Synthesis of Ni@SiC/CNFs Composite and Its Microwave-Induced Catalytic Activity
Round 1
Reviewer 1 Report
The authors presented a complex Ni@SiC/CNF nanocomposite for their application as dye degradation catalysts. The materials were thoroughly characterized with SEM, TEM, XRD, Raman, and XPS and compared with the individual components prepared by the same method. The prepared nanocomposite showed good catalytic efficiency in the presence of electromagnetic energy. The electromagnetic wave absorption and degradation characteristics of the nanocomposite were elucidated to understand the catalytic mechanisms. However, the detailed comments have to be considered to improve the quality of the manuscript.
1. There are multiple incomplete sentences in the manuscript. A thorough proofreading is recommended. For instance, lines 99-101 on pages 2 and 3.
2. The operational parameters used for electrospinning should be provided in the experimental section.
3. Instrumental details of Raman spectroscopy should be provided.
4. On page 4, lines 160-161 are confusing. Why would the diffraction peak of SiC of the SC catalyst be lower?
5. If graphitization is deduced from G band intensity, why does the higher R-value indicate higher graphitization?
6. On page 4, line 174, the phrase “which corresponds to the XRD results” should be modified to “agrees with the XRD results”.
7. On page 6, line 211, the sentence “This is mainly due to ….” is not clear. Does C and Si diffuse into the molten Ni? If they diffuse, how does it form a core@shell kind of structure as represented in the schematic by the authors?
8. how much difference is there between the precipitation temperature of SiC and C? Have the authors tried to analyse the impact of temperature during the sample preparation?
9. Scale bars in Fig 5 are not clear.
10. How is the reflection loss measured? The details should be provided in the experimental section.
Author Response
Please see the attachment. Thank you for your understanding!
Author Response File: 
Author Response.pdf
Reviewer 2 Report
1. The author synthesized Ni@SiC/CNFs using the electrostatic spinning method. Why did the author choose this technique, and how does it compare to other synthesis methods in terms of benefits?
2. Among the variety of dyes available, the author selected MB dyes for degradation. The rationale behind this specific choice needs clarification.
3. The author must analyze the reusability of the prepared samples. Additionally, the structure and functional groups of the prepared samples should be analyzed in both fresh and recycled photocatalysts.
4. The author should describe the byproducts formed after the completion of the photocatalytic activity of the dyes.
5. The authors are required to provide the results of electrochemical impedance spectroscopy (EIS) and transient photocurrent response. Additionally, they should discuss the charge carrier transfer and separation ability of the photocatalyst.
6. What is the apparent quantum efficiency of the best photocatalyst?
1. In line 17, there is a typo error in the superoxide radical symbol. The author should correct it.
2. In the caption of Figure 1, there is a comma typo error. The author should correct it.
3. In Figure 2, XRD patterns, the hkl planes and the corresponding JCPDS file numbers should be added to the appropriate places.
4. On page 186, there are many formulas that need to be corrected throughout the manuscript.
Author Response
Please see the attachment. Thank you for your understanding!
Author Response File: Author Response.pdf
Reviewer 3 Report
This article investigates the preparation of carbon-based catalysts and their subsequent application for treating solutions containing methylene in combination with microwave irradiation.
This topic is of interest to the readers of this journal. However, the manuscript requires much work to improve the quality of the text before publication. I recommend major revisions.
1) Beyond the academic significance, the authors should emphasize the interest in developing such a process and the advantages over the already existing or proposed treatments considering that: i) the synthesis of the catalysts is complex and requires the use of hazardous reagents; ii) microwave irradiation adds further costs; iii) the molecule is only degraded and not mineralized; iv) a high catalysts-to-solution ratio is needed.
2) It is always advised that degradation by AOPs should not be followed by UV-vis analyses since hydroxylated by-products present similar maximum absorption to parent compounds and chromatographic analyses are required
3) Other missing aspects include the formation of potentially dangerous compounds, changes in toxicity (which could even increase after treatment), and the durability of the catalysts.
4) The involvement of the reported radicals should be confirmed by tests with selective scavengers or by EPR spectroscopy.
5) In the abstract: what did the authors mean with polarization source of the material?
6) The introduction is too long; presenting the state of the art more succinctly would make it more effective.
7) Please, report the concentration of the methylene solution in the materials and methods
8) Although the reached mineralization values are not particularly high, different ratios between the volume of solution to be treated to the grams of catalyst are not tested.
9) Why was that catalyst-to-solution ratio chosen, and why weren't different values investigated?
10) To investigate the synergy between the catalysts and microwave irradiation, it would be necessary to verify the degradation of the target molecule only with the catalysts and then only subjected to irradiation
A careful revision of the text is recommended. English should be checked carefully since the text contains some mistakes and typos (i. e. The unpair electron of hydroxyl radical must be reported on the oxygen and not on the hydrogen (·OH and not OH·); The superoxide anion radical must be reported as O2-·and not O2- ; Line 99: the sentence sounds wrong and must be revised)
Author Response
Please see the attachment. Thank you for your understanding!
Author Response File: Author Response.pdf
Reviewer 4 Report
Recommendation: Majeur Revision
Comments to the Author
The topic of the manuscript is appropriately suited for publication. The manuscript is in general well written and organized. It provides a large amount of experimental data, and the work seems to be carefully executed. The authors used appropriate methods to address the aims and objectives of the study. The results obtained are also interesting and relevant. Overall, the study is technically solid and includes appropriate methods as well as pertinent results. However, and for the sake of full impact only, the authors are invited to consider the following list of suggestions and recommendations.
The reviewer has some specific comments/suggestions provided below.
1. The introduction is quite dense and technical. While this is appropriate for a scientific audience, structuring the text to improve flow and clarity would be beneficial. Ensure that each paragraph logically leads to the next. Some passages seem to transition abruptly from one topic to another.
2. Section 2.1. Synthesis of Ni@SiC/CNFs: Please provide the full names of the materials when first mentioned in the synthesis section. For clarity, it is important to specify that CNFs refer to carbon nanofibers and SiC refers to silicon carbide. This will ensure that all readers, regardless of their familiarity with the abbreviations, can easily understand the materials being discussed.
3. In section 2.3, during the microwave-assisted degradation experiment, it is unclear what "50 mL" refers to. The authors are encouraged to specify the medium or solution into which the 20 mL of MB solution and 20 mg of catalyst were added. Additionally, it would be beneficial for the authors to mention the concentration of MB used in the experiment.
4. Drx results: I request that you calculate the crystallite size for each diffraction peak observed in your samples, particularly for the (002) carbon, (111) SiC, and (121) Ni peaks as identified in your XRD analysis. This will provide additional valuable information about the crystalline structure of your catalysts.
5. In section: 3.2. Microwave-induced catalytic degradation of MB: The authors provide a detailed presentation of experimental results without delving into a thorough interpretation or explanation of underlying mechanisms and interactions between the different materials. It is crucial to discuss more deeply the significance of the observed results, including proposed mechanisms for the superior catalytic activity of NSC compared to the other catalysts. A comprehensive analysis of synergistic interactions between the catalyst components (Ni, SiC, CNFs) could enhance understanding of the observed catalytic performances.
6. In the section on the degradation experiment using microwaves, it is recommended that the authors mention specific working conditions such as pH, temperature, etc. This will allow for better understanding and reproducibility of the experiment.
7. In Figure 8, it is unclear whether the title should refer to the "Degradation mechanism of Ni@SiC/CNFs composites under microwave irradiation" or the "Degradation mechanism of methylene blue with Ni@SiC/CNFs composites under microwave irradiation." Please clarify.
8. The description of the degradation mechanism is comprehensive, but it could benefit from clearer structure and more precise terminology. For example, the generation and role of "hot spots" should be explained in greater detail. While the text mentions the synergy between the components (C, Ni, SiC), it would be pertinent to provide more details on how each component specifically contributes to the improvement of degradation efficiency. The use of precise technical terms, such as "electron-hole pairs," would also enhance scientific rigor.
Overall, it is important to describe the mechanism in a coherent and logical manner, with smooth transitions between each point. The authors are also encouraged to include previous scientific references that have been used as a basis for understanding the degradation mechanism, to reinforce the credibility and depth of the analysis.
Author Response
Please see the attachment. Thank you for your understanding!
Round 2
Reviewer 3 Report
I think there is still some work to be done before publication. I recommend minor revisions
The authors left several observations unaddressed. I especially would like to insist on the request
1) to underline, even briefly, the advantage of the proposed treatment over the current state of knowledge.
2) To provide the blank tests, by verifying the degradation of the target molecule first using only the catalysts and then using only the irradiation. I understand that experimentation is at a preliminary stage but these tests are mandatory to clarify the process.
Moreover,
3) In the degradation experiment paragraph, the authors report “20 ml of methyl bromide” instead of methylene blue
4) At page 7, the authors report: “In addition, we performed free radical scavenging tests and cyclic degradation tests on NSC catalysts. As can be seen in Fig. 6(d), tert-butanol and sodium oxalate were added to the reaction solution as ·OH scavenger, O2-·scavenger, and H+ scavenger” but:
i) H+ is not a radical, probably the authors mean h+ which is a hole (and not a radical itself either). This mistake is repeated several times.
ii) It is unclear which scavenger is used to remove each specific species. Please specify better.
No comments
Author Response
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Reviewer 4 Report
Accept in present form
Accept in present form
Author Response
We sincerely appreciate your efforts in reviewing this manuscript and your valuable comments! We wish you all the best in your endeavors and a happy life!
Author Response File: Author Response.pdf
