 and Ti/(Ta2O5-IrO2)70:30) were found to be stable enough and indicated the required activity to produce non-toxic N2 and CO2 in place of nitrites and nitrates, the commonly reported electrochemical urea oxidation products. The kinetics of the process in question using the above two electrodes was further examined in a periodic electrolyzer. The effect of the anodic current density (j = 2-10 A/dm2), initial urea concentration (c0M = 1-10 g/dm3) and the concentration of sodium chloride (cNaCl = 1-10 g/dm3) on basic process indices (average rate of urea decomposition, a; current efficiency, Wp, and unit DC power consumption, Zj) was discussed. 相似文献
2.
Wojciech Simka Jerzy Piotrowski Adam Robak Ginter Nawrat 《Journal of Applied Electrochemistry》2009,39(7):1137-1143
Investigations on the anodic decomposition of urea using Ti/Pt and Ti/(RuO2–TiO2)40:60 electrodes were carried out. The kinetics of the process were examined in a periodic electrolyser. The effect of anodic current density, initial urea concentration, and sodium chloride concentration on the effectiveness of the basic process (average rate of urea decomposition, current efficiency, and unit power consumption) is discussed. When a Ti/Pt electrode is applied for urea removal from aqueous solution urea is not decomposed directly at the surface of the electrode, but rather in the bulk of the solution by hypochlorite formed during the process. When the Ti/(RuO2–TiO2)40:60 electrode is used for the removal of urea from aqueous solutions, the reaction of urea with chlorine adsorbed at the electrode predominates. In both cases non-toxic products of urea decomposition (N2, CO2,) are formed. Comparison of the effectiveness of anodic decomposition of urea for the Ti/Pt and Ti/(RuO2–TiO2)40:60 electrodes in the periodic electrolyser at optimum process parameters has revealed that the former electrode is more favorable. 相似文献
3.
《Ceramics International》2023,49(3):4365-4371
In the current work, we provide the electrochemical (EC) characteristics and considerable size of Ca-doped ZnFe2O4 nanoparticles. Mixed transition metal oxides are widely used as excellent electrode materials in superior supercapacitors because of their superior capacitance, low cost, and environmental friendliness. The prepared nanoparticles were characterized by X-ray diffraction (XRD), Field-emission scanning electron microscope (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), and EC methods. The results exhibited that the as-synthesized nanoparticles had a cubic spinel crystal structure and efficient EC properties. The EC properties of the prepared electrodes were explored by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) studies. The Ca0.1Zn0.9Fe2O4 electrode demonstrated a specific capacitance (SC) ～208 Fg-1 at a 2 mV/s scan rate due to significant morphological behavior. Therefore may be the prepared materials are the finest electrodes for supercapacitor applications. 相似文献
4.
Kwang Man Kim Sang Hyo Lee Sanghyo Kim Young-Gi Lee 《Journal of Applied Electrochemistry》2009,39(9):1487-1495
In order to enhance the utilization of active cathode material in lithium rechargeable batteries, physical mixtures of μm-sized LiCoO2 (LCO) and nm-sized Li[Co0.1Ni0.15Li0.2Mn0.55]O2 (LCMNO) were prepared by varying the LCO content, and the physical and electrochemical properties of lithium half-cells utilizing the mixed cathodes were characterized. Our main concern is the packing state between the microparticles and nanoparticles within the electrode, which influences the determination of the electrode density. We found that the electrode composed of 80 wt.% LCO and 20 wt.% LCMNO shows the best performance in capacity retention ratio and high-rate capability, which are comparable to those of LCMNO, due to the superior density in the electrode’s packing state over other samples. 相似文献
5.
The electro‐Fenton (EF) process is a promising method combining electrochemical reactions and Fenton's reagent. In this hybrid process, the electrical current induces the in situ generation of H2O2 via reduction of oxygen, and the catalytic reaction is propagated by Fe2+ regeneration, which can take place by reduction of Fe3+ with H2O2, hydroperoxyl radical, organic radical intermediates, or directly at the cathode. Recent advances in the EF process are discussed and several key variables analyzed, including electrode material, initial pH, and Fenton's reagents, in order to extend the applicability of this technology. 相似文献
6.
The use of a reference electrode (RE) is necessary to independently measure the overpotential of each electrode in solid oxide fuel cells (SOFC). This type of set‐up, known as the 3‐electrode (or 3‐terminal) configuration, can give erroneous results if the RE does not effectively separate the potential of the two active electrodes. In this work, calculations and experiments were performed to verify the effectiveness of the 3‐electrode configuration used in electrochemical impedance spectroscopy (EIS) measurements for studying the kinetics of anodes and cathodes in SOFC. Initially, a theoretical analysis of the impedance distortions in relation to the electrode geometry and configuration is presented and the main causes of distortions are elucidated. Then, this analysis is corroborated by experimental results obtained using two specially designed cells. Calculations and experiments reconfirm that configurations characterised by electrodes of equal area and symmetrical placement do not produce EIS distortions when the electrodes have similar area‐specific polarisation resistances and time constants. Moreover, distortions can be low even in considerably misaligned configurations when electrodes are small and relatively inactive. 相似文献
7.
《Ceramics International》2022,48(12):16667-16676
Delafossites are popularly known materials for thermoelectric and electrochemical device applications due to their layered structural features. In this paper, delafossite CuCrO2 nanoparticles (NPs) have been synthesized using a simple chemical procedure and are investigated as a supercapacitor material. To determine the phases of delafossite CuCrO2 NPs, the morphological and phase formation experiments were conducted using diffraction patterns and microscopic analysis. The cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) studies were performed to evaluate the supercapacitative behavior of delafossite CuCrO2 NPs. As prepared delafossite CuCrO2 NPs based electrode showed an outstanding electrochemical property as compared to annealed delafossite CuCrO2 NPs at 300–500 °C. A good specific capacitance of ～464.7 Fg-1 at 0.01 Vs-1 was found for the fabricated supercapacitor using non-annealed delafossite CuCrO2 NPs based electrode, which was further validated by GCD results. The electrochemical supercapacitor fabricated with both non-annealed and annealed delafossite CuCrO2 NPs displayed considerably the outstanding cycling stability by maintaining up to ～88% after 5000 cycles. This work sets the pace for a new and efficient method of preparing delafossite CuCrO2 for high-performance electrochemical supercapacitors. 相似文献
8.
《Ceramics International》2016,42(16):18173-18180
It is essential to develop new electrode materials for electrochemical energy storage to meet the increasing energy demands, reduce environmental pollution and develop low-carbon economy. In this work, binder-free NiCo2S4 nanorod arrays (NCS NRAs) on nickel foam electrodes are prepared by an easy and low energy-consuming route. The electrodes exhibit superior electrochemical properties both for alkaline and Li-ion batteries. In 3 M KOH electrolyte, the NCS NRAs achieve a specific capacity of 240.5 mA h g−1 at a current density of 0.2 A g−1, and 105.7 mA h g−1 after 1500 cycles at the current density of 5 A g−1 with capacity retention of 87.3%. As the anode for LIBs, it shows a high initial capacity of 1760.7 mA h g−1 at the current density of 100 mA g−1, corresponding coulombic efficiency of 87.6%, and a rate capacity of 945 mA h g−1 when the current density is improved 10 times. Hence, the NiCo2S4 nanorod arrays are promised as electrode materials with competitive performance. 相似文献
9.
10.
The 3‐electrode configuration is commonly applied to quantify the overpotential of anodes or cathodes in solid‐oxide fuel cells (SOFC). In this type of set‐up, a reference electrode (RE) is used to isolate the potential loss of one electrode from that of the entire cell; however, erroneous results can be obtained whenever the RE does not precisely separate the potential drop between the two active electrodes. In this study, we present the results of a theoretical and experimental analysis focused on verifying the effectiveness of the 3‐electrode configuration in electrochemical impedance spectroscopy measurements for the kinetic characterisation of SOFC electrode reactions. The focus of this paper is on the distortion of impedance measurements caused by differences in the area‐specific polarisation resistance and impedance time constants of the working and counter electrodes. The results obtained numerically and experimentally, both for planar and tubular SOFC cell geometries, prove the reliability of the theoretical model used. From the systematic simulation presented here and in our previous work, it was possible to formulate general guidelines for the design of 3‐electrode experimental SOFC. The theoretical model used here can also be used to verify the consistency of EIS measurements obtained with thin planar cells. 相似文献
11.
Titanium nitride (TiN) is attracting attention as a promising material for low temperature proton exchange membrane fuel cells. With its high electrical conductivity and resistance to oxidation, TiN has a potential to act as a durable electrocatalyst material. Using electrochemical and spectroscopic techniques, the electrochemical oxidation properties of TiN nanoparticles (NP) are studied under PEM fuel cell conditions and compared with conventional carbon black supports. It is observed that TiN NP has a significantly lower rate of electrochemical oxidation than carbon black due to its inert nature and the presence of a native oxide/oxynitride layer on its surface. Depending on the temperature and the acidic media used in the electrochemical conditions, the open circuit potential (OCP) curves shows the overlayer dissolved in the acidic solution leading to the passivation of the exposed nitride surface. It is shown that TiN NP displays passive behavior under the tested conditions. The XPS characterization further supports the dissolution argument and shows that the surface becomes passivated with the O-H groups reducing the electrical conductivity of TiN NP. The long-term stability of the Pt/TiN electrocatalysts is tested under PEM fuel cell conditions and the trends of the measured electrochemical surface area at different temperatures is shown to agree with the proposed passivation model. 相似文献
12.
《Ceramics International》2017,43(5):4159-4165
MnGaxCr2−xO4 (MGCO, x=0.1, 0.2, 0.4, 0.8, 1) oxides are synthesised using a citric acid nitrate combustion method. The influence of Ga substitution on the structure, electrical conductivity and electrochemical performance are systematically investigated. The chemical and thermal compatibility of MGCO materials with yttrium-stabilised zirconia (YSZ) are also studied. All the samples exhibit a single phase spinel structure. Thermal expansion coefficients (TECs) of the MGCO oxides are in the range of 9–12×10−6 K−1, indicating a good thermal match with the YSZ electrolyte. No chemical reactions are detected between MGCO materials and YSZ, indicating their good chemical compatibility with YSZ. The magnitude of electrical conductivity of all the obtained samples is in the order of about 10−3 S cm−1at 800 °C measured in air. The polarisation resistance reaches a value as low as 5.2 Ω cm2 for x=0.4 at 800 °C. The preliminary results demonstrate that MGCO materials could be used as electrode support materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). 相似文献
13.
《Ceramics International》2019,45(1):674-680
Nickel-rich lithium material LiNixCoyMn1-x-yO2(x > 0.6) becomes a new research focus for the next-generation lithium-ion batteries owing to their high operating voltage and high reversible capacity. However, the rate performance and cycling stability of these cathode materials are not satisfactory. Inspired by the characteristics of Y2O3 production, a new cathode material with ultrathin-Y2O3 coating was introduced to improve the electrochemical performance and storage properties of LiNi0.8Co0.1Mn0.1O2 for the first time. XRD, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS) and XPS were used to mirror the crystal and surface of LiNi0.8Co0.1Mn0.1O2 particles, results i that a uniform interface formed on as-prepared material. The impacts on the electrochemical properties with or without Y2O3 coating are discussed in detail. Notably, galvanostatic discharge-charge tests appear that Y2O3-coated sample especially 3% coating displayed a better capacity retention rate of 91.45% after 100 cycles than the bare one of 85.07%. 相似文献
14.
Many devices used in catalysis are based on high surface area materials in which catalytic reactions are carried out inside pores, channels and other confined cavities for which the deposition of catalyst thin films is required. This paper provides an overview of the methods in use for the preparation and characterization of catalyst thin films, and focuses more specifically on thin films involved in the electropromotion of catalysis (EPOC). In fact, EPOC or NEMCA (Non-Faradic Electrochemical Modification of Catalytic Activity) have shown the importance of being able to combine electrical contacts between catalytic metals and ion conducting oxide layers as well as to develop in the same system catalytic materials with large specific surface area. The different aspects of thin film preparation and characterization are described in relation to catalyst thin films deposition. Multimodal and hierarchic porous structures can be obtained from the assembly of catalyst thin films with various carrier materials, anticipating more efficient catalytic systems. Chemical and physical coating techniques are compared with a special attention on those useful for the preparation of thin films with controlled porous structure and morphology. With regard to EPOC systems, electrode and electrolyte materials of interest for electrochemical catalytic devices are listed and typical examples of systems based on electrocatalyst thin films are given. 相似文献
15.
Gérard Lizard 《European Journal of Lipid Science and Technology》2016,118(2):135-136
It is commonly accepted that cholesterol oxide derivatives, also named oxysterols, are 27 carbon‐atom molecules deriving either from enzymatic and non‐enzymatic oxidation of cholesterol. Most of these compounds can be synthesized by more or less difficult and time consuming chemical reactions, and some of them have been discovered before the identification of the enzymes [mainly cytochrome P450 enzymes (CYP enzymes)] involved in their biosynthesis. A wide range of biological activities depends on oxysterols. Some oxysterols are also involved in the synthesis of cholesterol metabolites which have various properties. The paper by Weber et al. in this issue of European Journal of Lipid Science and Technology is of interest because it reports that an electrochemical oxidation of cholesterol rapidly generates numerous oxysterols which are usually generated either by enzymatic processes in vivo or under the action of different chemical and physical agents (free radicals, sun light, …) in vivo or not. This has a crucial importance and suggests that the border between enzymatic and non‐enzymatic generation of oxysterols should be reconsidered, at least for some of these compounds. Consequently, these observations may have major chemical and physiopathological significance. 相似文献
16.
The electrochemical oxidation of chloranilic acid (CAA) has been studied in acidic media at Pb/PbO2, boron-doped diamond (Si/BDD) and Ti/IrO2 electrodes by bulk electrolysis experiments under galvanostatic control. The obtained results have clearly shown that the electrode material is an important parameter for the optimization of such processes, deciding of their mechanism and of the oxidation products. It has been observed that the oxidation of CAA generates several intermediates eventually leading to its complete mineralization. Different current efficiencies were obtained at Pb/PbO2 and BDD, depending on the applied current density in the range from 6.3 to 50 mA cm−2. Also the effect of the temperature on Pb/PbO2 and BDD electrodes was studied.UV spectrometric measurements were carried out at all anodic materials, with applied current density of 25 and 50 mA cm−2. These results showed a faster CAA elimination at the BDD electrode. Finally, a mechanism for the electrochemical oxidation of CAA has been proposed according to the results obtained with the HPLC technique. 相似文献
17.
Kumaravelu Thanigai Arul Elayaperumal Manikandan Rasiah Ladchumananandasivam Malik Maaza 《Polymer International》2016,65(12):1482-1485
Uniform nanosheet‐like structures were synthesized by the polymer based co‐precipitation route. Different concentrations of polyvinyl alcohol (pure (0 g), 0.2 g and 0.5 g) were added to nickel (Ni) and cobalt (Co) ion co‐doped ferrite magnetic nanoparticles. X‐ray diffraction confirmed a spinel structure phase of the Ni ? Co ferrites. Enhanced average crystallite size (6.7%) of the Ni ? Co ferrites was found on polymer incorporation. The molecular functional group of polyvinyl alcohol and Ni ? Co ferrites was confirmed by infrared and Raman spectroscopy techniques. On adding polymer, the spherical morphology of the Ni ? Co ferrites was tailored to nanosheets (200 nm × 300 nm). Therefore, the polymer based co‐precipitation technique is an inexpensive, simple and effective route to engineer the morphology of the magnetic nanostructure and could be useful for gas sensor and magnetic sensors. © 2016 Society of Chemical Industry 相似文献
18.
Pt/CeO2/CNT catalysts were prepared by adsorbing Pt nanoparticles on the supports of CNTs coated with CeO2. The electrocatalytic performances in respect to the electrooxidation of chemisorbed CO were tested using potential step and stripping voltammetry methods under variable sweep rate and temperature conditions. At 10 mV s–1, the CO stripping voltammogram exhibited the peak splitting phenomenon. The oxidation charge and the peak potential of the two voltammetric peaks changed regularly with the number of Pt and CeO2 neighbours, the sweep rate, and the temperature. We considered that the low potential peak originated from the reaction of COads with hydroxyl groups on CeO2 adjacent to Pt sites, while the high potential peak came from the reaction of COads with hydroxyl groups produced on pure Pt. Furthermore, the experimental results of the peak potential against the logarithm of the sweep rate and the logarithm of the current maximum time against the step potential were plotted and intersecting lines with different slopes in high and low potential regions in the plot were observed. The lines intersected at lower potentials on the Pt/CeO2/CNT electrode than on the Pt/CNT electrode, which was attributed to the contribution of hydroxyl groups on CeO2. 相似文献
19.
The development of active corrosion protection systems for metallic substrates is an issue of prime importance for many industrial applications. Nanostructured chitosan/ZnO nanoparticle films were coated on mild steel by sol–gel process, dip coating technique. Sol–gel protective coatings have shown excellent chemical stability, oxidation control and enhanced corrosion resistance for metal substrates. Further, the sol–gel method is an environmentally friendly technique of surface protection which has traditionally been used for increasing corrosion resistance of metals. Films so formed were characterized by UV–vis absorption spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray fluorescence spectrometry (EDX). Corrosion protection behavior of these coated mild steel substrates in 0.1 N HCl solutions was evaluated by potentiodynamic polarisation studies (Tafel), linear polarisation studies (LPR), electrochemical impedance spectroscopy studies (EIS). 相似文献
