Effect Of Electrolyte Temperature Research Articles

Effect of Electrolyte Temperature on Plasma Electrolytic Oxidation of Pure Aluminum

Plasma electrolytic oxidation (PEO) is normally carried out under conditions with electrolyte cooling. However, the effect of the temperature of the electrolytes on the PEO behavior and properties of the resulting coatings is seldom investigated. In this study, PEO of pure Al was carried out in a dilute aluminate electrolyte with the electrolyte temperature being controlled under low (~10–30 °C), medium (~40–50 °C) and high (~70–80 °C) temperature ranges, respectively. The morphology, microstructure, composition and phase component of the coatings fabricated under the different temperature ranges were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The corrosion resistances of the coatings were evaluated by electrochemical methods. The hardness of the coatings and substrate following the PEO treatment in the different electrolyte temperature ranges were also tested. It was found that a higher electrolyte temperature resulted in a higher growth rate and rougher coatings. Moreover, the α-Al2O3 content was reduced as the electrolyte temperature increased. The highest corrosion resistance was registered for the coating obtained under the lowest temperature range, whereas the corrosion resistance of the coating obtained under the highest temperature range was the worst. The higher growth rate under high electrolyte temperatures was associated with the increased kinetics of the PEO reactions. However, the temperature of the electrolyte should be controlled under a suitable range to ensure reasonable coating properties.

Multi-objective optimization of water electrolysis based on coupling model of electrochemistry and multiphase flow

In this paper, a coupling model of electrochemistry and multiphase flow is established, which considers the interaction between electrochemical reactions and the flow regime of gas and liquid. Based on the ANOVA analysis, response surface methodology, and multi-objective optimization, the effects of electrolyte temperature, electrolyte concentration, and inlet velocity on the performance of water electrolysis are further studied. The calculation results show that with the increase of temperature and concentration of electrolyte, the average value of current density gradually increases, but the uniformity of current density and the specific energy consumption will deteriorate. Increasing the inlet velocity can simultaneously improve the average value and the uniformity of current density and specific energy consumption. And the intelligent optimization algorithm is introduced into the field of water electrolysis to obtain the local sensitivity and the Pareto front. Three groups of optimized parameters are determined. Compared with the original parameters, the average value of the current density of the optimized parameters increases by 7.04 % on average, the variance of the current density of that decreases by 28.14 % on average, and the specific energy consumption of the optimized parameters reduces by 45.90 % on average. The empirical correlation between operating parameters and electrolyzer performance is obtained. The research results provide guidance for the design of electrolyzer.

The effect of electrolyte temperature on the growth, morphology, and properties of porous anodic tin oxide films

The effect of electrolyte temperature on the anodic formation of nanoporous tin oxide layers, their morphology and properties was studied in detail. Electrochemical synthesis of SnOx films was carried out in both acidic (H2C2O4) and alkaline (NaOH) electrolytes at various potentials. Differences in morphological features of as-generated films and the kinetics of their formation were carefully investigated from FE-SEM images. The effect of anodizing temperature was successfully verified revealing its undeniable importance when designing the anodization procedure. For instance, both in acidic and alkaline electrolytes, applying too low temperatures results in formation of cracked oxide layers with the least open pores or compact surface, while too high temperatures (≥40 °C) leads to obtaining films with clogged pores due to the partial etching of the material by the electrolyte. Anodizing temperature was also found to be a crucial parameter responsible for the type of morphology of the synthesized materials (compact or porous layers or even crater-like hierarchical structures) when the process is carried out at higher potentials (here 9 V). Finally, we have proved that the impact of electrolyte temperature on the crystallinity of the anodic tin oxide layers is negligible, whereas the photoelectrochemical activity is significantly influenced due to the tight relation with the morphology of as-synthesized materials.

Insight into effect of electrolyte temperature on electroactivity degradation of conducting polypyrrole in NaOH

The irreversible electroactivity degradation is a key and broad issue for conducting polypyrrole (PPy). PPy degradation involves chemical and electrochemical processes affected by various factors, including doping anions, electrolyte pH, dissolved oxygen (DO), temperature (T), electrode potential, etc. This study probes into the effect of T on electroactivity degradation of PPy in 0.5 M NaOH. Increasing the T (25~80 oC), the degradation kinetics of PPy remains the same first-order relationship, while the degradation rate constant is significantly affected, which shows a maximum value in 50 oC deaerated or 70 oC aerated NaOH, respectively. In deaerated NaOH, the open circuit potential of PPy becomes very negative to reach a reduction state with increasing T, which may restrain penetration of OH- ions into PPy film to inhibit the degradation in its interior. In aerated NaOH, the concentration of DO lowers with increasing T to suppresses the electrochemical process in PPy degradation and decrease its degradation. DO still plays a crucial role in the PPy degradation process at high T. A thorough understanding of the effect of electrolyte T on electroactivity degradation of PPy would offer valuable concepts for in-depth and comprehensive insights into the mechanisms and kinetics of PPy degradation.

Effect of Electrolyte Temperature on Properties of Nickel Film Coated onto Copper Alloy Fabricated by Electroplating

Effect of Electrolyte Temperature on Properties of Nickel Film Coated onto Copper Alloy Fabricated by Electroplating

Effect of Electrolyte Temperature and Anodization Time on Formation of TiO2 Nanotubes for Biomedical Applications

We have investigated the formation of self-organized titanium oxide nanotube layers by anodic oxidation on titanium alloys in electrolyte solutions with different temperatures (5, 10, 25, 30, 50 and 70 °C). Pore diameter and the wall thickness of nanotube arrays were controlled by varying anodization time and temperature. We have observed significant outcomes in the formation of TiO2 nanotube arrays at 25 °C with an average inner pore diameter of 125 nm, length of ∼250 nm, the wall thickness of 30 nm and an inter-tube space 35 nm. Nanotube arrays were smooth and circular without any defect in morphology. In addition, anodization of Commercially Pure Titanium (CP Ti) and titanium alloys (Ti-6Al-4 V, Ti-6Al-7Nb, Ti-13Nb-13Zr, and β-21 s) was carried out at optimized parameter to understand their significance on TiO2 nanotube arrays formation.

Effects of Electrolyte Temperature during Anodization on Properties of ZrO2-coated Al Foils

Effects of Electrolyte Temperature during Anodization on Properties of ZrO₂-coated Al Foils

Enhanced thermoelectric properties of electropolymerized poly (3,4-ethylenedioxythiophene) thin films by optimizing electrolyte temperature and thermal annealing temperature

Effects of electrolyte temperature and annealing temperature on ClO4-doped poly (3,4-ethylenedioxythiophene) (PEDOT) thin films were investigated. Prior to the electropolymerization of the thin films, we performed cyclic voltammetry (CV) analysis while changing the electrolyte temperature between 0 °C and 60 °C. The current density increased with increasing electrolyte temperature, and the onset oxidation potential was mostly constant at approximately 1.3 V. From the CV analysis, we determined the electropolymerization condition of electrolyte temperature 50 °C and applied potential 1.52 V. Following the electropolymerization of the PEDOT thin films, thermal annealing was implemented in the range 80 °C to 140 °C with a mixture of argon (95%) and hydrogen (5%) gases at atmospheric pressure. ESR analysis showed that the intensity of the ESR spectra decreased with increased annealing temperature because of the decrease of charge-trapping related defects. In the annealed samples, the electrical conductivity of PEDOT thin films increased and the Seebeck coefficient decreased with increased annealing temperature; this was supported by the ESR analysis results. As a result, PEDOT thin films annealed at 80 °C and 100 °C exhibited a maximum power factor of 0.8 μW/(m·K2). Therefore, we conclude that the moderate annealing treatment enabled the thermoelectric performance to improve.

Effect of Joule Heating on Formation of Porous Structure of Thin Oxalic Acid Anodic Alumina Films

The effect of electrolyte temperature and anodizing voltage on the surface morphology of thin oxalic acid anodic alumina films formed on the SiO2/Si and glass-ceramic substrate was studied. It was shown when anodizing voltage increased from 10 to 20 V pore diameter increased from 12.2 to 15.5 nm and from 14.5 to 17.7 nm for the films formed on SiO2/Si and glass ceramic substrates, respectively. For the films formed at anodizing voltage (Ua) 30 and 40 V, pore diameter was 20.5 and 25.5 nm, respectively, and it was independent of the substrate type. It was demonstrated that when thin aluminum films were oxidized in oxalic acid, anodizing voltage of 30 V was a turning point at which the mechanism of the formation of anodic porous structure changed. By performing the experiments on the substrates with different thermal conductivity, we showed that at Ua < 30 V generated in the barrier layer Joule heating was absorbed by the substrate, but at Ua > 30 V the heat warmed up the electrolyte at the pore bottom that resulted in the changes of morphology of the films. We also suggested the empiric equation that connected pore diameter, anodizing current and generated Joule heating.

Effect of electrolyte temperature on the cathodic deposition of Ge nanowires on in and Sn particles in aqueous solutions

The results of studying the growth of filamentous Ge structures in aqueous electrolytes at various temperatures using In and Sn nanoparticle arrays as nucleation sites are given. The temperature of Ge cathodic deposition process from aqueous solutions has a significant effect on the layer structure deposited onto the surface. In the presence of metal particles in the molten state, filamentous Ge structures grow due to the cathodic reduction of Ge-containing ions on the electrode surface, followed by dissolution and crystallization in the melt at the substrate interface. The results obtained show the crucial role of liquid metal particles during the electrochemical formation of germanium nanowires.

Effect of electrolyte temperature on Faradaic effect in electrochemical microdrilling

Electrochemical micromachining (ECµM) is an emerging non-conventional manufacturing technology suitable for the fabrication of micro-sized components on a wide range of electrically conductive materials. This study emphasises on the effects of electrolyte temperature on the Faradaic effect during electrochemical microdrilling on nickel plates by a cylindrical microtool made of tungsten. A short cylindrical microtool of 43 µm in diameter near to the tool tip and 53 µm mean diameter was selected, and allowed to machine on nickel plate. During machining, only the electrolyte temperature was varied keeping all the other parameters constant. The shape and size of the fabricated microholes, machining time, actual material removal rate, non-Faradaic non-transient effect and the number of short circuits are considered as response factors. Experimental results confirm that the material removal rate and machining time, respectively, increases and decreases with an increase in the electrolyte temperature. It is also observed that both the side gap ratio and the taper angle increase with the electrolyte temperature.

The Effect of Electrolyte Temperature on the Electrodeposition of Cuprous Oxide Films

The Effect of Electrolyte Temperature on the Electrodeposition of Cuprous Oxide Films

Effect of electrolyte temperature on Faradaic effect in electrochemical microdrilling

Effect of electrolyte temperature on Faradaic effect in electrochemical microdrilling

Effect of electrolyte temperature on porous electrodeposited copper for pool boiling enhancement

Micro/nanostructured grains were grown on copper surface by electrodeposition method in various electrolyte temperatures to investigate the saturated pool boiling enhancement of distilled water in atmospheric pressure. Microstructure, surface topography, and wickability of surfaces were investigated. The SEM images show open and interconnected porous surfaces covered by micro grains with different sizes. As the electrolyte temperature increases, the grain shape changes from rounded to angular, the connection between grain cluster and the capillary performance improves, and the mechanical stability increases. The experimental results of pool boiling heat transfer on porous surfaces indicated that the critical heat flux (CHF) increased with surface capillarity performance and it was compatible with prediction of gain heat flux. The room temperature electrodeposited porous surfaces shows the highest CHF and heat transfer coefficient (HTC) of the 140W/cm2 and 19.1W/cm2K, respectively which is 60% and 200% higher than that of plain surface.

Optimization of packed bed electrolysis of zinc anode casing of spent dry cell batteries

In this research work, statistical analysis and optimization of the production of electrolytic zinc powder from zinc anode casing of spent dry cell batteries by packed bed electrolysis technique were carried out using response surface methodology (RSM). The analysis considered the effect of electrolyte temperature (30–50°C), stirring rate (250–350rpm), and current density (500–1000A/m2) on the cathodic current efficiency, anodic current efficiency, specific energy demand, and powder productivity. The experimental design was based on Box-Behnken design using quadratic polynomial equations for predicting the mathematical models. The results indicate that the proposed models predict the responses adequately within the limits of the packed bed electrolysis process parameters being used. The current density, the second order effect of both current density and stirring rate, and the two level interactions of temperature and current density are the most significant model terms associated with cathodic current efficiency. It was also found that, RSM can be considered as a powerful tool in the optimization of packed bed electrolysis.

Effect of ZnO Layers on Transport and Relaxation of Charge in Porous Silicon–Silicon Structures

Zinc oxide nanostructures have been grown by electrochemical deposition on porous silicon-silicon substrate. The effect of electrolyte temperature on the morphology of grown ZnO arrays was observed. Temperature dependencies of the electrical conductivity for the structures based on porous silicon were investigated in 80-325 K range. The results are analyzed within the model of disordered semiconductors and the activation energy of charge transport is determined. It is shown that ZnO layers cause the decrease of the electrical conductivity activation energy in 140-250 К temperature range. Electric conductivity was also shown to be dependent on the morphology of ZnO arrays. Based on the spectra of thermally stimulated depolarization current, the localized electron states in the experimental samples are found. The trap levels are distributed quasi-continuously on the activation energy and exist in the ranges of 0.2-0.3, 0.4-0.45, 0.5-0.55 and 0.6-0.65 eV. ZnO nanocrystals grown on porous silicon substrates modify density of states in different energy ranges.

The effect of anodization temperature on optical properties of nanoporous anodic alumina (NAA) films

Nanoporous anodic alumina (NAA), produced by aluminum anodization presents interesting optical effects in luminescence property exhibiting waveguides or Fabry–Pérot interference. This phenomenon, which is used as transducer response in optical sensors, depends on morphological characteristics of the NAA films, such as pore diameter, inter-pore distance and film thickness. In this work, the effect of electrolyte temperature on NAA morphology was investigated and, consequently, how this effect shaped the interference property. For this, all anodizing experimental conditions were kept constant while the electrolyte temperature was changed (5, 10, 15, 20 and 25°C). It was observed an increase in the minimum and stationary current density values during anodization as the electrolyte temperature increased, which were correlated to enlargement of porous oxide layer, since pore diameter, inter-pores distance and porosity remained constant for all studied temperatures. The photoluminescence (PL) spectra showed an increase in the number of fringes and an amplitude decrease with the increase of electrolyte temperature. NAA film thickness was evaluated using optical and morphological parameters and compared to values in the literature. A brief discussion of the results regarding the ratio of film thickness and pore diameter (L/dp) was performed to validate the NAA films with better waveguides property to be used as a platform for optical sensing applications.

Effect of electrolyte temperature on the formation of highly ordered nanoporous alumina template

In this work, we present a systematic influence of electrolyte temperature along with anodizing potential on the pore parameters during two-step anodization of Al in H2SO4 electrolyte. Top surface morphology of the nanoporous templates was examined with the help of field emission scanning electron microscope and atomic force microscope. Three-dimensional (3D) Fast Fourier Transform (FFT) image analysis was then employed to quantify pore regularity and pore periodicity as a function of both the bath temperature (1–15 °C) and the anodic potential (15–25 V). A highest pore regularity ratio of 5 × 108 was obtained at 3 °C and 25 V with a pore diameter of 32 ± 3 nm and inter-pore distance of 65 nm. With further increase in temperature, the pore regularity ratio was found to decrease drastically. It was found that higher temperature favored the dissolution of compact aluminum oxide layer isotropically along the pore length. This process in effect enhanced the pore size, growth rate, and template top surface roughness without affecting much inter-pore distance. Self-ordering of the pores was found to improve with increasing anodizing potential with a critical influence of the current density along with inter-pore distance. The mechanism of pore growth was discussed in terms of temperature-dependent activation energy controlled dissolution of aluminum. The typical activation energy evaluated at 25 V was 72.8 kJ/mol at 3 °C.

Nickel-Cerium Alloys for Borohydride Oxidation

Nickel and nickel-cerium (Ni-Ce) alloys with different amounts of Ce (5 and 10 at.% Ce) have been prepared by arc melting and characterized by scanning electron microscopy and electron probe microanalysis based on energy dispersive X-ray spectroscopy, to investigate microstructure and to determine phase composition. Subsequently, Ni and Ni alloy-based electrodes were fabricated and studied for borohydride (BH4 -) oxidation in alkaline media by cyclic voltammetry and chronoamperometry in the temperature range 25 – 45 ºC. Preliminary results showed comparable BH4 - oxidation peak current densities obtained at three electrodes, with Ni95Ce5 electrode giving the highest current densities. Electrochemical data are modelled to obtain relevant kinetic parameters of BH4 - oxidation at these electrodes. Effect of electrolyte temperature on the evaluated parameters has been investigated as well.

Effect of electrolyte temperature on the pseudo-capacitive behavior of manganese oxide in N-butyl-N-methylpyrrolidinium–dicyanamide ionic liquid

The electrochemical behavior of anodically deposited Mn oxide in N-butyl-N-methylpyrrolidinium–dicyanamide (BMP–DCA) ionic liquid (IL) at various temperatures (30–80 °C) is investigated. Cyclic voltammetry (CV) is used to evaluate the electrochemical performance of the Mn oxide. Surface morphology of the deposited oxide after charging/discharging is examined by scanning electron microscopy (SEM). The experimental data show that the Mn oxide electrode exhibits good pseudo-capacitance performance even at 80 °C. In the ionic liquid studied, the specific capacitance increases with increasing BMP–DCA IL temperature. A specific capacitance of 93 F g−1 in a potential window of 3 V is obtained at 80 °C, which is about 50% higher than that obtained at 30 °C. The experimental results also show that the capacitance-retained ratio of the oxide electrode increases with increasing temperature at a high potential sweep rate. Furthermore, the capacitance decline about 40% after 500 repeated charging/discharging cycles in BMP–DCA IL at 80 °C is observed, which is better than that measured in an aqueous electrolyte.