The Effects of Anodization Conditions on TiO₂ Nanotubes Features Obtained Using Aqueous Electrolytes with Xanthan Gum

Round 1

Reviewer 1 Report

This manuscript explores the use of xanthan gum (XG) and sodium fluoride as an aqueous electrolyte to modify the formation of TiO₂. The authors conducted experiments to control the morphology and arrangement of TiO₂ nanotubes by adjusting various parameters. The addition of xanthan gum in the electrolyte, aided by sodium fluoride, is crucial in regulating the growth of TiO₂ nanotubes. However, some issues remain unresolved. This paper is recommended for publication in the journal Inventions after minor modifications. The following comments and suggestions are provided:

 

1. In the abstract, the authors used the abbreviation FFT without explaining it first. It is best to use the full name of all abbreviations when they are first mentioned to avoid confusion for readers unfamiliar with the abbreviation.

2. The authors claimed that this is the first time xanthan gum has been used for TiO₂ nanotubes. However, they should avoid using words such as "first time" or "as we know" as there may be other papers in different languages or papers that the authors haven't read before have used a similar strategy.

3. In Figure 1c, there are two peaks during the nucleation process. The authors should explain the reason for the second peak and clarify if it is related to the addition of XG.

4. The scale bars in the SEM images are too small and blurry. The authors should enlarge them and improve their clarity.

5. From Figure 2d and 2i, it appears that the nanotubes with XG have thinner walls. The authors should explain the reason for this.

6. The authors should adjust the brightness and contrast of all figures in Figure 6 to make distinguishing the nanotubes at different pH levels easier.

 

7. The authors should proofread their work for spelling errors and modify their language to make it more formal.

The English is good. However, there are still some minor typos and mistakes.

Author Response

 

Comments and Suggestions for Authors

1. In the abstract, the authors used the abbreviation FFT without explaining it first. It is best to use the full name of all abbreviations when they are first mentioned to avoid confusion for readers unfamiliar with the abbreviation.

R./ The text has been modified according to the reviewer’s comments.

2. The authors claimed that this is the first time xanthan gum has been used for TiO2 nanotubes However, they should avoid using words such as "first time" or "as we know" as there may be other papers in different languages or papers that the. authors haven't read before have used a similar strategy.

R./ The authors appreciate your suggestion; however, we consider that it is important to highlight the novelty of this electrolyte, including the fact that the Xhantan gum has not been used before for producing TiO₂ nanotubes according to our scientific review in databases as ScienceDirect, Google scholar and Web of Science. In any case, the authors agree with the reviewer that documents out of the open literature might contain information like the one reported here.

3. In Figure 1c, there are two peaks during the nucleation process. The authors should explain the reason for the second peak and clarify if it is related to the addition of XG.

R./Those peaks could be related to the use of aqueous electrolytes; in a previous work (R. Aguirre O. and F. Echeverría E., “Effects of fluoride source on the characteristics of titanium dioxide nanotubes,” Appl. Surf. Sci., vol. 445, pp. 308–319, 2018, doi: 10.1016/j.apsusc.2018.03.139.) those peaks were present even though, in that case, the electrolytes used HF and NH₄F as fluoride sources. Because, of this evidence the authors do not believe there is any relationship with the presence of XG in the electrolyte.

4. The scale bars in the SEM images are too small and blurry. The authors should enlarge them and improve their clarity.

R./ The figures have been modified according to the reviewer’s comments.

5. From Figure 2d and 2i, it appears that the nanotubes with XG have thinner walls. The authors should explain the reason for this.

R./Using the SEM images, we measured the wall thickness of the nanotubes produced without and with XG; the values were 22.84 ± 3.37 and 26.43 ± 4.37 nm, respectively; thus, there is not a significant difference in values of the wall thickness.

6. The authors should adjust the brightness and contrast of all figures in Figure 6 to make distinguishing the nanotubes at different pH levels easier.

R./ The figure has been modified according to the reviewer’s comments.

 

7. The authors should proofread their work for spelling errors and modify their language to make it more formal.

R./ The text has been modified according to the reviewer’s comments.

 

Reviewer 2 Report

This study presents the fabrication of TiO2 nanotubes by using anodization method depending on Xanthan Gum addition concentration, anodization time, fluoride concentration and pH. The authors explained the TiO2 nanotube formation with current density variation and only characterized with scanning electron microscopy (SEM). There were so many papers that were studied the effect of anodization parameters on the TiO2 nanotubes formations, but adding Xanthan Gum into the solution is interesting. Some major revisions and editing are suggested:

 

1. The anodization conditions is not clear. For example applied voltage, solution temperature, OPC or constant voltage applied, …
2. XPS, EDX, XRD, … etc characterizations is needed to especially see how Xanthan Gum addition effect TiO2 nanotubes crystallinity and electronic structure.
3. As I see the authors measured TiO2 nanotube length from the cross sectional view of the nanotubes. However, this value is not actual length of the nanotubes due the tilt angle dependence.
4. In conclusion section; The authors writes “Anodization parameters like fluoride concentration, anodizing time, pH, and XG concentration do not affect the internal diameter values …” I expected especially that pH, fluoride concentration and anodizing time should affect the diameter of the nanotubes. Please explain the reason and discuss.
5. The definition of tn2 in line102 should be revised. I think the changing S3(1) with S3(2) should be enough.
6. The graph axises of the average value as a function of radius is not clear in different figures. Please revise or if not necessary remove them.
7. As I see there are three references related to alumina in the reference list. I think these references are not critical and please remove them.

Author Response

Reviewer 2 Comments:

1. The anodization conditions is not clear. For example applied voltage, solution temperature, OPC or constant voltage applied, …

R./ The text has been modified according to the reviewer’s comments.

 

2.XPS, EDX, XRD, … etc characterizations is needed to especially see how Xanthan Gum addition effect TiO2 nanotubes crystallinity and electronic structure.

R./ The text has been modified according to the reviewer’s comments.

 

3. I see the authors measured TiO2 nanotube length from the cross sectional view of the nanotubes. However, this value is not actual length of the nanotubes due the tilt angle dependence.

R./ All length measurements were calculated according to the tilt angle of each SEM image.

 

4.In conclusion section; The authors writes “Anodization parameters like fluoride concentration, anodizing time, pH, and XG concentration do not affect the internal diameter values …” I expected especially that pH, fluoride concentration and anodizing time should affect the diameter of the nanotubes. Please explain the reason and discuss.

R./In line with the reviewer comment, according to the scientific literature, the internal diameter is modified principally by voltage; however, pH and fluoride concentration variation could produce non-circular nanotubes, and in that case, the diameter could be affected. However, from our results, using aqueous electrolytes with XG, the internal diameter is not affected neither by pH, fluoride concentration nor anodizing time.

 

5. The definition of tn2 in line102 should be revised. I think the changing S3(1) with S3(2) should be enough.

R./ The text has been modified according to the reviewer’s comments.

 

6. The graph axises of the average value as a function of radius is not clear in different figures. Please revise or if not necessary remove them.

R./ The figure has been modified according to the reviewer’s comments.

 

7. As I see there are three references related to alumina in the reference list. I think these references are not critical and please remove them.

R./ The authors appreciate your suggestion to eliminate those references; however, those references help the reader to find other papers where the quantitative Fast Fourier Transformation (FFT) analysis was made and compare those results with our experimental findings.

Reviewer 3 Report

This paper describes the use of anodising titanium surfaces to form nanotube structures using an aqueous electrolyte made of xanthan gum and sodium fluoride. The organisation of the nanotubes was measured using the regularity factor from FFT images. The addition of xanthan gum to the aqueous electrolyte improved the organisation of the nanotubes, without affecting their packing. Based on the results of this experimental work, organised and homogeneous nanotube structures can be produced using an inexpensive and non-toxic aqueous electrolyte.

The main comments on the paper are as follows:

1.       The introduction is too short. I recommend expanding it.

2.       Supplement your conclusions with quantitative data obtained from the research. Give your conclusions in bullet points.

According to the reviewer, the paper could also be improved with the following minor corrections:

1.       Correct the explanation of the symbols under Eq. (1), starting without a capital letter.

2.       Arrange sources chronologically when citing them in groups.

Author Response

1. The introduction is too short. I recommend expanding it.

R./ The authors appreciate your suggestion; we added a paragraph to the introduction.

 

2. Supplement your conclusions with quantitative data obtained from the research. Give your conclusions in bullet points.

R./ The text has been modified according to the reviewer’s comments.

According to the reviewer, the paper could also be improved with the following minor corrections:

 

1. Correct the explanation of the symbols under Eq. (1), starting without a capital letter.

R./ The text has been modified according to the reviewer’s comments.

2. Arrange sources chronologically when citing them in groups.

R./ The text has been modified according to the reviewer’s comments.

 

Round 2

Reviewer 2 Report

The authors' revisions are mostly successful and the paper could be accepted in present form