One-Step Method for Preparing Dispersive Tea Polyphenol/Graphene Nanosheets Enhanced with Anticorrosion Performance

Round 1

Reviewer 1 Report

Through the whole manuscript there are many parts highlighted in yellow (i.e. in the title and abstract). Are those remains from the previous submission? It should be corrected.

1. Line 60, "MoS2","2" should be subscript.

2. Line 65, it should be [27, 28]

3. Line 72, the ")." should be removed

4. Materials (Section 2.1.). Can the Authors provide more information about TP? Qualitative and quantitative composition of the purchased mixture would be very informative.

5. Line 116" It should be "λ", not "l".

6. Line 140: Instead of "to observe" it should be "to structurally characterize"

7. Figure 2a, the Authors discuss the 2teta at values higher than 20 degree, but in the Figure the 5-10 degree range is presented. This must be corrected.

8. Figure 3, I guess that those spectra were deconvoluted. However, there are no information about this processing in the text. Authors should described in details the process of deconvolution

9. Figure 3b, the C-N bonds? Where do the Nitrogen atoms come from? TP do not contain N, neither do graphite. It must be a mistake.

10. The structure of the obtained materials must be described in a more detailed way. I.e. it would be nice to know the ratio between the TP and graphene in the obtained product.

Author Response

Dear reviewer,

 Thank for your work to review my article and i have corrected the problem which you pointed out. i used the function of " track changes" in word. Please see the attachment.

1. Line 60, "MoS2","2" should be subscript.

Line 60, "MoS2","2"  has been corrected 

2. Line 65, it should be [27, 28]

Line 65, [27, 28] has been corrected 

3. Line 72, the ")." should be removed

Line 72, the ")." has been corrected 

4. Materials (Section 2.1.). Can the Authors provide more information about TP? Qualitative and quantitative composition of the purchased mixture would be very informative.

i downloaded relative information form website and wrote in section 2.1.   

5. Line 116" It should be "λ", not "l"  

has been corrected 

6. Line 140:" Instead of "to observe" it should be "to structurally characterize"

has been corrected 

7. Figure 2a, the Authors discuss the 2teta at values higher than 20 degree, but in the Figure the 5-10 degree range is presented. This must be corrected. 

i provide a new graphic of XRD which range from  5 to 40 degree.

8. Figure 3, I guess that those spectra were deconvoluted. However, there are no information about this processing in the text. Authors should described in details the process of deconvolution.

XPS peak 41 was adopted to deconvolute

9. Figure 3b, the C-N bonds? Where do the Nitrogen atoms come from? TP do not contain N, neither do graphite. It must be a mistake.

i'm sorry that i made a mistake in the Fig 3 and i have corrected it. 

10. The structure of the obtained materials must be described in a more detailed way. I.e. it would be nice to know the ratio between the TP and graphene in the obtained product.

The ratio is 1:1 (TP:GE) in the obtained product 

Reviewer 2 Report

In this paper, the authors prepared tea polyphenol/graphene nanosheets where tea polyphenols (TP) were employed as reducing and functionalization reagents. The functionalization and reduction of graphene are not clearly explained in the manuscript. Also, the manuscript is poor in terms of English writing. For this reason, it needs a major revision. Some of my comments are as follows:

1. Avoid abbreviations in the title.

2. Page 93, what did the authors use: graphene powder or graphite powder?

3. The schematic diagram (Fig. 1) does not match with the experimental (2.2). Revise it.

4. The authors claimed that TP acts as a reducing agent; however, no evidences are provided to support this statement.

5. The synthesis procedure follows hydrothermal treatment at 90 °C for 8 h. It has been already reported that the graphene oxide (GO) can be reduced to reduced graphene oxide (RGO) by hydrothermal treatment. (Journal of Alloys and Compounds 671(2016) 51-59, ACS Nano 4(2010 380-386). Hence, in this case, the hydrothermal process is responsible for reduction rather than TP. The authors need to prepare sample using TP and graphene without hydrothermal process and compare the results (XRD, FTIR, etc) to insure that the reduction is due to TP.

6. Page no 101, mention the time and temperature used in the freeze drying process.

7. The XRD explanation also does not match with the figure. The fig. 2a is meaningless. XRD figure from 2 θ values of 5 to 50° should be shown. For XRD, the authors can go through the following paper and cite it. (Ceramics International 41 (2015) 5656-5662).

8. XRD spectra of different formulations (examples; the graphite powder before exfoliation, graphite powder after exfoliation, after treating with TP, and after hydrothermal treatment) should be compared. For example;

9. Change the caption of fig. 3

10. There are several writing/grammar issues throughout the manuscript. Fix them.

Author Response

Dear reviewer,

 Thanks to your help to point out my errors of article.

 firstly, I'm really sorry that i made a big mistake in description of experiment and i have corrected it by describing afresh. Please see the attachment.

1. "Avoid abbreviations in the title" has been corrected.

2. Page 93, what did the authors use: graphene powder or graphite powder? it is graphene powder 

3. The schematic diagram (Fig. 1) does not match with the experimental (2.2). Revise it. 

4. The authors claimed that TP acts as a reducing agent; however, no evidences are provided to support this statement. 

5. The synthesis procedure follows hydrothermal treatment at 90 °C for 8 h. It has been already reported that the graphene oxide (GO) can be reduced to reduced graphene oxide (RGO) by hydrothermal treatment. (Journal of Alloys and Compounds 671(2016) 51-59, ACS Nano 4(2010 380-386). Hence, in this case, the hydrothermal process is responsible for reduction rather than TP. The authors need to prepare sample using TP and graphene without hydrothermal process and compare the results (XRD, FTIR, etc) to insure that the reduction is due to TP.

i realized that i made a mistake in this section and i corrected a new synthetic schematic also revised the description of synthesis. To be honest, in my work, hydrothermal treatment was adopted to obtain RGO from Go and then, RGO mixed with TP to modify the dispersive ability by using the noncovalent interaction to achieve long-term stability and dispersibility.

6. Page no 101, mention the time and temperature used in the freeze drying process. The final products were obtained by freeze-drying( -50°C, 72h) 

7. The XRD explanation also does not match with the figure. The fig. 2a is meaningless. XRD figure from 2 θ values of 5 to 50° should be shown. For XRD, the authors can go through the following paper and cite it. (Ceramics International 41 (2015) 5656-5662). 

8. XRD spectra of different formulations (examples; the graphite powder before exfoliation, graphite powder after exfoliation, after treating with TP, and after hydrothermal treatment) should be compared. For example;

questions 7 and 8, i changed the range of XRD from 5 to 40° and provided the XRD data of GO, rGO and TP/GE. 

9. "Change the caption of fig. 3" has been corrected

10. There are several writing/grammar issues throughout the manuscript. Fix them.

thanks! i really appreciate it  and i hope i can publish an article in coatings! Have a nice day

Round 2

Reviewer 1 Report

Though the Authors have tried to answer my questions, the quality of presentation is below standards. In my opinion, this work should be checked by professional, i.e. MDPI, language editing service.

Author Response

Dear reviewer,

 The whole article has been revised by English-editing service.

Reviewer 2 Report

The manuscript is improved as compared to the previous form; however, it still needs revision. Some of my previous comments are not answered and there are several mistakes in the manuscript. It needs a major revision. Please revise it carefully.

1. In the previous round of review (comment no 3), I asked the authors to show the schematic diagram as accordance with the experimental procedure given in section 2.2. In response to my comment, the authors changed the whole experimental and figure. This is not acceptable. I suggest the authors to write the previous experimental part in the manuscript and revise only figure 1 (schematic diagram) to make it clearer to the readers. Be sure, the schematic diagram should show all the steps.

2. In the previous round, the authors were asked to provide evidences to support their claim that the TP acts as a reducing agent (comment no 4) and clearly mention the role of hydrothermal process (comment no 5) in the reduction process. The authors did not answer the question clearly. Please, revise it again with the following points.

- You can cite some more references to support your claim that the TP acts as a reducing agent.

- It has been already proven that the hydrothermal treatment reduces the GO to rGO. (Journal of Alloys and Compounds 671(2016) 51-59, Ceramics International 42(2016)15247-15252, ACS Nano 4(2010 380-38). So, in this experiment, the reduction is due to the combined effect of hydrothermal treatment and TP. Mention this in the result and discussion section and cite the given references.

3. There are several writing/grammar issues throughout the manuscript.

Author Response

Dear reviewer,

 The schematic diagram has been revised and i cited some relative articles to support my issues. Thanks for your help, and the whole article has been edited by English-editing service of MDPI 

Round 3

Reviewer 2 Report

Now the paper can be accepted.