Electrochemical Behavior and Electrodeposition of Sn Coating from Choline Chloride–Urea Deep Eutectic Solvents

Round 1

Reviewer 1 Report

This work describes an interesting study on the electrodeposition of Sn from a deep eutectic solvent solution. Such method is promising considering the electrolyte stability during the deposition process, its high conductivity and stability from the thermal and electrochemical point of views. Authors studied the deposition process by cyclic voltammetry under different conditions. Varying the scan rate, process temperature and salt concentration allowed to understand the deposition mechanisms, well confirmed by theoretical models and post-experiment characterization.

The context is well described with a comprehensive introductory part and the materials and methods section is adequately presented. Also, results are convincing and properly discussed.

Based on such comments, I would recommend the publication of this work, however some improvements are suggested to increase the quality of the manuscript:

• In general: a re-reading of the text should be made to correct typos
• Company names and locations should be provided together with the reagents and instruments
• In Materials and Methods section, should be better explained the aim and differences between experiments using W and Cu working electrodes. Otherwise it becomes clear only reaching the section 3.3, but I think it would be clearer to anticipate the description in the dedicated experimental section.
• In Materials and Methods section, it would be appreciated some more details about the Cu working electrode geometry. Is it a flat sample? Square or disk shaped? Additionally, when using the W wire electrode, was the immersion length controlled or somehow quantified?

Author Response

Special thanks to you for your good comments. 

Please see the attachment for the revised paper.

Author Response File: Author Response.doc

Reviewer 2 Report

There are some corrections to be made in this manuscript:

Rows 77-78

The description of the kind of used equipment of SEM and XRD should be given.

The applied SEM working parameters should be added i.e. acceleration voltage, working distance, the type of image (SEI or BEI). The type of anode in case of XRD should be given. In addition, you can specify the type software you have used.

3.3. Microstructure and morphology of Sn coating – I suggest changing the name of this subsection. The current name indicates that the microstructure will be shown on the cross-section of the coatings. While only the surface topography is shown.  

Figure 6 - All diffraction peaks should be described.

Figure 7 - The type of image, e.g. SEI, BEI should be in the caption of the figure. The maker bars in all pictures should be legible.

Conclusions could be more detailed.

If these suggestions are taken into account, I will consider this article again.

Author Response

Special thanks to you for your good comments. 

Please see the attachment for the revised paper.

Author Response File: Author Response.pdf

Reviewer 3 Report

The authors of this study present some interesting results from the field of: Electrochemical Behavior and Electrodeposition of Sn Coating from Choline Chloride-Urea Deep Eutectic Solvents with accent on the first part (electrochemical behavior) and some promising results, but insufficiently argued, in the second part (electrodeposition). 

Few comments must be taken in consideration in order to improve the quality of the article: 

L(line)31: remove the space after the comma 

L36: in the 

L40: as - are 

L65: SnCl2 powders

L75: The films were .... 

L81-82: please present clearly what is the electrolyte solution 

L98: put a verb in the phrase The minimum ....

L106: formular - formula 

L139: what is 100 mV/s a scan rate ? 

L179: Eqs. (1) and (2) are probable (3) and (4) 

L195: It can be ..... must be rephrase 

 L199: which sample from figure 7 was analyzed ?, the presence of the substrate is not desired in case of a good coating layer , how thick is the new Sn layer ? 

L222 : the scale of main images is to small , make it visible, mention the magnification power 

The Sn layer can be considered a coating in the first three cases (a), b) and c) from figure 7) , also uncovered spaces are observed in 7 d) image . 

This technique needs improvements in order to be considered a valuable coating method in this material case. So your conclusions for this subject must be referred as further work or perspectives. 

Main correction: check the references 2 and 24 - are the same so you must reconsider the references section - lack of concentration and attention of the authors 

 

 

 

 

 

 

 

Author Response

Special thanks to you for your good comments. 

Please see the attachment for the revised paper.

Author Response File: Author Response.pdf

Reviewer 4 Report

Dear Authors,

I had oportunity to review your paper titled "Electrochemical Behavior and Electrodeposition of Sn Coating from Choline Chloride-Urea Deep Eutectic Solvents".

I have read the manuscript carefully and I have some comments and suggestions, which have been listed below.

General remarks:

• Please check your keywords, they should be in the same style. Now, first started by capital letter, other not. I propose to add some keyords, which allow to increase visibility of future paper.
• You have presented 39 references. However, none of them has been published in last three years. In my opinion this is unacceptable. Please add some of the latest papers to the references. You should sho the novelty of your work. It is hard to show novelty without new papers as scientific background.
• Ref. 16, 23, 27-29 - the date should be bolded.
• I propose to add some values from investigations to abstract.
• In many places double spaces can be found.

Introduction:

• This part shuld be extended by information from latest three years.
• "At present, Sn, Cr, Zn, Co, Al, Cu, Ag, Sm, Ni have been electrodeposited in DESs-based electrolytes [11-18]." - this kind of citation (8 position in one bracket) is not proper. Please extend this part of your text.

Materials and Methods:

• Lines 62-5 - why these parameters have been used? The relevnt description should be in the text. Potential reader, who will not be expert in presented field, should know this information.
• How many specimens have you used? What were dimensions of specimens?
• How many measurements were taken?

Results and Discussion:

• This part is the strongest in your work. Results are clearly presented. Also, the scientific discussion is included. I have some minor remarks here:
• Fig. 7 - I propose to add scale bars. It will be more clear than value of magn. in the name of the figure.

Conclusions:

• I propose to mark the most important conclusions in the points (1., 2., etc.)
• Please support conslusions with values.

Author Response

Special thanks to you for your good comments. 

Please see the attachment for the revised paper.

Author Response File: Author Response.doc

Round 2

Reviewer 2 Report

I accept in present form

Reviewer 3 Report

For publish