scholarly journals The ionic equilibrium in the CuSO4-H2SO4-H2O system and the formation of the honeycomb-like structure during copper electrodeposition

2008 ◽  
Vol 73 (7) ◽  
pp. 753-760 ◽  
Author(s):  
Nebojsa Nikolic ◽  
Ljubica Pavlovic ◽  
Goran Brankovic ◽  
Miomir Pavlovic ◽  
Konstantin Popov
Keyword(s):  
Hydrogen Evolution ◽  
Current Density ◽  
Diffusion Current ◽  
Copper Electrodeposition ◽  
Hydrodynamic Conditions ◽  
Ionic Equilibrium ◽  
Electrode Layer ◽  
Limiting Diffusion Current

The ionic equilibrium of the species in the CuSO4-H2SO4-H2O system was employed to systematize the conditions of copper electrodeposition leading to the formation of the honeycomb-like structure. The reason why CuSO4 concentrations higher than 0.15 M are unsuitable for the formation of honeycomb-like structures is shown. The range of H2SO4 concentrations enabling the formation of this type of structure was also determined. The conditions leading to the formation of the honeycomb-like structures are: electrodeposition from solutions with lower concentrations of Cu(II) ions (0.15 M CuSO4 and less) in a concentration range from 0.25 to 1.0 M H2SO4, at a temperature of 18.0?1.0 ?C and at overpotentials outside the plateau of the limiting diffusion current density at which hydrogen evolution is vigorous enough to change the hydrodynamic conditions in the near-electrode layer. .

scholarly journals Comparative analysis of the polarization and morphological characteristics of electrochemically produced powder forms of the intermediate metals

2014 ◽  
Vol 33 (2) ◽  
pp. 169 ◽  
Author(s):  
Nebojsa D. Nikolic ◽  
Predrag M. Zivkovic ◽  
Bojan Jokic ◽  
Miomir G. Pavlovic ◽  
Jasmina S. Stevanovic
Keyword(s):  
Surface Morphology ◽  
Current Density ◽  
Morphological Characteristics ◽  
Copper Surface ◽  
Diffusion Current ◽  
Copper Electrodeposition ◽  
Continuous Change ◽  
Polarization Characteristics ◽  
High Overpotentials ◽  
Limiting Diffusion Current

The polarization and morphological characteristics of powder forms of the group of the intermediate metals were examined by the analysis of silver and copper electrodeposition processes at high overpotentials. The pine-like dendrites constructed from the corncob-like forms, very similar to each others, were obtained by electrodeposition of these metals at the overpotential belonging to the plateaus of the limiting diffusion current density. The completely different situation was observed by electrodeposition of silver and copper at the overpotential outside the plateaus of the limiting diffusion current density in the zone of the fast increase of the current density with the overpotential. The silver dendrites, very similar to silver and copper dendrites obtained inside the plateaus of the limiting diffusion current density, were obtained at the overpotential outside the plateau. Due to the lower overpotential for hydrogen evolution for copper, hydrogen produced during copper electrodeposition process strongly affected the surface morphology of copper. The same shape of the polarization curves with the completely different surface morphology of Cu and Ag electrodeposited at overpotentials after the inflection point clearly indicates on the importance of morphological analysis in the investigation of polarization characteristics of the electrodeposition systems. Role of hydrogen as crucial parameter in the continuous change of copper surface morphology from dendrites to the honeycomb-like structures was investigated in detail. On the basis of this analysis, the transitional character of the intermediate metals between the normal and inert metals was considered. The typical powder forms characterizing electrodeposition of the intermediate metals were also defined and systematized.

scholarly journals Estimation of the exchange current density and comparative analysis of morphology of electrochemically produced lead and zinc deposits

2017 ◽  
Vol 82 (5) ◽  
pp. 539-550
Author(s):  
Nebojsa Nikolic ◽  
Predrag Zivkovic ◽  
Goran Brankovic ◽  
Miomir Pavlovic
Keyword(s):  
Current Density ◽  
Exchange Current ◽  
Exchange Current Density ◽  
Diffusion Current ◽  
Electron Microscopic ◽  
Zinc Electrodeposition ◽  
Lead And Zinc ◽  
Current Densities ◽  
Limiting Diffusion Current ◽  
Zinc Deposits

The processes of lead and zinc electrodeposition from the very dilute electrolytes were compared by the analysis of polarization characteristics and by the scanning electron microscopic (SEM) analysis of the morphology of the deposits obtained in the galvanostatic regime of electrolysis. The exchange current densities for lead and zinc were estimated by comparison of experimentally obtained polarization curves with the simulated ones obtained for the different the exchange current density to the limiting diffusion current density ratios. Using this way for the estimation of the exchange current density, it is shown that the exchange current density for Pb was more than 1300 times higher than the one for Zn. In this way, it is confirmed that the Pb electrodeposition processes are considerably faster than the Zn electrodeposition processes. The difference in the rate of electrochemical processes was confirmed by a comparison of morphologies of lead and zinc deposits obtained at current densities which corresponded to 0.25 and 0.50 values of the limiting diffusion current densities.

scholarly journals Copper deposits obtained by pulsating overpotential regime with a long pause and pulse duration from sulfated solutions

2020 ◽  
Vol 85 (6) ◽  
pp. 795-807
Author(s):  
Fatemeh Shafiei ◽  
Kourosh Jafarzadeh ◽  
Ali Madram
Keyword(s):  
Current Density ◽  
Sem Analysis ◽  
Diffusion Current ◽  
Electron Microscopic ◽  
Copper Deposits ◽  
H2so4 Concentration ◽  
Scanning Electron Microscopic ◽  
Polarization Characteristics ◽  
Pulsating Overpotential ◽  
Limiting Diffusion Current

The morphologies of the copper deposits obtained by pulsating overpotential regime with prolonged pulse and pause durations from the solution of 0.15 M CuSO4 in 0.50 M H2SO4 at overpotentials lower, higher and belonging to the plateau of limiting diffusion current density were compared with those obtained by the same electrodeposition regime from solutions of 0.075 and 0.30 M CuSO4 in 0.50 M H2SO4 and 0.15 M CuSO4 in 0.25 and 1.00 M H2SO4 at overpotentials outside the plateau of limiting diffusion current density. These samples were characterized by scanning electron microscopic (SEM) analysis and the cathodic polarization characteristics from solutions compared. Increasing the Cu(II) concentration led to an increase in the limiting diffusion current density. Decreasing the H2SO4 concentration shifts both beginning and the end of the plateau of the limiting diffusion current density towards higher electrodeposition overpotentials. Also, electrodeposition in solutions of 0.15 M CuSO4 in 0.25 and 1.00 M H2SO4 led to the formation of morphological forms of copper deposits characteristic for electrodeposition of copper from higher CuSO4 or lower H2SO4 in solution at some higher overpotentials.

scholarly journals Effect of temperature on the electrodeposition of disperse copper deposits

2007 ◽  
Vol 72 (12) ◽  
pp. 1369-1381 ◽  
Author(s):  
Nebojsa Nikolic ◽  
Ljubica Pavlovic ◽  
Miomir Pavlovic ◽  
Konstantin Popov
Keyword(s):  
Current Density ◽  
Sem Analysis ◽  
Diffusion Current ◽  
Effect Of Temperature ◽  
Electron Microscopic ◽  
Copper Deposits ◽  
Disperse Copper ◽  
Average Current ◽  
Limiting Diffusion Current

The effect of temperature on the electrodeposition of copper at overpotentials belonging to the plateau of the limiting diffusion current density and higher was examined by the determination of the average current efficiency of hydrogen evolution and by scanning electron microscopic (SEM) analysis of the morphology of the formed copper deposits. Increasing the temperature of the solution led to a shift of both the beginning and the end of the plateau of the limiting diffusion current density towards lower electrodeposition overpotentials. Also, higher temperatures led to the formation of morphological forms of copper deposits characteristic for electrodeposition of copper at some higher overpotentials. The unexpected trend in the development of copper structures electrodeposited at an overpotential of 800 mV is discussed in terms of the effect of temperature on the viscosity and surface tension of the electroplating solution.

scholarly journals Relationship between cathodic protection current and limit diffusion current as an additional criteria of cathodic protection

2019 ◽  
pp. 23-31
Author(s):  
L. I. Nyrkova ◽  
S. O. Osadchuk ◽  
А. V. Klymenko ◽  
А. О. Rybakov ◽  
S. L. Melnychuk
Keyword(s):  
Oxygen Concentration ◽  
Current Density ◽  
Cathodic Protection ◽  
Diffusion Current ◽  
Effect Of Temperature ◽  
Electrochemical Characteristics ◽  
Time Data ◽  
Limit Diffusion Current ◽  
Effect Of Oxygen ◽  
Limiting Diffusion Current

The influence of the temperature and oxygen concentration in NS4 solution on the electrochemical characteristics of X70 steel for pipelines and the relationship of cathodic protection current density to limiting diffusion current density, in the normalized DSTU 4219 range of protective polarization potentials from -0.75 V to    -1.05 V (сh.s.е.) were investigated. It has been established that with increasing of the temperature from 20 to 80 °C, the corrosion activity of X70 steel increases, which is confirmed by more negative values of corrosion potential and an increasing of the corrosion rate, and indicates on the prevailing effect of temperature on the corrosion process compared to the effect of oxygen concentration. In the temperature range considered, the limiting diffusion current has a maximum value at 40 °C and decreases with increasing of temperature, correlating with a decreasing of the oxygen concentration. Under conditions of free oxygen access to the NS4 solution in the normalized DSTU 4219 range of protective polarization potentials, the ratio of cathodic protection to limiting diffusion  current varies from 0.4 to 1.3 at temperatures (20-40) oС, at temperatures (60-80) oC the ratio  is less than 1. Under conditions of limited oxygen access, the ratio  increases from 1.1 to 4.7. Using calculated and experimental results, it was shown that, at various values of relationship , conditions for excessive hydrogen evolution can be created, which represents a threat to the safe operation of the pipeline over time.  Data on the ratio values  should be taken into account when analyzing the protection state of pipelines.

A highly stable CoMo2S4/Ni3S2 heterojunction electrocatalyst for efficient hydrogen evolution

2021 ◽  
Author(s):  
Minmin Wang ◽  
Mengke Zhang ◽  
Wenwu Song ◽  
Weiting Zhong ◽  
Xunyue Wang ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Current Density ◽  
A Current

A CoMo2S4/Ni3S2 heterojunction is prepared with an overpotential of only 51 mV to drive a current density of 10 mA cm−2 in 1 M KOH solution and ∼100% of the potential remains in the ∼50 h chronopotentiometric curve at 10 mA cm−2.

scholarly journals Microwave-Assisted vs. Conventional Hydrothermal Synthesis of MoS2 Nanosheets: Application towards Hydrogen Evolution Reaction

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1040 ◽  
Author(s):  
Getachew Solomon ◽  
Raffaello Mazzaro ◽  
Vittorio Morandi ◽  
Isabella Concina ◽  
Alberto Vomiero
Keyword(s):  
Hydrothermal Synthesis ◽  
Hydrothermal Method ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Current Density ◽  
Crystal Morphology ◽  
Synthesis Method ◽  
Synthesis Methods ◽  
Mos2 Nanosheets ◽  
Microwave Assisted

Molybdenum sulfide (MoS2) has emerged as a promising catalyst for hydrogen evolution applications. The synthesis method mainly employed is a conventional hydrothermal method. This method requires a longer time compared to other methods such as microwave synthesis methods. There is a lack of comparison of the two synthesis methods in terms of crystal morphology and its electrochemical activities. In this work, MoS2 nanosheets are synthesized using both hydrothermal (HT-MoS2) and advanced microwave methods (MW-MoS2), their crystal morphology, and catalytical efficiency towards hydrogen evolution reaction (HER) were compared. MoS2 nanosheet is obtained using microwave-assisted synthesis in a very short time (30 min) compared to the 24 h hydrothermal synthesis method. Both methods produce thin and aggregated nanosheets. However, the nanosheets synthesized by the microwave method have a less crumpled structure and smoother edges compared to the hydrothermal method. The as-prepared nanosheets are tested and used as a catalyst for hydrogen evolution results in nearly similar electrocatalytic performance. Experimental results showed that: HT-MoS2 displays a current density of 10 mA/cm2 at overpotential (−280 mV) compared to MW-MoS2 which requires −320 mV to produce a similar current density, suggesting that the HT-MoS2 more active towards hydrogen evolutions reaction.

The passivity and overvoltage during hydrogen evolution and indium deposition of metallic indium

1977 ◽  
Vol 55 (10) ◽  
pp. 1710-1712 ◽  
Author(s):  
Alan N. Campbell
Keyword(s):  
Hydrogen Evolution ◽  
Current Density ◽  
Normal Manner ◽  
Tentative Explanation

The passivity and overvoltage during hydrogen evolution and indium deposition of metallic indium have been determined. Although the overvoltage to hydrogen evolution is fairly high and increases with current density in the normal manner, passivity to the solution of indium ions is almost completely absent, in contradistinction to aluminum, whose anodic passivity is complete. A tentative explanation is offered.

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