Progress in the Preparation of Metal Oxide Electrodes for the Electrochemical Treatment of Organic Wastewater: A Short Review

Round 1

Reviewer 1 Report

I read with interest the manuscript “Progress in Preparation of Metal Oxide Electrodes, Electrode Activity, Lifespan, and Their Application in Organic Wastewater Treatment: A Short Review”. The manuscript is of interest to the readership of the journal and it is a good starting point for scholars who want to approach the topic of electrodes preparation and applications in the considered field. However, in some point the discussion is way too general and I suggest that the following is addressed before publication:

- Language should be carefully reviewed by a native speaker.

- Abstract: the abstract should contain less general and more specific critical results of the review work.

- Tables 1 and 2 are way too general and don’t really add any value to the manuscript, I would suggest that these are improved or removed.

- Many paragraphs of the review in my opinion are more similar to a textbook than an actual literature review, they outline very general principles suffering from a general lack of critical citation of the results of the specific papers reported in the literature. In this sense, paragraphs 3.2 and 4.2 are the best ones. I suggest that the authors add more specifics to the other general paragraphs.

- Language should be carefully reviewed by a native speaker.

Author Response

Reviewer #1:

I read with interest the manuscript “Progress in Preparation of Metal Oxide Electrodes, Electrode Activity, Lifespan, and Their Application in Organic Wastewater Treatment: A Short Review”. The manuscript is of interest to the readership of the journal and it is a good starting point for scholars who want to approach the topic of electrodes preparation and applications in the considered field. However, in some point the discussion is way too general and I suggest that the following is addressed before publication:

- Language should be carefully reviewed by a native speaker.

Our response: Thank you very much for your pertinent and scientific comments! We have meticulously reviewed the entire manuscript for grammatical accuracy. We appreciate your attention to detail and your commitment to maintaining high standards of scholarly communication.

- Abstract: the abstract should contain less general and more specific critical results of the review work.

Our response: We appreciate the time and effort you, along with the other reviewers, have dedicated to assessing our manuscript. Your comments and suggestions have been carefully considered in order to improve the quality and clarity of our work. In particular, we have revised and refined the abstract section, incorporating your valuable feedback. We sought to enhance the overall presentation and succinctness of this section, ensuring it provides a more precise and comprehensive overview of our paper.

- Tables 1 and 2 are way too general and don’t really add any value to the manuscript, I would suggest that these are improved or removed.

Our response: Thank you very much for your pertinent and scientific comments! In response to your suggestion, we have moved Tables 1 and 2 to the supplementary file to ensure the main body of the text remains concise and focused. We have retained only the essential information and relevant literature references in the main text. We believe this modification enhances the readability of the manuscript and allows readers to delve deeper into the specifics at their discretion.

- Many paragraphs of the review in my opinion are more similar to a textbook than an actual literature review, they outline very general principles suffering from a general lack of critical citation of the results of the specific papers reported in the literature. In this sense, paragraphs 3.2 and 4.2 are the best ones. I suggest that the authors add more specifics to the other general paragraphs.

Our response: Thank you for your observation regarding the structure of our review! Indeed, a significant portion of the initial sections is devoted to outlining the general principles that underpin our topic of discussion. This approach was deliberately chosen by us to ensure a comprehensive coverage of the topic, while maintaining a coherent logical flow throughout the review. By starting with a broad foundation, we are able to progressively delve into the nuances and specifics of the subject matter. We believe this strategy not only enhances the readability and understanding for those who are well-versed in the field, but also makes our review accessible to a wider audience, including potential readers who might be new to this area of study.

Comments on the Quality of English Language

- Language should be carefully reviewed by a native speaker.

Our response: Thank you very much for your pertinent and scientific comments! We have meticulously reviewed the entire manuscript for grammatical accuracy. We appreciate your attention to detail and your commitment to maintaining high standards of scholarly communication.

Reviewer 2 Report

1. Author can think of using the references in the past 5 years so that the collected data can be more comprehensive. 

2. Author should provide a more comprehensive review on writing each subsection. For example, line 46 to 66, the physical treatment technology can be improved. More references can be added. The current version seems very brief. Also, authors can add the list of past study in a table form for treatment technology. 

3. Line 171 to 208. The way the authors divide the section can be improved. This section can be further elaborate by adding the study using this method in a table form. 

4. Figure 3, any citation for this work?

5. Table 3 can be improved if the authors add more relevant studies that utilize this electrode types and indicates is performance. 

6. Table 4 same comments as comment 5. 

7. I think author need to include the performance of these metal oxide electrodes performance in a table form for better clarification. 

8. What is the novelty of this manuscript? Please highlight in introduction or conclusion. 

Author Response

Reviewer #2:

1. Author can think of using the references in the past 5 years so that the collected data can be more comprehensive.

Our response: Thank you for your attention to the details of our manuscript! A majority of the cited references are published within the last five years. This approach ensures that our research discussion is grounded in the most recent scientific developments and contributes to the ongoing discourse with updated insights.

2. Author should provide a more comprehensive review on writing each subsection. For example, line 46 to 66, the physical treatment technology can be improved. More references can be added. The current version seems very brief. Also, authors can add the list of past study in a table form for treatment technology.

Our response: Thank you very much for your pertinent and scientific comments! We have carried out the necessary modifications and augmentations to the relevant section of our manuscript.

3. Line 171 to 208. The way the authors divide the section can be improved. This section can be further elaborate by adding the study using this method in a table form.

Our response: Thank you very much for your pertinent and scientific comments! We sincerely appreciate your detailed feedback and those from the other reviewers. Taking into account the collective comments, we have conducted significant revisions on the mentioned section of the manuscript and the associated Figure 1. These revisions are intended to provide a clearer and more effective presentation of the content, ensuring our arguments and findings are accurately and concisely conveyed. We believe these changes greatly enhance the clarity of our manuscript, making it more accessible and impactful for readers.

4. Figure 3, any citation for this work?

Our response: Thank you very much for your pertinent and scientific comments! All the images in Figure 3 of the manuscript were created by the authors of this work and do not directly replicate any content from other published works. Figure 3 is employed to provide a more intuitive display of the main fabrication methods for metal oxide electrodes, such as the thermal decomposition method, chemical deposition method, electrochemical deposition method, and others, as mentioned on Page 4, Line 184.

5. Table 3 can be improved if the authors add more relevant studies that utilize this electrode types and indicates is performance.

Our response: Thank you very much for your pertinent and scientific comments! Additional relevant studies were added in Table 3(what was previously Table 3 is now Table 1) to offer readers a more comprehensive understanding of the context.

6. Table 4 same comments as comment 5.

Our response: Thank you very much for your pertinent and scientific comments! We made some modifications to Table 4 (what was previously Table 4 is now Table 2).

7. I think author need to include the performance of these metal oxide electrodes performance in a table form for better clarification.

Our response: Thank you for your insightful comments! We agree with your observation and would like to highlight that in the diverse studies we referenced, researchers have indeed utilized varying substrates, different models of electrodes, distinct power supply modes, and variable electrochemical treatment durations. These variables introduce a level of uncertainty in the lateral comparisons across these studies. However, the main focus of our review lies in the utilization and structural innovation of metal oxide electrode materials, as well as the specific problems they address in their respective studies.

8. What is the novelty of this manuscript? Please highlight in introduction or conclusion.

Our response: Thank you for your insightful comments! In response, we have diligently revised our abstract and conclusion sections to ensure they deliver a clear and succinct summary of our study. Compared to other recent reviews, our work provides a broader narrative scope, spanning from the research background, to electrochemical treatments, and onto the advantages of metal oxide electrodes. This comprehensive overview allows readers to fully understand the progress and significance of this field. Moreover, we have innovatively categorized metal oxide electrodes into single metal oxide electrodes and metal oxide composite electrodes. This classification provides a new perspective to discuss and compare their respective features, thereby enhancing the depth and novelty of our review. We greatly appreciate your role in assisting us to refine our manuscript, ensuring its clarity and depth are aligned with the standards of our scientific community.

Reviewer 3 Report

The paper review recent achievements in the progress in preparation of metal oxide electrodes and and their application in organic wastewater treatment by electrochemical advanced oxidation processes. Initially, classification and characteristic of various physical and chemical methods of wastewater treatment is detailed. Then, the fundamental aspects and recent advances of metal oxide electrodes preparations  and its applications in the elimination of organics is reviewed. Furthermore, some aspects of single metal oxide electrodes and metal oxide composite electrodes advantages and progress in electrochemical wastewater treatment are discussed. The review is interesting and worthy of publication. However, some critical aspects should be considered:

- The title of the article would more convincing if it was as follows "Progress in preparation of metal oxide electrodes for the organic wastewater treatment: a short review". At the same time, such a review already exists

(https://doi.org/10.1007/s11356-013-2313-6), I would like the authors to justify their difference. In addition, there are a lot of reviews published recently and devoted to electrochemical methods for removing various pollutants.

https://doi.org/10.1039/D2QM01294D

https://doi.org/10.1016/j.psep.2017.09.014

https://doi.org/10.1007/s10311-023-01610-5

https://doi.org/10.1016/j.scitotenv.2022.159092

https://doi.org/10.1007/s13762-021-03762-9

All this should be discussed in the introduction.

- A discussion of the relative advantages of electrochemical processes with use the metall oxide electrodes compared with other treatment system (in particular AOPs) is missing. 

- I strongly encourage the authors split introduction and to introduce a section about advantages of electrochemical advanced oxidation processes, which is a growing electrochemical remediation process.

- Figures must be able to ‘stand alone’. This means that readers should be able to understand the key messages by reading figures along with their captions, without the need to refer to main texts in the manuscript. Therefore, all figure captions should include one to three sentences to distill the "take-home" messages, e.g., key findings and/or conclusions. Unfortunately, the captions under the figures are very poor.

- Most figures in this manuscript contain texts that are too small to read. Authors need to increase the sizes of their embedded texts and make sure they are readable particularly in Figures 3–5.

- All text should be written without numbering  in the text. Orphan sentences should be avoided. There are quite a few of these in the manuscript. Authors need to check through the entire manuscript.

I think, authors must obtain written permission from publishers to reprint figures and write permission at the end of figure captions, as per the publication ethics guidelines.

Many redaction mistakes are observed. Therefore, English should be thoroughly revised in the whole document.

Author Response

Reviewer #3:

The paper review recent achievements in the progress in preparation of metal oxide electrodes and and their application in organic wastewater treatment by electrochemical advanced oxidation processes. Initially, classification and characteristic of various physical and chemical methods of wastewater treatment is detailed.  Then, the fundamental aspects and recent advances of metal oxide electrodes preparations and its applications in the elimination of organics is reviewed.  Furthermore, some aspects of single metal oxide electrodes and metal oxide composite electrodes advantages and progress in electrochemical wastewater treatment are discussed. The review is interesting and worthy of publication. However, some critical aspects should be considered:

- The title of the article would more convincing if it was as follows "Progress in preparation of metal oxide electrodes for the organic wastewater treatment: a short review".

Our response: Thank you for your valuable suggestions! We have carefully considered the feedback from you and another reviewer, and have decided to adjust our title to better reflect the essence of our work. The final title we've settled on is: "Progress in the Preparation of Metal Oxide Electrodes for Electrochemical Treatment of Organic Wastewater: A Short Review". We believe this title more accurately represents the content and scope of our study, and we appreciate your guidance in this revision process.

At the same time, such a review already exists (https://doi.org/10.1007/s11356-013-2313-6), I would like the authors to justify their difference.  In addition, there are a lot of reviews published recently and devoted to electrochemical methods for removing various pollutants.

https://doi.org/10.1039/D2QM01294D

https://doi.org/10.1016/j.psep.2017.09.014

https://doi.org/10.1007/s10311-023-01610-5

https://doi.org/10.1016/j.scitotenv.2022.159092

https://doi.org/10.1007/s13762-021-03762-9

All this should be discussed in the introduction.

Our response: Thank you very much for your pertinent and scientific comments! While we acknowledge the significant contributions of the referenced work "https://doi.org/10.1007/s11356-013-2313-6", our research presents an expanded scope and builds upon more recent studies from the past three years.

In addition to that, our work summarizes the types and hazards of organic wastewater, highlights the significant advantages of metal oxide electrodes in electrocatalytic oxidation treatment for organic wastewater, and introduces the primary preparation methods of metal oxide electrodes. Furthermore, we provide a more definitive classification of metal oxide electrodes, expanding the knowledge base in this field.

The work in "https://doi.org/10.1007/s11356-013-2313-6" predominantly emphasizes the application of SnO₂, PbO₂, IrO₂, and RuO₂ metal oxide anodes and their effectiveness in the wastewater treatment process. While it provides valuable insights, we believe our study offers a broader perspective and includes newer developments in the field.

Thank you for pointing out the other references. It's worth noting that these documents each review different aspects, including wastewater treatment, removal of azo dyes, comparisons between various advanced oxidation technologies, etc. Each one of these works focuses on a specific subset within the broader scope of the field. Our review, however, is differentiated by its focus and contribution. While acknowledging the importance of these previously reviewed subjects, our work attempts to address a unique set of issues and aspects not covered by these papers. Thus, we believe our manuscript does not overlap with the content covered in the cited literature. Once again, we appreciate your meticulous attention to detail and your helpful comments, which certainly contribute to the improvement of our work.

- A discussion of the relative advantages of electrochemical processes with use the metall oxide electrodes compared with other treatment system (in particular AOPs) is missing.

Our response: Thank you very much for your pertinent and scientific comments! The related content (advantages of electrocatalytic oxidation over other AOPs) was added to Page 2, Line 66. The main advantages of metal oxide electrodes were shown in Figure 2.

- I strongly encourage the authors split introduction and to introduce a section about advantages of electrochemical advanced oxidation processes, which is a growing electrochemical remediation process.

Our response: Thank you very much for your pertinent and scientific comments! The relevant advantages of electrochemical oxidation technology have been complemented (From Line 60).

- Figures must be able to ‘stand alone’. This means that readers should be able to understand the key messages by reading figures along with their captions, without the need to refer to main texts in the manuscript.  Therefore, all figure captions should include one to three sentences to distill the "take-home" messages, e.g., key findings and/or conclusions.  Unfortunately, the captions under the figures are very poor.

Our response: Thank you very much for your pertinent and scientific comments! Both Figure 3 and Figure 4 have been thoroughly revised. They now clearly depict the contents of the referenced literature via flowcharts and diagrams, complemented by additional key textual annotations.

- Most figures in this manuscript contain texts that are too small to read.  Authors need to increase the sizes of their embedded texts and make sure they are readable particularly in Figures 3–5.

Our response: Thank you very much for your pertinent and scientific comments! The image size of Figure 3 has been resized, and Figures 4 - 5 have been redrawn.

- All text should be written without numbering in the text. Orphan sentences should be avoided.  There are quite a few of these in the manuscript. Authors need to check through the entire manuscript.

Our response: Thank you very much for your pertinent and scientific comments! All the numbers in the text have been deleted, the corresponding statements have also been adjusted.

I think, authors must obtain written permission from publishers to reprint figures and write permission at the end of figure captions, as per the publication ethics guidelines.

Our response: Thank you very much for your pertinent and scientific comments! Figure 3 and Figure 4 have been redrawn for clearer representation and text display. Consequently, this manuscript no longer includes any images from other published works, thus eliminating any copyright concerns.

Reviewer 4 Report

Dear authors,

I studied your report about using metal oxides in electrochemical wastewater treatment. It is interesting and valuable. However, there are some minor issues that need to be addressed before publication.

11-      Your report is about electrochemical wastewater treatment method; therefore, it is better that the electrochemical is mention in title.

22-      In abstract section, what does ‘’the metal oxide electrolyte’’ refer to?

33-      In the tables, it is better to add a separate column for references.

44-      In the introduction section, it is better that ‘’advanced oxidation technology’’ is referred to as a chemical treatment technology subset.

55-      Please add an explanation about electrochemical oxidation mechanism. In addition, please add an explanation about reactions in Figure 1.

66-      In the Figure 3, please specify (a), (b),… shows what method.

77-      In page 10, line 330, should ‘’metal oxide’’ change ‘’metal oxide composite’’?

88-      In the summery section, pleas add a comparison about two types of metal oxides (metal oxide composition and single metal oxide).

99-It is better get permission for figures.

I

 Moderate editing of English language required

Author Response

Reviewer #4:

Dear authors,

I studied your report about using metal oxides in electrochemical wastewater treatment. It is interesting and valuable. However, there are some minor issues that need to be addressed before publication.

11 - Your report is about electrochemical wastewater treatment method; therefore, it is better that the electrochemical is mention in title.

Our response: Thank you for your valuable suggestions! We have carefully considered the feedback from you and another reviewer, and have decided to adjust our title to better reflect the essence of our work. The final title we've settled on is: "Progress in the Preparation of Metal Oxide Electrodes for Electrochemical Treatment of Organic Wastewater: A Short Review". We believe this title more accurately represents the content and scope of our study, and we appreciate your guidance in this revision process.

22 - In abstract section, what does ‘’the metal oxide electrolyte’’ refer to?

Our response: Thank you very much for your pertinent and scientific comments! The phrase “the metal oxide electrolyte” should have been revised to "the metal oxides". Furthermore, we have rewritten the entire abstract, refining the expression for enhanced conciseness.

33- In the tables, it is better to add a separate column for references.

Our response: Thank you very much for your pertinent and scientific comments! A separate column for references has been added to each table.

44 - In the introduction section, it is better that ‘’advanced oxidation technology’’ is referred to as a chemical treatment technology subset.

Our response: Thank you for your insightful suggestion! We appreciate your attention to the nuances within our study, and we have added information to clarify that advanced oxidation technology is a subset of chemical treatment technologies.

55 - Please add an explanation about electrochemical oxidation mechanism. In addition, please add an explanation about reactions in Figure 1.

Our response: Thank you very much for your pertinent and scientific comments! In line with your feedback, we have now added Equation (1) directly beneath Figure 1. This addition aims to more clearly elucidate the electrocatalytic oxidation process of organic pollutants. We believe that this modification will provide readers with a more direct and comprehensive understanding of the process in question.

66 - In the Figure 3, please specify (a), (b),… shows what method.

Our response: Thank you very much for your pertinent and scientific comments! We have followed your advice and added the corresponding textual annotations to the top right corner of Figure 3(a), Figure 3(b), and subsequent parts as appropriate. We believe these additions will enhance the clarity and comprehensibility of our figures.

77 - In page 10, line 330, should ‘’metal oxide’’ change ‘’metal oxide composite’’?

Our response: Thank you very much for your pertinent and scientific comments! We appreciate your keen observation and agree that using the term "metal oxide composite" indeed provides greater clarity and specificity in identifying the subject of our discussion compared to the term "metal oxide".

88 - In the summery section, pleas add a comparison about two types of metal oxides (metal oxide composition and single metal oxide).

Our response: Thank you very much for your pertinent and scientific comments! A comparison about two types of metal oxides was added in the summery section.

99 - It is better get permission for figures.

Our response: Thank you very much for your pertinent and scientific comments! Figure 3 and Figure 4 have been redrawn for clearer representation and text display. Consequently, this manuscript no longer includes any images from other published works, thus eliminating any copyright concerns.

Round 2

Reviewer 1 Report

The manuscript was revised according to most of the suggestions. It is suitable for publication

Manuscript language has been improved. Only minor editing is required

Author Response

Our response: We greatly appreciate your time and effort in reviewing our manuscript! We have conducted another thorough check to ensure that any remaining expressions are appropriately revised. Once again, we express our sincere gratitude for your diligent review and guidance.

Reviewer 3 Report

The authors carefully revised their original version of the manuscript. But, before publication, it still requires some more minor changes. For example, the caption under Fig. 3. requires modification. You need to enable decryption (a-d). There are still orphan sentences (line 81-82 p. 3 "There are mainly two ways for the oxidation of organic pollutants: Direct electrocatalytic oxidation:") with a double colon. And there are many such proposals. The grammar needs to be corrected. The references also needs to be corrected. See journal requirements. Also, I think that the supplementary material for the review article is redundant. Tables in the supplementary materials should be integrated into the text of the manuscript.

Author Response

Our response: I would like to express my sincere gratitude for your insightful and constructive comments, which have greatly contributed to the enhancement of our manuscript.

1）We have revised the caption under Figure 3 and included notations "a - f" in sequence for the various preparation methods mentioned in the figure. This improvement has also been reflected in the main text (highlighted sections from Line 200 to Line 223). We believe this will make the figure more accessible and understandable to the readers.

2）The grammatical errors you pointed out have been carefully corrected (Line 95 - Line 103; Line 359 - Line 365; Line 443 - Line 450). We appreciate your attention to detail in helping us improve the readability and clarity of our manuscript.

3）In line with your suggestion, and that of another reviewer, we have made the following adjustment: The main content from the previous version's Table S1 and Table S2 has been meticulously extracted and placed in the corresponding positions within the main text (The supplementary file has been removed). This can be seen in the highlighted sections from Line 30 to Line 34 and from Line 37 to Line 65. We believe this revision greatly enhances the flow and coherence of our manuscript.

Once again, thank you for your time and valuable feedback. We believe that with your guidance, the revised manuscript has been significantly improved and hope it now meets the high standards of the journal.