Influence of Surface Pretreatments on the Anticorrosion of Polypyrrole Electro-Polymerized Coatings for Copper in Artificial Seawater

Round 1

Reviewer 1 Report

The presented work is devoted to a relevant topic and is performed at a fairly high level. I have a few notes:
1. In the abstract and further in the text of the manuscript, the abbreviation PPy is used, but there is no transcript.
2. In line 165, instead of mHz, it should probably be MHz.
3. Would like to see a more detailed description of the plasma treatment process. What type of discharge was used, what are the current and voltage parameters?
I recommend this manuscript for publication in the journal Metals after the above remarks have been corrected.

Author Response

Reviewer #1

The presented work is devoted to a relevant topic and is performed at a fairly high level. I have a few notes:

1. In the abstract and further in the text of the manuscript, the abbreviation PPy is used, but there is no transcript.

Response: Initially, we quite appreciate your approve on our work. It was our negligence for leaving out the definition of PPy, which had been provided it in the revised manuscript. Thank you for the reminding.

 

2. In line 165, instead of mHz, it should probably be MHz.

Response: Thanks for this comment. The frequency used in EIS measurements ranged from 10⁵ to 10^-2 Hz, i.e., 100 kHz to 10 mHz. Anyway, the expression in our manuscript was confused for readers, and we have modified it as “10⁵ to 10^-2 Hz”.

 

3. Would like to see a more detailed description of the plasma treatment process. What type of discharge was used, what are the current and voltage parameters?

Response: Thanks a lot for your reminding. We explored the instruction of the utilized apparatus, and found that the discharging condition employed in this study was equivalent to a voltage of 8 kV. However, the discharging current is hardly detected due to the dependence on real-time vacuum degree. The related parameters have been supplied in the revised manuscript (yellow-highlighted), please kindly refer to it.

 

I recommend this manuscript for publication in the journal Metals after the above remarks have been corrected.

Reviewer 2 Report

This paper deals on plasma treatments of copper surfaces for the subsequent electropolymerization of polypyrrole (PPy) coatings aimed at improving anticorrosion performances against artificial seawater. The target systems and processes are characterized by SEM, IR and electrochemical techniques including LSV, EFM, and EIS. Some theoretical data are also presented and discussed.

Generally speaking, the paper is exceedingly long-winded and full of observations not adequately prove. As a matter of fact, the manuscript presents many problems/drawbacks, that make it definitely unacceptable for publication. The main reasons for this decision are summarized in the following list:

1. The whole paper text should have been revised line-by-line with the aid of a native English speaker, to polish the language, remove unusual constructions and clarify various observations. Some sentences (see for instance the one reported in lines 382-383) are completely obscure and unsupported.
2. The authors should have carried out tests even in real seawater, and not only in artificial one, to demonstrate the applicability of the developed materials under real-world conditions.
3. Section 2.3 is incredibly poor in terms of details regarding the operating conditions used for the different analytical characterizations.
4. Scheme 1 is eye-catching but almost useless. In Scheme 1, as well as in other parts of the paper (see for instance data reported in Tables 2 and 3 and Figures 6e-f), the authors present numerical data with a very high number of significant figures, indicating that they do not have a sound grasp of the topic.
5. The paper completely lacks of XPS analyses as a function of the adopted processing conditions, which would have been of utmost importance to clarify the elements present in the targeted specimens and their actual oxidation states, shedding thus an important light into the used process.
6. The choice of the indicated crystallographic planes for MD simulations is groundless and completely unjustified in the absence of XRD and TEM analyses – the latter would have been of utmost importance to clarify the exposed facets. This seriously undermines the applicability of all MD results to the present case study.
7. The superimposition of many overlapped curves in Figs. 1, 3b and 3c does not enable to clearly observe the real differences occurring between the various cases.
8. SEM images in Figs. 2 and 6 are of a too low magnification to enable a really meaningful insight into the system morphology and organization at the nano-scale.
9. IR spectra in Fig. 2 are of a very suspicious shape, highlighting the occurrence of technical problems which have been neglected by the authors.
10. The authors investigate material wettability properties, which, as they should know, are strongly dependent on the system surface roughness – unfortunately, AFM analyses, which would have enabled an evaluation of surface roughness as a function of the adopted processing conditions, are missing.
11. The discussion of EIS data is long-winded, often unclear and unconvincing, and not properly supported by adequate experimental results.
12. 5 is badly prepared and confusing.
13. The graphical layout of Figures 5c-d is unsuitable for a scientific paper.
14. The Conclusions are badly organized, not adequately supported by the data, and no future perspectives for the prosecution of the presented research activities can indeed be foreseen.

I could go on further, but I think it is more than enough to stop here. I recommend the immediate paper rejection.

Author Response

Due to the diplayed figures, Please kindly find the point-by-point responses in the attachment. Thank you very much!

Author Response File: Author Response.pdf

Reviewer 3 Report

Paper : Influence of surface pretreatments on the anticorrosion of polypyrrole electro-polymerized coatings for copper in artificial seawater present some interesting results in the field of metallic materials corrosion and non-metallic thin layers. Few minor corrections can help to improve the article. 

L13: explain PPy

L453: explanation for figures e) and f) or mentions must be insert at figure 6 presentation 

• in second EDS spectra what are the unidentified peaks between 2 and 3 keV ? are to big to be noise .
• the values of wt% percentages are average values from more than 1 area?- usually EDS is considered a semi-quantitative technique  please provide a St Dev for this values (for Cu, O, N and C chemical elements wt%) 
• re-structure the conclusions focusing also on experimental results 

The article present many experimental results well performed and analyzed. 

•  

Author Response

Reviewer #3

Paper: Influence of surface pretreatments on the anticorrosion of polypyrrole electro-polymerized coatings for copper in artificial seawater present some interesting results in the field of metallic materials corrosion and non-metallic thin layers. Few minor corrections can help to improve the article. 

1. L13: explain PPy

Response: Thank you for this reminding. Similar as the response for Comment 1 of Reviewer #1, we have defined the item “PPy” in L13.

 

2. L453: explanation for figures e) and f) or mentions must be insert at figure 6 presentation 

Response: We highly agree with this suggestion. The explanation has been supplemented in the caption of Figure 6.

• in second EDS spectra what are the unidentified peaks between 2 and 3 keV? are to big to be noise.

Response: Thanks a lot for your reminding. We have reorganized the EDS results to explicitly present the elemental analysis on different copper surface. The peaks between 2 and 3 keV are mainly assigned to S, Cl and K elements resulting from the incorporation of dissolved salts in ASW. It can be seen in Figure 6d that d-PPy coating is tolerant and robust during long-term immersion in ASW. Hence, in-situ ions inevitably penetrated inward the coating, and thereby emerged the relevant signals in EDS spectrum. In addition, we have made the interpretation on these elements in the revised manuscript (yellow-highlighted). Please kindly refer to it.

• the values of wt% percentages are average values from more than 1 area? - usually EDS is considered a semi-quantitative technique, please provide a St Dev for these values (for Cu, O, N and C chemical elements wt%).

Response: Thank you for this question. In the practical experiments, three similar areas were framed for EDS spectra, and the reported results in Figure 6 were the mean values. Indeed, the standard deviations are significative for readers to better understand the presented outcomes, which have been added into the inset tables of Figure 6e and 6f.

 

3. Re-structure the conclusions focusing also on experimental results 

Response: Thank you very much for this suggestion. The conclusions have been re-organized and focused more on the experimental observations. Please refer to our revised manuscript.

 

The article presents many experimental results well performed and analyzed. 

Author Response File: Author Response.pdf