Research and Development Techniques 1: Potentiodynamic Studies of Copper Metal Deposition

The electrochemistry of copper (II)/(I) ions in aqueous chloride solution, at pH2, is used to demonstrate the application of voltammetry techniques in characterising electrode processes. The electrolyte used is 1.5 M sodium chloride containing 20 to 50 × 10^?3 M cupric chloride at 20°C, in which both Cu(II) and Cu(I) ions are stable. A platinum rotating disc electrode (RDE, radius 0.365 cm) is used to provide controlled mass transport under laminar flow conditions. Cyclic voltammetry, at a stationary disc electrode, is used to characterise the general electrochemistry. Four current peaks due to reduction of Cu(II) ions to Cu(I) ions, deposition of Cu from Cu(I) ions, anodic stripping of Cu to form Cu(I) ions and oxidation of Cu(I) ions to Cu(II) ions are seen. Analysis of the Cu(II)/Cu(I) couple indicates a reversible process. A potential sweep rate experiment allows the diffusion coefficient of Cu(II) ions to be calculated. The anodic stripping peak in the cyclic voltammogram is used to estimate the amount of copper deposited. Reduction of Cu(II) to Cu(I) then to Cu is examined at a range of rotation speeds (150–1870 rpm) using linear sweep voltammetry at the RDE. Mass transport data are obtained in the form of limiting current density as a function of the RDE speed, allowing the diffusion coefficients of Cu(II) and Cu(I) ions to be calculated.     

Electrodeposition of Tin Alloys from Alkaline Stannate Baths

The paper reports on a small development programme designed to concentrate on devising a relatively simple technique for the deposition of copper only in drilled holes of a conventionally produced printed wiring board. It is essential to start with a laminate containing catalysed resin base, producing the printed wiring pattern in the normal manner and plating up holes using autocatalytic electroless copper. Thickness measurements and microsections of electroless copper deposits have been obtained and appear to be encouraging.     

多线程内存数据库服务器设计

文章介绍了一个多线程内存数据库服务器（MTMDS）,由于采用多线程技术,克服了多进程体系结构资源消耗多、进程调度开销大、难以实现大容量共享存储等主要缺陷。文中详细阐述了采用“移动平均反馈”事务预测法（MMFP）的实时数据库引擎（RDE）、动态内存管理（DMM）、用户数据索引及并发控制。     

Electrochemical corrosion of unalloyed copper in chloride media--a critical review

The literature dealing with the electrochemical corrosion characteristics of unalloyed copper in aqueous chloride media is examined. The enormous quantity of polarisation and mixed/corrosion potential data that has been made available in the literature over the last 50 years has been compiled and discussed in a comprehensive review. For a wide range of electrode geometries, the importance of the chloride ion and the mass transport of anodic corrosion products on the corrosion behaviour of copper are made clear for both freshly polished and ‘filmed’ surfaces.     

Insight into the electroreduction of nitrate ions at a copper electrode, in neutral solution, after determination of their diffusion coefficient by electrochemical impedance spectroscopy

The electrochemical reduction of nitrate ions at a copper electrode in an unbuffered neutral aqueous solution is studied. Using a two compartment electrochemical cell, three stationary cathodic waves, noted P1, P2 and P3, were evidenced by cyclic voltammetry at −0.9, −1.2 and −1.3 V/SCE, respectively. By comparing the electrochemical response of nitrate and nitrite containing solutions, P1 was attributed to the reduction of nitrate to nitrite. In order to assign P2 and P3 features by determining the number of electrons involved at the corresponding potential, rotating disk electrode experiments at various rotation speeds, combined with linear sweep voltammetry, were performed. Current data analysis at a given potential was carried out using Koutecky-Levich treatment taking into account water reduction. Confident values of the diffusion coefficient D of nitrate ions were assessed by electrochemical impedance spectroscopy for nitrate concentrations of 10⁻³, 10⁻² and 10⁻¹ M. For a nitrate concentration of 10⁻² M, D was found to be 1.31 × 10⁻⁵ cm² s⁻¹ allowing the number of electrons to be determined as 6 for P2 and 8 for P3, in accordance with nitrate reduction into hydroxylamine and ammonia, respectively. The formation of hydroxylamine was confirmed by the observation of its reoxidation at a Pt microelectrode present at the Cu electrode/nitrate solution interface.     

Effect of hydrodynamic conditions on the inhibition performance of l-methionine as a “green” inhibitor

Influence of hydrodynamic conditions on the behavior of l-methionine (l-MTI) as a green organic inhibitor was studied using mild steel rotating disc electrode. Electrochemical impedance spectroscopy (EIS) and polarization measurements were carried out in the absence and presence of inhibitor in 1 M H₂SO₄ solution under static conditions and at different rotation speeds; the inhibitor concentration was 5 × 10⁻³ M in all tests. The open circuit potentials (OCP) were measured versus time in all studied rotation speeds; it was found that the OCP shifted toward more positive potentials as the rotation speed increased. It was also found that the inhibition efficiencies for still electrode and low speed rotations did not have noticeable changes, but in much higher rotation speeds, increased efficiencies were observed. This behavior could be attributed to the enhanced mass transport of inhibitor molecules from bulk to the metal surface in high rotation rates.     

Study of thrust vector control for the rotating detonation model engine

The detonation wave in a rotating detonation engine is highly adaptable to the incoming flow, making the wave easier to control. In this study, a numerical simulation method is used to analyze the working process and flow field structure of a rotating detonation model engine with dual cavity injection of an H₂/air mixture by controlling the injection pressure ratio of the dual cavity and the number of detonation wave heads. It is found that the rotating detonation engine offers the possibility to control the thrust vector with two different modes. The first is a one-cycle alternate control mode with a small injection pressure ratio. Here two deflections occur in different directions occur across one detonation wave propagation cycle, but the overall deflection direction is in the low-pressure region. The second is a one-way control mode, with a large injection pressure ratio, and the deflection direction towards the low-pressure region. For the multi wave-mode, it belongs to one-way control mode because of constant deflection direction in the low-pressure area. From the perspective of thrust distribution along the circumference, the one-way control strategy satisfies the ability of a rotating detonation thrust vector control.     

Rapid rotating-disk-electrode evaluation of catalyst performance and durability during transient conditions: The Pt–Hf binary system

A comprehensive set of rotating disk electrode (RDE) tests has been developed to test the suitability of fuel cell catalyst candidates for use as either anode or cathode catalysts for transient conditions. The activity for Hydrogen Oxidation reaction (HOR), Oxygen Reduction reaction (ORR) and Oxygen Evolution reaction (OER) is tested together in one protocol. A total of 5 Pine Instruments RRDE test stations have been set up with automatic gas flow switching and computer software to control all aspects of the data collection process. The user simply sets up the electrochemical cell with a gas bubbler, reference electrode, counter electrode and sample and then selects a series of tests to be run. The software then switches gas flow, rotation rates and potentiostat set up files automatically. This infrastructure allows the rapid characterization of catalyst candidate materials. The series of tests is described, along with the purpose of each test in the protocol. As an example, the data collected from a Pt_1−xHf_x composition spread is presented. The optimal composition is found to be approximately 30 at.% Hf, when the ORR performance begins to decrease at a faster rate than the HOR performance and the OER current at 1300 mV is also a maximum. However, it was determined that from an applied point of view the drop in ORR performance was insufficient to adequately protect the cathode from the effects of the transient potentials during start-up of the fuel cell.     

The kinetics of the Cu/Cu redox couple in deep eutectic solvents

Kinetics of electron transfer of the Cu(I)/Cu(II) redox couple at a platinum electrode has been studied with chronoamperometry, cyclic voltammetry and impedance spectroscopy in a deep eutectic solvent consisting of choline chloride and ethylene glycol. At 25 °C, the reaction was found to be quasi-reversible with a relatively high rate constant k⁰ of 9.5 ± 2 × 10⁻⁴ cm s⁻¹, and a charge transfer coefficient α of 0.25 ± 0.05. Diffusion coefficients for the Cu(I) and Cu(II) complexes were determined to be 2.7 ± 0.1 × 10⁻⁷ and 1.5 ± 0.1 × 10⁻⁷ cm² s⁻¹, respectively. The viscosity of the electrolyte was 41 ± 3 mPa s. The temperature dependency was also investigated. The activation energy of mass transfer was found to be 27.7 ± 1 kJ mol⁻¹ and that of electron transfer 39 ± 7 kJ mol⁻¹. Speciation of the Cu(I) and Cu(II) complexes was determined using UV–VIS spectroscopy, and the prevailing Cu(I) complex was found to be [CuCl₃]²⁻ and that of Cu(II) [CuCl₄]²⁻.     

Measurement of oxygen reduction activities via the rotating disc electrode method: From Pt model surfaces to carbon-supported high surface area catalysts

The aim of this report is to scrutinize the thin-film rotating disc electrode (TF-RDE) method for investigating the electrocatalytic activity of high surface area catalysts. Special emphasis is given to the oxygen reduction reaction (ORR) on carbon-supported platinum catalysts. On the basis of measurements on four different Pt catalyst samples with various average particle sizes, it is demonstrated in detail how the intrinsic properties of the catalyst, i.e., the mass activity (A/g_Pt) and the specific activity (A/m²_Pt), are evaluated. The potential sources of error are critically discussed and guidelines for the measurements are given. Furthermore, the specific ORR activities determined for the different catalyst samples are analyzed and compared to polycrystalline Pt. The previously reported effect of the particle size on the specific activity for the ORR is interpreted on the basis of the shift in the potential of zero total charge and the concomitant alteration of the adsorption properties.