Modification of α-Fe2O3 Nanoparticles with Carbon Layer for Robust Photo-Fenton Catalytic Degradation of Methyl Orange
Banasri Roy
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript presents the results of studies of the photocatalytic oxidation of methyl orange on α-Fe2O3 nanoparticles modified with a carbon layer. Unfortunately, I cannot recommend this manuscript for publication in its present form for the following serious reasons:
1. Currently, there are a lot of publications devoted to the study of the photoctalytic activity of α-Fe2O3 and its modified products. There are also many studies devoted to the hydrothermal synthesis of α-Fe2O3 with its subsequent use in photocatalysis. Authors need to seriously justify the novelty of their work
2. Unfortunately, I did not see any convincing evidence of the formation of a carbon layer on the surface of α-Fe2O3. The authors need to conduct further research using still other methods, such as XPS.
3. How was the concentration of methyl orange measured? How was the effect of pH studied? The absorption spectra of methyl orange will have different absorption lengths as the pH changes.
4. No discussion of kinetic data. It is need to discuss them in more detail
5. The mechanism of methyl orange oxidation needs to be substantiated. Research is needed using scavengers of various oxidizing agents.
6. When H2O2 is added, the oxidation of methyl orange occurs mainly through a photo-Fenton-like process. There is no information about this in the discussion.
7. Careful editing of the manuscript is required. The manuscript must be formatted in accordance with the requirements of the journal Catalysts. For example, the experimental part should appear after the results discussion section. Figure 1, I think it needs to be moved to the materials and methods section, the minus in formula 2 is missing, line 287, etc.
Author Response
Reviewer #1
Thank you for your detailed feedback and we assure you that we carefully addressed all the mentioned issues in our manuscript. Your suggestions will help improve the clarity and quality of our work, ensuring that it meets the standards of the Catalysts Journal.
1. Currently, there are a lot of publications devoted to the study of the photocatalytic activity of α-Fe2O3 and its modified products. There are also many studies devoted to the hydrothermal synthesis of α-Fe2O3 with its subsequent use in photocatalysis. Authors need to seriously justify the novelty of their work.”
Reply: Thank you for the constructive feedback. We understand the importance of clearly demonstrating the novelty of our work, especially in a field as extensively studied as the photocatalytic activity of α-Fe2O3 and its solvothermal synthesis. In compliance with this comment, the introduction on page 2 is modified to highlight our research's novelty and unique contributions. In addition, the reference list is updated with more relevant works.
- Unfortunately, I did not see any convincing evidence of the formation of a carbon layer on the surface of α-Fe2O3. The authors need to conduct further research using still other methods, such as XPS.”
Reply: Many thanks for the valuable comment. We understand the importance of providing evidence for the formation of a carbon layer on the surface of α- Fe2O3. However, access to XPS is very limited at the moment and in response to this comment, we rely on TEM and EDX mapping analysis to confirm the formation and content of the carbon layer. Detailed discussion has also been added and highlighted in the revised manuscript on pages 3 and 4.
3. How was the concentration of methyl orange measured? How was the effect of pH studied? The absorption spectra of methyl orange will have different absorption lengths as the pH changes.”
Reply: Thank you for your insightful comments. We appreciate the opportunity to clarify our methodologies and provide details regarding measuring methyl orange concentration and studying pH effects. In response to the reviewer's questions, the details of the impact of the pH study and methyl orange concentration measurement are added to the manuscript on pages 7, 9 and 13 respectively.
4 No discussion of kinetic data. It is need to discuss them in more detail.”
Reply: Many thanks for the suggestion. These detailed kinetic data and discussions are included in the revised manuscript on pages 8 and 9 to provide a comprehensive understanding of the photocatalytic process and to address the reviewer's comments thoroughly.
- The mechanism of methyl orange oxidation needs to be substantiated. Research is needed using scavengers of various oxidizing agents.”
Reply: Thank you for your constructive comment. We provided the experimental results of using various scavenger agents like isopropanol(IPA), ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) and p-benzoquinone (p-BQ). The detailed results and discussion are added on page 10 (section: 2.5.3. Trapping species analysis) and the mechanism discussion is revised accordingly on page 11 (2.5.5 Mechanism in Photocatalytic Degradation) in the revised manuscript.
6 When H2O2 is added, the oxidation of methyl orange occurs mainly through a photo-Fenton-like process. There is no information about this in the discussion.”
Reply: We agree with the reviewer, about the role of hydrogen peroxide (Hâ‚‚Oâ‚‚) in the presence of Fe(II)/Fe(III) redox of a photo-Fenton-like process in the oxidation of methyl orange. A detailed discussion in the revised manuscript has been elaborated on page 11 to clarify this point.
7 Careful editing of the manuscript is required. The manuscript must be formatted following the requirements of the journal Catalysts. For example, the experimental part should appear after the results discussion section. Figure 1, I think it needs to be moved to the materials and methods section, the minus in formula 2 is missing, line 287, etc.”
Reply: We appreciate the reviewer’s suggestions for improving the manuscript and ensuring it aligns with the requirements of the Catalysts journal. We will reformat the manuscript according to the requirements of the Catalysts journal. This includes placing the experimental section after the discussion of the results and ensuring proper formatting of all sections on pages 12 and 13. We also relocated Figure 1 to the materials and methods section, where it will provide visual support for the experimental setup and procedures described in that section.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis research aimed to synthesize carbon-modified Fe2O3 nanoparticles by solvothermal technique and study their methyl orange photodegradation activity. The catalysts were characterized by XRD, FTIR, SEM, TEM, and UV-VIS spectrophotometry techniques. The C modification reportedly enhances the photocatalytic activity of Fe2O3 and is attributed to the conductive carbon layer, reducing the electron-hole recombination rates. This is a good article in which the authors cover essential aspects, such as the recyclability of the catalysts, catalysts dose study, etc. No doubt, the idea of the work is good. A few queries need to be replied to before going to the next stage.
1. Synthesis of Fe2O3 nanoparticles modified with carbon layer: Authors used many chemicals (terephthalic acid (H2BDC), N- 71 dimethylformamide (DMF), dicyandiamide (DCDA), and ethanol anhydrous (C2H6O)) for the synthesis of Fe2O3 nanoparticles modified with carbon layer. What are the roles of each chemical here? Mention with respective chemical equations. How did they decide this method to use? Did they optimize the process?
2. The particle size and porosity are two important aspects of the photocatalysts. Authors should report gas adsorption experiments to quantify before and after applications.
3. Mechanism in Photocatalytic Degradation: Where is the Figure 11? The article seems incomplete.
Author Response
Reviewer# 2
- Synthesis of Fe2O3 nanoparticles modified with carbon layer: Authors used many chemicals (terephthalic acid (H2BDC), N- 71 dimethylformamide (DMF), dicyandiamide (DCDA), and ethanol anhydrous (C2H6O)) for the synthesis of Fe2O3 nanoparticles modified with carbon layer. What are the roles of each chemical here? Mention with respective chemical equations. How did they decide this method to use? Did they optimize the process?
Reply: Thank you for your insightful comments and questions. In reply to this comment, we added a detailed discussion of the materials' role in the synthesis of the Fe2O3@C nanoparticles in the experimental section on page 12 (3.2. Synthesis of Fe2O3 nanoparticles modified with carbon layer) in the revised manuscript.
2. The particle size and porosity are two important aspects of the photocatalysts. Authors should report gas adsorption experiments to quantify before and after applications.”
Reply: Thank you for your valuable comments. We agree that particle size and porosity are critical aspects of photocatalysts, and we appreciate the suggestion to include gas adsorption experiments. To address the reviewer's comment, we conducted gas adsorption experiments to quantify the surface area and porosity of the photocatalysts. The results demonstrated that the Fe2O3 nanoparticles modified have a high surface area, which is critical for their photocatalytic performance. As shown in section 2.3 on pages 5 and 6 we added detailed results and discussion of the catalyst’s surface area measurements as shown in Figure 5.
3. Mechanism in Photocatalytic Degradation: Where is the Figure 11? The article seems incomplete.”
Reply: We apologize for the oversight regarding Figure 11 in the manuscript. It appears that Figure 11, which is intended to, was inadvertently omitted from the submitted manuscript. In the revised manuscript on page 12, we added the missing Figure as “Figure 12” which depicts the thought of the MO photocatalytic degradation mechanism using pure Fe2O3 and carbon-modified Fe2O3@C nanoparticles.
Thank you for your valuable feedback.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have done a pretty good job of reworking the paper
and I am satisfied with most of the responses to my comments. Iron oxide also takes part in the generation of hydroxyl radicals. At the same time, the authors, when discussing the mechanism of oxidation of methyl orange, paid attention only to the photocatalytic process. You can use this literature when discussing the mechanism of heterogeneous photo-Fenton-like oxidation of organic dyes
https://0-doi-org.brum.beds.ac.uk/10.1016/j.inoche.2024.112563
https://0-doi-org.brum.beds.ac.uk/10.1007/s10311-021-01185-z
https://0-doi-org.brum.beds.ac.uk/10.1002/slct.202301694
https://0-doi-org.brum.beds.ac.uk/10.3390/catal13050872
https://0-doi-org.brum.beds.ac.uk/10.1016/j.jece.2022.108329
https://0-doi-org.brum.beds.ac.uk/10.1002/slct.202201382
In Fig. 6, 7 and 8, the curves need to be highlighted in a different color. So that it is easy to recognize with H2O2 and without H2O2
Author Response
1- The authors have done a pretty good job of reworking the paper and I am satisfied with most of the responses to my comments. Iron oxide also takes part in the generation of hydroxyl radicals. At the same time, the authors, when discussing the mechanism of oxidation of methyl orange, paid attention only to the photocatalytic process. You can use this literature when discussing the mechanism of heterogeneous photo-Fenton-like oxidation of organic dyes
https://0-doi-org.brum.beds.ac.uk/10.1016/j.inoche.2024.112563
https://0-doi-org.brum.beds.ac.uk/10.1007/s10311-021-01185-z
https://0-doi-org.brum.beds.ac.uk/10.1002/slct.202301694
https://0-doi-org.brum.beds.ac.uk/10.3390/catal13050872
https://0-doi-org.brum.beds.ac.uk/10.1016/j.jece.2022.108329
https://0-doi-org.brum.beds.ac.uk/10.1002/slct.202201382
Reply: Thank you for your positive feedback and for acknowledging the improvements made in our revised manuscript. We appreciate your valuable insights and suggestions, particularly regarding the role of iron oxide in the generation of hydroxyl radicals and the mechanism of oxidation of methyl orange. We modified the text in the introduction (page 2) to highlight the importance of heterogeneous photo-Fenton-like oxidation reactions and cited the most relevant recommended literature [21-25]. In addition, the photo-Fenton-like mechanism was elaborated in the discussion on page 11. Moreover, the “Photo-Fenton catalytic” expression has been added to the title and highlighted in yellow.
- In Fig. 6, 7, and 8 the curves need to be highlighted in a different color. So that it is easy to recognize with H2O2 and without H2O2.”
Thank you for your valuable feedback and for pointing out the need for clearer Figures 6, 7, and 8. In compliance with this comment, we have redrawn Fig. 6, 7, and 8, in addition to Fig. 11 to enhance clarity by using distinct colours for the curves representing experiments with and without Hâ‚‚Oâ‚‚. Thank you once again for your constructive comments.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe revised manuscript addressed the queries of the reviewer and well written. It could be accepted now
Author Response
1- The revised manuscript addressed the queries of the reviewer and well written. It could be accepted now.
Reply: many thanks for your positive feedback and acceptance of the manuscript.
