Rapid Electrodeposition and Corrosion Behavior of Zn Coating from a Designed Deep Eutectic Solvent
and Jiangping Tu 1,2
Round 1
Reviewer 1 Report
The authors reported a deep eutectic solvent containing a high concentration of zinc ions as an electrolyte to improve the electrodeposition rate for zinc plating. The submission required major revision before acceptance taking into account the following points:-
1. The title should be revised to be clear and informative. It should reflect the author’s main findings.
2. An application should be added.
3. Some of the Figures can be moved to an Electronic supporting file.
4. Conclusions should be rewritten. Remove numbering and write the conclusion as a paragraph.
5. References should be updated including these References; https://doi.org/10.1016/j.cej.2022.136614; https://doi.org/10.1016/j.jma.2020.12.005; https://doi.org/10.1021/acsenergylett.1c00608
6. A comparison with previously published methods should be discussed and summarized in a table.
7. The language should be revised and typos should be corrected.
Author Response
Point 1: The title should be revised to be clear and informative. It should reflect the author’s main findings.
Response 1: Thanks to your suggestion, we have redrafted the title.
Point 2: An application should be added.
Response 2: The application of our research has been added at the end of the article.
Point 3: Some of the Figures can be moved to an Electronic supporting file.
Response 3: We have put the first Figure in the support information. We consider that putting the rest Figures in the paper text may be more convenient for readers to consult.
Point 4: Conclusions should be rewritten. Remove numbering and write the conclusion as a paragraph.
Response 4: We have modified the conclusion part carefully.
Point 5: References should be updated including these References;
https://doi.org/10.1016/j.cej.2022.136614; https://doi.org/10.1016/j.jma.2020.12.005;
https://doi.org/10.1021/acsenergylett.1c00608
Response 5: Thank you for your recommendation. We have quoted the references you recommended.
Point 6: A comparison with previously published methods should be discussed and summarized in a table.
Response 6: The comparison between this work and previous work has been placed in Table S1.
Point 7: The language should be revised and typos should be corrected.
Response 7: We have carefully reviewed and revised our manuscript to correct the grammatical mistakes and improve readability.
Reviewer 2 Report
This work suggests the process of metal zinc electrodeposition using a deep eutectic solvent containing high concentrations of zinc(II) ions. The highlight of the study is the combination of two different types of deep eutectic solvent: mixtures of choline chloride with ethylene glycol and urea. A study of the voltammetric behavior of the system has been carried out. The effect of electrochemical deposition conditions on the surface morphology, microstructure, and corrosion resistance of metallic zinc coatings has been established. In my opinion, the manuscript can be recommended for publication in Metals after a minor revision. My suggestions and comments are the following.
1. Cyclic voltammetry behavior was studied at a scan rate of 5 mV·s–1. Why was this potential scanning rate chosen? Did the influence of diffusion restrictions be reflected at such a sweep rate? How did the sweep rate affect the appearance of the voltammograms? As far as I understand, at such a relatively low sweep rate, the recorded voltammograms can be considered quasi-stationary in the first approximation. However, the authors do not report anything about this issue.
2. Registered current density vs. potential curves at different temperatures are raw experimental data. It is customary to process these data in Arrhenius-like coordinates to determine activation energies. It is the activation energy (together with the pre-exponential factor) that is the quantity that correctly reflects the temperature dependences of the rates of various physicochemical processes. Please carry out the appropriate processing of the experimental data and try to calculate the activation energies. The method for calculating the apparent activation energy at a constant potential measured relative to an arbitrary reference electrode can be found, for example, in the study doi: 10.1016/j.jelechem.2010.12.014. The use of this technique to determine the activation energy in DES-based electrolytes during metal precipitation is described in study doi: 10.1016/j.electacta.2017.05.144.
3. It would be necessary to compare the data obtained in this work with the results given in the literature. In particular, it would be interesting to compare the properties and characteristics of coatings deposited from DES-based plating baths with those of zinc coatings produced in aqueous electrolytes.
Author Response
Point 1: Cyclic voltammetry behavior was studied at a scan rate of 5 mV·s–1. Why was this potential scanning rate chosen? Did the influence of diffusion restrictions be reflected at such a sweep rate? How did the sweep rate affect the appearance of the voltammograms? As far as I understand, at such a relatively low sweep rate, the recorded voltammograms can be considered quasi-stationary in the first approximation. However, the authors do not report anything about this issue.
Response 1: At a relatively low scanning rate, the effect of diffusion mass transfer and the shift of redox peak are small. Just as the reviewer considers, at such a relatively low sweep rate, the recorded voltammograms can be considered quasi-stationary in the first approximation, which will more accurately reflect the characteristics of the reaction itself. We have added these explanations to chapter 2.2.
Point 2: Registered current density vs. potential curves at different temperatures are raw experimental data. It is customary to process these data in Arrhenius-like coordinates to determine activation energies. It is the activation energy (together with the pre-exponential factor) that is the quantity that correctly reflects the temperature dependences of the rates of various physicochemical processes. Please carry out the appropriate processing of the experimental data and try to calculate the activation energies. The method for calculating the apparent activation energy at a constant potential measured relative to an arbitrary reference electrode can be found, for example, in the study doi: 10.1016/j.jelechem.2010.12.014. The use of this technique to determine the activation energy in DES-based electrolytes during metal precipitation is described in study doi: 10.1016/j.electacta.2017.05.144.
Response 2: Thank you for your reminder and the references you recommended. The references are very helpful to determine the activation energy in DES-based electrolytes during metal precipitation. We read the references carefully and found that the proposed method might be not reliable for our case. As demonstrated in the study doi: 10.1016/j.electacta.2017.05.144, the values of electrode potentials were chosen in the initial section of the voltammetric peak where the electrochemical reaction was controlled by the charge transfer. However, no obvious voltammetric peak was found in our case as shown in Figure 2, which may be related to the special electrolyte with high concent of metal ions. The present study aims to demonstrate the avaliability of the novel electrolyte for the depostion of Zn coating with high deposition rate. The corresponding mechanism of the deposition will be investigated in details in our following studies and the recommended method in this comment must be useful to our future studies.
Point 3: It would be necessary to compare the data obtained in this work with the results given in the literature. In particular, it would be interesting to compare the properties and characteristics of coatings deposited from DES-based plating baths with those of zinc coatings produced in aqueous electrolytes.
Response 3: The comparison between this work and previous work has been placed in Table S1. We are sorry that we did not compare the properties and characteristics of the coating deposited in DES based bath with those of the zinc coating produced in aqueous electrolyte. Since DES electrolyte and aqueous electrolyte are two different systems, the comparison between them has little reference significance. Our work focuses on improving the electrodeposition rate of DES. Therefore, we only compare the difference of electrodeposition rate.
Reviewer 3 Report
The paper is topical for larger target groups being about corrosion aspects of an electrodeposited Zn coating from from a deep eutectic solvent with high zinc ion concentration. The paper has a suitable title and abstract introducing the manuscript aim and is clearly written and well organized.
In order to be published there are some things to be completed taking into account the following
a) the original character needs to be better sustained
b) the subchapter 2.1 entitled Characterization without other details has to be completed c) the research design has to be completed as well ( AFM or XPS is going to introduce more information )
d) introducing the kinetic law to compute activation energy will permit discussion of temperature influence in a more quantified way
e) some statistical treatment of data could be performed
f) polarization resistance in evaluation of porosity will enrich the discussion
Author Response
Point 1: The original character needs to be better sustained.
Response 1: We have carefully reviewed and revised our manuscript to correct the grammatical mistakes and improve readability.
Point 2: The subchapter 2.1 entitled Characterization without other details has to be completed.
Response 2: We have made a supplementary description of all the characterization methods.
Point 3: The research design has to be completed as well ( AFM or XPS is going to introduce more information )
Response 3: We understand that AFM may better reveal the surface roughness of zinc coating. However, in the present study, we mainly focused on the improvement of DES electrodeposition rate, and we think that the SEM images may not be optimal, but should be sufficient to show the difference in surface roughness of the coating.
Point 4: Introducing the kinetic law to compute activation energy will permit discussion of temperature influence in a more quantified way.
Response 4: Thank you for your suggestion. As recommended by Reviwer 2, the method for calculating the apparent activation energy at a constant potential measured relative to an arbitrary reference electrode may be helpful to study the activation energy. The values of electrode potentials should be chosen in the initial section of the voltammetric peak where the electrochemical reaction was controlled by the charge transfer. However, no obvious voltammetric peak was found in our case as shown in Figure 2, which may be related to the special electrolyte with high concent of metal ions. The present study aims to demonstrate the avaliability of the novel electrolyte for the depostion of Zn coating with high deposition rate. The corresponding mechanism of the deposition and activation energy will be investigated in details in our following studies.
Point 5: Some statistical treatment of data could be performed.
Response 5: We have processed the experimental data.
Point 6: Polarization resistance in evaluation of porosity will enrich the discussion.
Response 6: Thanks for your suggestion. We added the discussion on the influence of porosity on polarization resistance in chapter 3.4.1.
Round 2
Reviewer 1 Report
The authors addressed most of the comments and the revised version can be accepted.
Reviewer 3 Report
The authors affirmed in their response that a part of my suggestion to be developed in this manuscript are going to be treated in a future one. It is not what I do believe, but generally I do recognize that the revised form was significantly impreoved and could be published as it is
