Phenomenal Insight into Electrochemically Induced Photocatalytic Degradation of Nitrobenzene on Variant Au-Modified TiO₂ Nanotubes

Response to Reviewer 1 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Must be improved

Revised based on comments

Are all the cited references relevant to the research?

Must be improved

Revised based on comments

Is the research design appropriate?

Can be improved

Revised based on comments

Are the methods adequately described?

Yes

Thank you.

Are the results clearly presented?

Can be improved

Revised based on comments

Are the conclusions supported by the results?

Can be improved

Revised based on comments

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: The introduction must be completely rewritten, improving the English writing and making the sentences coherent as well as updating the references.

Response 1: Thank you for pointing this out. We are very sorry for our incorrect writing. As the Reviewer's good instruction, we have tried our best to rewrite and revise the English of the whole manuscript carefully. We hope the language is now acceptable for the next review process.

As the Reviewer's suggestion, we added more recent references in the discussion and hope that the citation of this paper will enable the readers easier to follow. The latest literature is marked in red in the revised manuscript (References 1, 7, 8, 12, 22, 28, 33 and 35). From your comments, we can see that you have made a lot of achievements in this field.

Special thanks to you for your good comments.

Comments 2: In the experimental part in the Characterization of Catalyst section, it should be improved because it is not sufficiently clear and illustrate the preparation through chemical reactions.

Response 2: As the Reviewer's suggestion, we added more key experimental details in the paper and explain them in line 334-338, line 344-345, line 351-354,and line 360-367. We are very sorry for our carelessness, and also feel great thanks for your point out them.

Comments 3: In the results, in Fig 1 the microphotographs should be better analyzed, hopefully using specialized software.

Response 3: As the Reviewer's suggestion, we added more analysis about the SEM picture. In addition, we have also modified some images to make readers to observe the morphology of TiO₂ nanotubes and the loading of Au nanoparticles inside the tubes more clearly. The revised content in the manuscript is in line 120 to 124, and line 126 to 130.

Comments 4: The analysis in Figure 4. Cyclic Voltammetry curve of NB in the dark is regular; therefore the authors should be clearer here.

Response 4: As the Reviewer's suggestion, we clearly state that the Cyclic Voltammetry curve of NB in the dark is regular. The added content in the manuscript is in line 188 to 189.

Comments 5: The results presented by the authors in Fig. 6 The degradation of NB with the prepared samples should be expanded

Response 5: As the Reviewer's suggestion, we expanded the results about the Fig. 6. The revised content in the manuscript is in line 219 to 226, and line 248 to254.

Response to Reviewer 2 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Can be improved

Revised based on comments

Are all the cited references relevant to the research?

Must be improved

Revised based on comments

Is the research design appropriate?

Must be improved

Revised based on comments

Are the methods adequately described?

Can be improved

Revised based on comments

Are the results clearly presented?

Can be improved

Revised based on comments

Are the conclusions supported by the results?

Yes

Thank you

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: The novelty of the work needs to be clearly stated in the introduction, what is different in the manuscript as compared to what has been previously reported.

Response 1: As the Reviewer's suggestion, we cleared the novelty of our manuscript and rewrote part of the content in the introduction to stress the novelty of the manuscript.  The revised content in the manuscript is in line 97 to 108, line374 to 378, and line 383 to386.

Comments 2: Considering that the system being used is visible light active nanosystem. A sound advantage relatively to standard oxide based nanosystems. The authors are encouraged to highlight such a superior advantage & efficiency. Th authors are encouraged to mention this paramount aspect at least at the end section of the manuscript just before the conclusion section.

Response 2: As the Reviewer's suggestion, we highlighted the superior advantage & efficiency of the material under visible light active. The added content in the manuscript is in line 300 to 305.

Comments 3: Figure 6C and Figure 7 have no error bars. It is outmost important that they are included, and the statistical analysis is added and discussed.

Response 3: All experimental data in the paper are the mean data of three parallel experiments, and the difference between the three data is within the range of plus or minus 5%. Due to the small absolute value of the data in the graph, the difference is also small. The error scale plotted in the actual graph is not clearly displayed. Therefore, error analysis is not added to the experimental data in the paper, but we have added an explanation of the experimental error to the paper. The added content in the manuscript is in line 336 to 338.

Comments 4: The results that are mentioned in the manuscript needs to be critically compared with similar results so that a concrete conclusion can be supported.

Response 4: As the Reviewer's suggestion, we add a description and analysis/discussion of the results with a comparison with similar studies. The contrasting expounds in the manuscript is in line 97 to 108, line248 to 255, and line 301 to 305. 

Response to Reviewer 3 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Must be improved

Revised based on comments

Are all the cited references relevant to the research?

Can be improved

Revised based on comments

Is the research design appropriate?

Must be improved

Revised based on comments

Are the methods adequately described?

Must be improved

Revised based on comments

Are the results clearly presented?

Must be improved

Revised based on comments

Are the conclusions supported by the results?

Must be improved

Revised based on comments

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: For the title of this paper, it is recommended to avoid abbreviations of NB and NTs are and replace them with full names of “nitrobenzene” and “nanotubes” to enhance clarity.

Response 1: As the Reviewer's suggestion, we replaced abbreviations with full names, and the modified parts have been colored red in the article.

Comments 2: On Page 3 line 128-130, it is important to provide information about the duration of treatment at 1.2 V during the Au incorporation process. Additionally, clarify whether the experimental duration can influence the incorporation content of Au particles and particle size. Address English language issues in this section as well. For example, in line 131, revise "...using an electrochemical reduction at…" to "...using an electrochemical reduction method/strategy at…". Furthermore, in line 132, modify "1.2 V on the different concentrations" to "1.2 V under solutions with different concentrations."

Response 2: As the Reviewer's suggestion, information about the duration of treatment at 1.2 V during the Au incorporation process was added in the manuscript in line 335 to line 337. The experimental duration will influence the incorporation content of Au particles and particle size, so the parameters such as time, voltage, and temperature will be controlled uniformly during the whole experiment, making it convenient for the prepared samples to have comparability with each other.

Besides, we revised the English language issues in the article.The revised content in the manuscript is in line 334 to line 335. Thank you for pointing this out. We are very sorry for our incorrect writing. As the Reviewer's good instruction, we have tried our best to rewrite and revise the English of the whole manuscript carefully. We hope the language is now acceptable for the next review process.

Comments 3:  On page 4 line 152-153, figure captions for Figure 1 (g) and (h) are missing.

Response 3: Thank you for pointing this out.We are very sorry for our incorrect writing. As the Reviewer's good instruction, we have added the figure captions for Figure 1 (g) and (h).

Comments 4: The authors are suggested to provide additional experimental evidence regarding the size and distribution of Au nanoparticle. Apart from the EDS spectra in Figure 2, consider providing SEM/EDS mapping to illustrate the distribution of Au nanoparticles on the surface of TiO₂ nanotube. Furthermore, consider including SEM images at higher magnifications or TEM images to reveal how Au particles are incorporated on the surface of TiO₂ nanotubes, their morphology, and their bonding with TiO₂.

Response 4: As the Reviewer's suggestion, we added more analysis about the experimental evidence regarding the size and distribution of Au nanoparticle. In addition, we have also modified some SEM images to make readers to observe the morphology of TiO₂ nanotubes and the loading of Au nanoparticles inside the tubes more clearly. The revised content in the manuscript is in line 120 to 124, and line 126 to 130. Due to limited modification time and experimental funding, we are currently unable to provide TEM images. However, we have made every effort to provide evidence of the surface modification of the catalyst by metal particles, which has a positive effect on degradation efficiency. As shown in Figure 1f, the Au particles are successfully incorporated on the surface and interior of TiO₂ nanotubes, and the results of degradation experiments also show that such modification can enhance its catalytic effect in both PC and PEC conditions.

Comments 5: For Figure 1, it is recommended to maintain a consistent scale bar size in all the images from (a) to (h) to enhance visual clarity.

Response 5: As the Reviewer's suggestion, we revised the scale of SEM images in Figure 1 and

maintain a consistent scale bar size in all the images from (a) to (h) to enhance visual clarity. 

Special thanks to you for your good comments.

Comments 6: For the XRD pattern in Figure 3, it is suggested to mark the Au peak more clearly and differentiate it from the TiO2 anatase peak. Additionally, clarify if there are any differences in the Au XRD peak between Figure 3(b) and 3(c). Discuss whether different concentrations of Au-containing solutions influence the final formation of Au nanoparticles.

Response 6: As the Reviewer's suggestion, we revised the XRD pattern in Figure 3. In the case of Au/TiO₂ nanotubes, they correspond to the mixture phase and exhibit no significant difference from pristine TiO₂ nanotubes. The peak at 2 theta values of 38.21°, 44.32° and 63.80° matches the (111), (200)and (220)planes of the Au phase in the patterns(JCPDS 65-2870), confirming the presence of metallic Au. Subsequent analyses, in combination with SEM and EDS, can demonstrate the successful preparation of Au/TiO₂ nanotubes.

Comments 7: It would be valuable to determine the actual incorporation content of Au on TiO2. Consider conducting ICP-MS experiments to experimentally determine the real content of Au in TiO2. This could help explain the differences in catalytic properties and shed light on why 0.6 g/L and 0.4 g/L are the optimal concentrations for degradation for photocatalysis (PC) and photoelectrocatalysis (PEC).

Response 7: As the Reviewer's suggestion, ICP experiments were used to experimentally determine the real content of Au in TiO₂ as shown in Table 1. The ICP test results, in conjunction with other analytical tests, explain the differences in catalytic performance and the optimal concentrations for photocatalytic (PC) and photocatalytic (PEC) degradation.

Special thanks to you for your good comments.

4.Comments on the Quality of English Language

Comments 1: For the English of this paper, the authors are suggested to pay closer attention to the coherence and logic between sentences throughout the paper. For instance, on page 1 line 31-36, the author discussed that “Scholars have extensively investigated methods to mitigate these drawbacks…can enhance visible light absorption.” The coherence between the second and third sentences is missing, making it challenging for readers to follow the article effectively. Enhance coherence by revising this section as follows: “To effectively reduce the bandgap and enhance visible light adsorption, various strategies have been employed during the synthesis process, including defect introduction, specific elements doping, and semiconductor incorporation,. For instance, incorporating g-C3N4 into TiO2 can form a heterojunction structure, including traditional Type II and Z scheme, which effectively alters the movement of charge carriers.”

Response 1: Thank you for pointing this out. We are very sorry for our incorrect writing. As the Reviewer's good instruction, we have tried our best to rewrite and revise the English of the whole manuscript carefully. We hope the language is now acceptable for the next review process.

Special thanks to you for your good comments.