Acid Concentration In Electrolyte Research Articles

Formation and Characterization of Dispersed Mixed Iron-titanium Oxide Systems by Electrochemical Method

Aims: Anodic polarization behavior of a combined iron-titanium electrode (two metals in electrical contact with each other) in aqueous solutions containing halide ions (F- and Cl-) was studied. Methods: he joint anodic dissolution of titanium and iron with subsequent thermal treatment makes it possible to obtain precursors of a highly dispersed mixed oxide system Fe2O3-TiO2. The phase and elemental composition and structural characteristics of obtained products were examined using X-ray diffraction and scanning electron microscopy. It has been experimentally confirmed that via changing the anode current density, hydrofluoric acid concentration in electrolyte and ratio of the working surface area of contacting metals, it is possible to effectively control the rate of anodic reactions and phase composition and morphology of anodic oxidation products for iron and titanium components in a combined electrode. Results: The main results of this study are as follows: Electrochemical method for the synthesis of complex dispersed oxide system Fe2O3-TiO2 based on joint anodic oxidation of contacting metals in aqueous media was suggested. Relationships between parameters of the electrochemical process and characteristics of the synthesized oxide system were revealed. Conclusion: By varying the parameters of the electrolysis process, it is possible to prepare complex oxyhydroxides with different ratios of iron and titanium, which makes it possible to synthesize precursors of iron titanates of preset composition and structure.

Transition Layer Thickness Control in Additive-Assist Electroplated Nanotwin Copper

Unidirectional (111) nanotwin copper has shown exceptional performance such as thermal stability, mechanical strength, fatigueless behavior, electromigration resistance, electric conductivity, low bonding temperature, and ultra-large grain growth. These unique properties make it a promising solution to several IC applications including fine line RDL in fan-out WLP, copper direct bond in 3D IC vertical interconnect, high conductivity Cu interconnect for VLSI etc. Both electrochemical deposition and physical vapor deposition are able to form such microstructure, and electrochemical deposition is considered the suitable production method in terms of process flexibility, throughput, and overall cost. Direct current was successfully applied to nanotwin copper formation in many reports, but the common feature of these tests is using low or no acid electrolyte with pH around 1. This approach greatly hinders the industrial implementation because of poor deposit uniformity from low electrolyte conductivity. Pulse plating with low duty cycle was also tried, and able to produce nanotwin in high acid electrolyte. However, throughput and hardware cost are the downside of this method. Another approach is DC plating with additives of crystal plane adsorption selectivity, and then electrolyte acid concentration over 100g/L could be used to form nanotwin copper. During the preferred orientation grain development, a micrometer transition layer between non-nanotwin substrate and columnar nanotwin grain is formed. The transition layer thickness is found sensitive to substrate copper grain orientation as well as electrolyte acid concentration, and may dominate the material property when overall deposition thickness reduces in fine line RDL application. In order to reduce the transition layer thickness, two additive modification approaches are demonstrated in this paper. The first one is to increase columnar grain nucleation density by reducing nucleation overpotential, and the second one is to increase lateral grain growth rate by increasing nucleation overpotential. The prior approach results in smaller columnar grain diameter, and the later one results in larger columnar grain diameter. Both approaches are effective in reducing transition layer thickness. Figure Caption: Transition layer boundary represented by green dash line on TiW/Cu substrate. (a) thick, irregular transition layer with nt-Cu additive. (b) thin transition layer with modified nt-Cu additive increasing substrate nucleation sites. Figure 1

A high power density, high efficiency hydrogen–chlorine regenerative fuel cell with a low precious metal content catalyst

We report the performance of a hydrogen–chlorine electrochemical cell with a chlorine electrode employing a low precious metal content alloy oxide electrocatalyst for the chlorine electrode: (Ru0.09Co0.91)3O4. The cell employs a commercial hydrogen fuel cell electrode and transports protons through a Nafion membrane in both galvanic and electrolytic mode. The peak galvanic power density exceeds 1 W cm−2, which is twice previous literature values. The precious metal loading of the chlorine electrode is below 0.15 mg Ru cm−2. Virtually no activation losses are observed, allowing the cell to run at nearly 0.4 W cm−2 at 90% voltage efficiency. We report the effects of fluid pressure, electrolyte acid concentration, and hydrogen-side humidification on overall cell performance and efficiency. A comparison of our results to the model of Rugolo et al. [Rugolo et al., J. Electrochem. Soc., 2012, 159, B133] points out directions for further performance enhancement. The performance reported here gives these devices promise for applications in carbon sequestration and grid-scale electrical energy storage.

Electrochemical Oxidation of Phenol

The electrochemical oxidation of phenol was studied using a packed bed reactor of pellets with recirculating anolyte in order to follow phenol loss and benzoquinone, maleic acid, and carbon dioxide formation. A carbon mass balance revealed a significant fraction of additional by‐products for initial phenol concentrations of ⩾ 0.014M. Benzoquinone and carbon dioxide formation were measured as a function of applied current, initial phenol concentration, electrolyte acid concentration, temperature, and dissolved oxygen. Benzoquinone formation was favored by high current and acid concentration and by low phenol concentration, temperature, and dissolved oxygen at relatively short electrolysis times. Carbon dioxide formation depended on the degree of the oxidation and was favored by high current, acid concentration, temperature, dissolved oxygen, and by low phenol concentration.