The films formed on the surface of copper during its anodic dissolution in the neutral or acidic sulfate solution were studied with the in-line digital holography. The results showed that the mixture films were formed on the surface of copper in the neutral or acidic sulfate solution: the inner oxide film and the outer salt film. Although there are defects in the oxide film caused by the sulfate ions, the oxide film other than the salt film mainly inhibits the anodic dissolution at the high anodic potentials.
Solid Ag/AgCl reference electrodes (RE) with different electrolytes were assembled and characterized in concrete. The performances have been studied with respect to known RE. And the corrosion states of steel have been investigated with respect to embedded and external REs by different electrochemical techniques. Results revealed that half-cell potential of 0.1, 1 and 4.18 M AgCl RE was 20 mV, −30.5 mV and −54.6 mV, respectively. In addition, 4.18 M AgCl RE exhibited the minimum potential drift, the smallest temperature coefficient value and the best reversibility. These corrosion parameters such as rebar potential, corrosion current density (Icorr) and charge transfer resistance (Rct) obtained for steel with respect to these embedded AgCl REs could clearly differentiate the active condition of steel from the passive condition. Besides, Icorr and Rct obtained for steel with respect to external SCE were usually 2 or 3 times larger than these embedded AgCl REs. In such cases embedded AgCl REs could accurately investigate the corrosion rate of steel in concrete. Moreover, the 4.18 M AgCl RE was recommended to monitor the corrosion condition of steel in concrete structure.
The transfer of photoexcited electrons from a fluorescent dye molecule to a semiconductor electrode is regulated by the interfacial design between the electrode and the dye. In the case of larger functional molecules, the regulation becomes observable because of molecular steric hindrance on the solid electrode surface. We have studied the effectiveness of a “swingable” functional molecule layer on a solid substrate for immobilized catalysts and electrochemical reactions. The swingable molecular interface offers the possibility of a similar outcome in photoexcited current generation. The swingable design of the molecular layer may allow smooth current flow from the dye to the semiconductor electrode, because the dye molecules come in close proximity to the semiconductor surface through the swinging action of the linker molecules. In the present study, FTO (fluorine-doped tin oxide) electrodes were prepared with two types of dye-tagged molecular layers, differing only in the type of linker between the dye and the FTO surface: one with a flexible peptide linker capable of swinging back and forth and around, and the other with a rigid peptide linker. The two dye-sensitized FTO electrodes were assayed using photoexcited current measurements. As per the experimental results, the FTO electrode modified with the swingable linker molecule produced higher photoexcited current than that of the FTO modified with the rigid molecule linker.
Nickel films were electrodeposited from modified Watts baths including glycine of 0.2 mol/l and ammonium sulfate of 0.2 mol/l. Nickel electrodeposits were examined using temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). Higher peaks of m/z = 27 and 52 derived from cyanides were recognized in TPD contour maps of nickel electrodeposits. Furthermore, the XPS N1s spectrum implied that cyanides were present on nickel electrodeposits. Free cyanide ions and total cyanides were detected from glycine solutions using commercial test after electric current of 5 A/cm2 was applied for five hours. To ascertain the electrode side at which cyanides were generated, a salt bridge was arranged between an anode chamber and a cathode chamber, consisting of glycine solution. Results show that cyanides were produced at the anode side after electric current was applied to electrodes in the chambers. These results suggest that cyanides were produced by oxidation of glycine at nickel or platinum anodes in Watts baths including glycine, which was induced by the application of electric currents. Moreover, cyanides remained on nickel electrodeposits after rinsing in water for 10 min as well as electrodeposition baths.
Five reference electrodes (Li/Li+) were embedded around a square lithium-ion battery (LIB) cell equipped with a separated Extra Positive-side (XP) and a separated Extra Negative-side (XN), and electrical potential changes of the positive (P and XP) and negative (N and XN) electrodes against the reference electrodes (Rx; x-1–5) during charge and discharge with connect or disconnect ammeters (between P and XP and between N and XN) were studied. AC impedance measurement also was conducted with the cell. It confirmed that electric current (CP and CN) flowed with the charge and discharge in the direction to ease the state of charge (SOC) level between P and XP and between N and XN. During charge and discharge of the cell, the positive electrode potential at the separated Extra Positive-side (XP-R2(+)) was reached to that at the positive electrode (P-R1), and that at the separated Extra Negative-side (XN-R3(−)) was reached to that at the negative electrode (N-R1). AC impedance spectra (Nyquest plots) of the positive electrode (P-Rx) or the negative one (N-Rx) against the five reference electrodes were quite different with each other. However, the Nyquest plots of P-N and sum of P-Rx and N-Rx were almost identical whether the positive (P and XP) and negative (N and XN) electrodes were connected with ammeters or not.
A layered-spinel composite cathode material, LixMn0.75Ni0.25O(1.75+x/2), with controllable phase composition was synthesized by a hydrothermal method followed by calcination. Composite cathode materials that contained different amounts of spinel were synthesized by adjusting the reaction duration in the hydrothermal process. The spinel phase decreases with increasing reaction time, whereas the layered phase increases. For a hydrothermal time of 10 h, a composite material with 22.42 wt% spinel component and 63.98 wt% layered component showed the best cycle performance of approximately 200 mAh g−1 at 0.5 C rates. When the hydrothermal time was 2 h, a composite material with 34.00 wt% spinel component and 53.53 wt% layered component was obtained. The as-synthesized composite exhibits the highest first discharge capacity (245.3 mAh g−1) and the best rate capability (105.3 mAh g−1 at 5 C), which can be ascribed to an appropriate content of layered and spinel phase; the layered component provides composite structural integrity and the spinel phase enables excellent rate performance.
Poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea] (Polyquaternium-2) was employed as a leveler in the through-hole (TH) electroplating experiments from an acidic sulphate bath. The interaction between Polyquaternium-2 and copper surface was investigated using Field Emission Scanning Electronic Microscope (FE-SEM) and X-ray Photoelectron Spectra (XPS). The electrochemical behavior of Polyquaternium-2 and its interaction with other additives, such as a suppressor and an accelerator were characterized using rotating disk electrode. Polyquaternium-2 could absorb on copper surface to form an adsorption layer and inhibit the copper electrodeposition. As shown in the TH electroplating experiments, a copper deposit with uniform thickness was obtained when 0.17 µmol/L Polyquaternium-2 was added. The addition of Polyquaternium-2 could also increase the cathodic polarization, which is attributed to the adsorption of Polyquaternium-2 on the cathode in the process of TH electroplating. The results indicate that Polyquaternium-2 is an effective leveler used for TH electroplating, having a good synergy with SPS, PEG and Cl−.
SnS2 urchins self-assembled by one dimensional nanorods, being different from the two dimensional flakes, were synthesized by a facile method to work as an anode material in lithium-ion battery. The SnS2 urchins displayed a stable capacity of 600 mAh g−1 at the current density of 100 mA g−1 after 50 cycles. The SnS2 urchins showed better cyclic performance and rate capacity compared with SnS2 flakes. The improved performance was ascribed to the three dimensional structures which can decrease the volume expansion/contraction of SnS2 during cycling; the fatal drawbacks of SnS2 were thus mitigated. The facile and economic preparation route may find suitable application to industrial mass production.
In this investigation, poly[Ni(salen)]/MWCNTs composites (PMCs) were synthesised by electrodeposition method via linear sweep potential (LSP), potentiostatic (PS) and one-step potential pulse (SPP) modes, respectively. It was found that different modes resulted in diverse poly[Ni(salen)] morphologies. With the equal deposition time, the PMCs prepared via PS mode exhibited better capacity performances as electrode materials of supercapacitors. The specific capacitances of products prepared by LSP, PS and SPP modes were 72.8 F g−1, 151.5 F g−1 and 106.2 F g−1 at 0.02 mA cm−2, which is due to the difference of thickness of poly[Ni(salen)] wrapped on MWCNTs and length of poly[Ni(salen)] nano-belt. In addition, all the samples exhibited good reversibility as electrode materials.
In order to simulate high-rate discharge behavior of lithium-ion batteries with composite cathode materials, we applied a single-particle model to each cathode material. In the model, we also included the lithium-ion concentration distribution within the electrolyte to calculate the potential profiles in the liquid phase as well as the temperature dependence of both the diffusion behavior of lithium-ions and the charge-transfer rate constant at the solid-electrolyte interface. The potential responses under high-rate discharge were successfully simulated. In this model, the molar flux of each cathode material was determined under the condition that the closed circuit potential of each single-particle should be equal, and the potential distribution in the electrolyte was calculated using a parabolic lithium-ion concentration. The use of approximate analytical solutions for the diffusion equations enabled the reduction of computational time. The validity of the model was confirmed by the experiments using a half-cell of the composite cathode.