The Promoting Effect of Metal Vacancy on CoAl Hydrotalcite-Derived Oxides for the Catalytic Oxidation of Formaldehyde
Round 1
Reviewer 1 Report
This work reported CoAl hydrotalcite derived oxides for catalytic oxidation of gaseous formaldehyde. The novelty is fair, but the characterizations and in-depth discussion are lack. I recommend this manuscript need to be further enhanced.
1. The abbreviations like CoAl-LDH, CoAl-LDO and E5-LDO etc, should be provided the full name when they first appear in the text.
2. The typos for example line 206 page 5, and line 333 page 9 should be corrected.
3. In line 332 page 9, the explanation related to O1s is confused.
4. Can any other proof of the Al vacancy be offered? Additionally, the oxygen defects could be further characterized using the EPR technique.
5. What is the role of Co2+ in the oxidation of HCHO? How to prove it?
6. Why did the H2-TPR patterns of LDO and Ex-LDO differ greatly from those of LDO/NF and Ex-LDO/NF? What’s more, the HCHO conversion performance of LDO/NF and Ex-LDO/NF seemed inferior to those of LDO and Ex-LDO, which is inconsistent with the H2-TPR result.
7. Fig. 7 could be removed since it seemed meaningless in the text.
Author Response
Dear Editor and Reviewers:
On behalf of my co-authors, we thank you very much for giving us an opportunity to revise our manuscript. We appreciate editor and reviewers very much for their positive and constructive comments and suggestions on our manuscript entitled“Promoting effect of metal vacancy on CoAl hydrotalcite derived oxides for the catalytic oxidation of formaldehyde”(processes-2498643). We are very sorry to update the revised manuscript so late because the adding of some necessary literature to support our view.
In this revised version, we have addressed the concerns of the reviewers. An item-by-item response to the reviewers' comments is enclosed, and the revision was marked in red fonts in the manuscript. We hope that these revisions successfully address your concerns and requirements and that this manuscript will be accepted. Looking forward to hearing from you soon.
Best wishes.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Journal: processes
Manuscript number: processes-2498643
Title: Promoting effect of metal vacancy on CoAl hydrotalcite derived oxides for the catalytic oxidation of formaldehyde
The paper is interesting although some issues should be addressed before publication. Major revision is suggested to further improve its quality. Specific suggestions are provided below.
1. What are the advantages of Layered double hydroxides? (Applied Catalysis B: Environmental 2020. 273: 119051 and Separation and Purification Technology 2023, 312: 123412 may help and recommended to be cited)
2. What is the biggest flash point in this article should be provided in the introduction?
3. The abstract and introduction need to be rewritten. The introduction is not focused enough and the texts are too few.
4. Did the author do a parallel experiment?
5. Figure 7 could be further refined.
Author Response
Dear Editor and Reviewers:
On behalf of my co-authors, we thank you very much for giving us an opportunity to revise our manuscript. We appreciate editor and reviewers very much for their positive and constructive comments and suggestions on our manuscript entitled“Promoting effect of metal vacancy on CoAl hydrotalcite derived oxides for the catalytic oxidation of formaldehyde”(processes-2498643). We are very sorry to update the revised manuscript so late because the adding of some necessary literature to support our view.
In this revised version, we have addressed the concerns of the reviewers. An item-by-item response to the reviewers' comments is enclosed, and the revision was marked in red fonts in the manuscript. We hope that these revisions successfully address your concerns and requirements and that this manuscript will be accepted. Looking forward to hearing from you soon.
Best wishes.
Author Response File: Author Response.pdf
Reviewer 3 Report
The authors discuss an interesting method of modifying the properties, including activity in formaldehyde oxidation, of the surface of a catalytic system. The catalyst is synthesized using a nickel foam onto which the support is deposited and subsequently etched to obtain metal ion vacancies. In general, the manuscript is logical, the experiments are well-designed, but the discussion and interpretation of the results requires more work. Therefore, I recommend the publication of the manuscript after a major revision.
The authors state that the etching was performed with KOH (line 153), yet in the results of Figure 1 NaOH is mentioned as the etching agent (line 241) and again in lines 261, 268, 288. This requires an explanation.
There are no EDS maps nor numbers for the powdered catalysts, which exhibit a higher activity! The authors state that the difference in loading might be the reason for the difference, but show no numerical proof. Moreover, the XRD results seem to indicate that the more probable reason is the difference in the crystallinity of the active phase.
EDS is not a technique which is reproducible to the second decimal place of a wt.%. The results show a fairly constant amount of cobalt on the surface (18±2wt.%). The number of decimal values should be reduced to one. Similarly, providing 3 decimal places for the specific surface area is an exaggeration.
There does not seem to be a visible difference in the XRD patterns before and after etching as the authors suggest. If this can be seen at a larger magnification of the diffraction patterns in Figure 2a, please provide an insert where this is visible or do not write that the difference can be seen in the text.
The surface area of E5-LDO should also be provided. Since the activity results show a trend and the authors attribute this trend to the formation of metal vacancies upon etching, there should be a trend in the surface areas of the samples.
Please provide the details about the nickel foam used: what purity, which company it was bought from, etc.
Author Response
Dear Editor and Reviewers:
On behalf of my co-authors, we thank you very much for giving us an opportunity to revise our manuscript. We appreciate editor and reviewers very much for their positive and constructive comments and suggestions on our manuscript entitled“Promoting effect of metal vacancy on CoAl hydrotalcite derived oxides for the catalytic oxidation of formaldehyde”(processes-2498643). We are very sorry to update the revised manuscript so late because the adding of some necessary literature to support our view.
In this revised version, we have addressed the concerns of the reviewers. An item-by-item response to the reviewers' comments is enclosed, and the revision was marked in red fonts in the manuscript. We hope that these revisions successfully address your concerns and requirements and that this manuscript will be accepted. Looking forward to hearing from you soon.
Best wishes.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I am still confused that the HCHO conversion performance of LDO/NF and Ex-LDO/NF seemed inferior to those of LDO and Ex-LDO. However, as the authors stated that the ratios of Co2+/Co3+ and Oads/Olatt for LDO/NF and Ex-LDO/NF are higher than those of LDO and Ex-LDO (Table 2). Moreover, LDO/NF and Ex-LDO/NF show obviously lower reduction-peak temperature (below 400 °C) than E1-LDO and E5-LDO in H2-TPR curves. The characterization and performance results seem contradictory. Moreover, since the performances of LDO/NF and Ex-LDO/NF are worse than LDO and Ex-LDO, why do the authors still choose NF substrate?
Author Response
Dear Editor and Reviewers:
On behalf of my co-authors, we thank you very much for giving us an opportunity to revise our manuscript. We appreciate editor and reviewers very much for their positive and constructive comments and suggestions on our manuscript entitled“Promoting effect of metal vacancy on CoAl hydrotalcite derived oxides for the catalytic oxidation of formaldehyde”(processes-2498643). We are very sorry to update the revised manuscript so late because the adding of some necessary literature to support our view.
In this revised version, we have addressed the concerns of the reviewers. An item-by-item response to the reviewers' comments is enclosed. We hope that these revisions successfully address your concerns and requirements and that this manuscript will be accepted. Looking forward to hearing from you soon.
Best wishes.
Author Response File: Author Response.pdf
Reviewer 2 Report
accepted
Author Response
Dear Editor and Reviewer:
On behalf of my co-authors, I would like to reiterate my sincere gratitude for your letter and the constructive comments made by the reviewer on our article entitled “Promoting effect of metal vacancy on CoAl hydrotalcite derived oxides for the catalytic oxidation of formaldehyde”(processes-2498643), which were valuable and helpful in improving our article.
Finally, we sincerely thank you for accepting our article.
Best wishes.
Reviewer 3 Report
The manuscript has been revised in accordance with the suggestions provided to the authors and should be accepted for publication in the present form.
Author Response
Dear Editor and Reviewer:
On behalf of my co-authors, I would like to reiterate my sincere gratitude for your letter and the constructive comments made by the reviewer on our article entitled “Promoting effect of metal vacancy on CoAl hydrotalcite derived oxides for the catalytic oxidation of formaldehyde”(processes-2498643), which were valuable and helpful in improving our article.
Finally, we sincerely thank you for accepting our article.
Best wishes.
