CoNi₂O₄ Coated on Activated Carbon Wheat Husk (ACWH) as a Novel Nano-Electrocatalyst for Methanol and Ethanol Electro-Oxidation

Round 1

Reviewer 1 Report

The authors reported the synthesis of CoNi2O4 coated on activated carbon wheat husk (ACWH) as a novel nano-electrocatalyst for methanol and ethanol electrooxidation. Much data can support the conclusions. Therefore, I agree that it can be accepted for publication after minor revisions. The authors should address the following questions carefully.

1. The novelty of this work should be further highlighted in the Introduction.

2. The reaction mechanism should be presented.

3. Please compare the reported performance with the reported values.

4. The English writing should be improved.

5. Please provide the data to confirm the production after methanol and ethanol electrooxidation.

6. The following papers (ACS Applied Materials & Interfaces, 2022, 14, 47560-47567; Energy & Environmental Materials 2022, e12441; Applied Catalysis B: Environmental, 2023, 325, 122388) are recommended to be cited for improving the manuscript.

 

Author Response

The authors reported the synthesis of CoNi2O4 coated on activated carbon wheat husk (ACWH) as a novel nano-electrocatalyst for methanol and ethanol electrooxidation. Much data can support the conclusions. Therefore, I agree that it can be accepted for publication after minor revisions. The authors should address the following questions carefully.

Thank you for giving us this opportunity to revise and resubmit the manuscript. After considering your remarks carefully, we have carefully revised our manuscript. We are now sending the revised article in the submission system for your re-consideration to publish in the Coatings. The changes that we made in the revised manuscript are highlighted in Yellow for your easy reference. Our responses are as follows

1. The novelty of this work should be further highlighted in the Introduction.

Thanks for your attention, this point has been added in the text.

2. The reaction mechanism should be presented.

Thank you for your comment

We have proposed a 6-electron mechanism for methanol oxidation and a 12-electron mechanism for ethanol oxidation. In the first step, methanol/ethanol is absorbed on the surface and in the pores of the catalyst.

In the next step, methanol/ethanol absorbed in the presence of deprotonated hydroxyl ions (protons are separated) and some side products such as (CH₃O, CH₂O, CHO) and (CH₃CH₂O, CH₃CHO, CH₃CO^-) etc. are created in this step. In addition, hydroxyl ions are also adsorbed on the catalyst surface. In the last step, the surface of the catalyst is cleaned from the absorbed species and the catalyst works again in the oxidation process.

The mechanism of synthesis was also added to the text of the article.

 

3. Please compare the reported performance with the reported values.

Thank you for your comment

A comparison table was added to the article.

 

4. The English writing should be improved.

Thank you for your comment

We tried to improve the language of the article.

 

5. Please provide the data to confirm the production after methanol and ethanol electrooxidation.

 

Thank you for your comment.

  Adsorbed methanol/ethanol is deprotonated in the presence of hydroxyl ions and some side products such as (CH₃O, CH₂O, CHO) and (CH₃O, CH₂O, CHO), etc. are created in this step. In addition, hydroxyl ions are also adsorbed on the catalyst surface.

 

6. The following papers (ACS Applied Materials & Interfaces, 2022, 14, 47560-47567; Energy & Environmental Materials 2022, e12441; Applied Catalysis B: Environmental, 2023, 325, 122388) are recommended to be cited for improving the manuscript.

Thank you for your suggestion. References were added to the article.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper entitled “CoNi₂O₄ coated on activated carbon wheat husk (ACWH) as a novel nano-electrocatalyst for methanol and ethanol electrooxidation” synthesised a CoNi₂O₄ coated activated carbon through hydrothermal method as electrocatalyst for methanol and ethanol electrooxidation.

The results were reasonably analyzed and discussed. However, the present version can not be accepted. Comments and questions are as follows:

 

1. The novelty should be further emphasized in the Introduction. There are many active carbons that have been used as supports for catalyst synthesis. What’ is the novelty or superiority of wheat husk derived carbon, compared to those reported in literatures?

2. Please carefully checked the formation of units (e.g., mL, ℃) and the use of superscript and subscript.

3. The structure of manuscript shouted be reorganized. For instance, the setup of experiment, such as 3.5.1 Preparation of Electrode, should be moved to Section “2. Materials and Methods”.

channel structure", which was not fully supported by the follow-up data. More characterization and discussion are required.

4. The active carbons generally exhibit an apparent capacitance characteristics. A higher current density in CV curves (Fig. 6 and Fig. 7) was probably from the capacitance rather than alcohol/ methanol oxidation. It is suggested that the baseline current density of CV curves should be collected in the electrolyte without alcohol/methanol, and the net current density of alcohol/ methanol oxidation was plotted by subtracting the baseline current from total current density.

5. The electric conductivity and heteroatom doping of precursor were crucial factors affecting the overall performance of catalysts, it is better to compare the performance of electrocatalysts that were obtained at different temperatures.

6. X-ray photoelectron spectroscopy was suggested to elucidate the functional group, elements and their valence states on the surface of catalysts.

7. Authors mentioned that effective surface area in the catalyst improves the performance of the catalyst. As a porous material, active carbon usually exhibited a high specific surface area. It is suggested to provide the Brunauer–Emmett–Teller (BET) and the measurement of electrochemical active area (ECSA).

Author Response

The paper entitled “CoNi₂O₄ coated on activated carbon wheat husk (ACWH) as a novel nano-electrocatalyst for methanol and ethanol electrooxidation” synthesised a CoNi₂O₄ coated activated carbon through hydrothermal method as electrocatalyst for methanol and ethanol electrooxidation. The results were reasonably analyzed and discussed. However, the present version cannot be accepted. Comments and questions are as follows:

Thank you for giving us this opportunity to revise and resubmit the manuscript. After considering your remarks carefully, we have carefully revised our manuscript. We are now sending the revised article in the submission system for your re-consideration to publish in the Coatings. The changes that we made in the revised manuscript are highlighted in Yellow for your easy reference. Our responses are as follows

 

1. The novelty should be further emphasized in the Introduction. There are many active carbons that have been used as supports for catalyst synthesis. What’ is the novelty or superiority of wheat husk derived carbon, compared to those reported in literatures?

 

Thank you for your attention, one of the reasons for our use of wheat husk for carbon production is its abundance and availability, as well as the ease and low cost of producing biomass carbon from wheat husk waste compared to other materials, can be the most important reason for choosing this article stated. According to the studies, this type of catalyst, which includes binary metal oxide and biomass carbon, has not been used in the fuel cell anode.

 

2. Please carefully checked the formation of units (e.g., mL, ℃) and the use of superscript and subscript.

Thank you for your attention in reading the research text, the text was revised and your comments were applied.

3. The structure of manuscript shouted be reorganized. For instance, the setup of experiment, such as 3.5.1 Preparation of Electrode, should be moved to Section “2. Materials and Methods”.

Channel structure", which was not fully supported by the follow-up data. More characterization and discussion are required.

Thank you for your guidance, the structure of the article has been revised.

4. The active carbons generally exhibit an apparent capacitance characteristics. A higher current density in CV curves (Fig. 6 and Fig. 7) was probably from the capacitance rather than alcohol/ methanol oxidation. It is suggested that the baseline current density of CV curves should be collected in the electrolyte without alcohol/methanol, and the net current density of alcohol/ methanol oxidation was plotted by subtracting the baseline current from total current density.

Thank you for your comment. We have proven precisely what you mentioned in figures 7, 8, and 10. In Figure 7, the CV analysis of the catalysts was performed in the absence of methanol and ethanol. Figures 8 and 10, with the presence of methanol and ethanol alcohols (0.5 M potassium hydroxide solution was used in all analyses). Comparing the behavior of the catalysts in Figures 8 and 10 with Figure 7 shows the increase in oxidation current density. For this reason, this peak current density increase can be related to methanol and ethanol oxidation processes.

5. The electric conductivity and heteroatom doping of precursor were crucial factors affecting the overall performance of catalysts, it is better to compare the performance of electrocatalysts that were obtained at different temperatures.

Thank you for your very attractive offer. It was really a great idea for our research team. Unfortunately, it is not possible to synthesize the catalyst in the current period of time, as well as the closure of universities due to the New Year in Iran. Also, in this research, our goal was to improve the performance of catalysts by adding ACWH to their structure. Thanks again for your suggestion. We will definitely apply it in future researches.

6. X-ray photoelectron spectroscopy was suggested to elucidate the functional group, elements and their valence states on the surface of catalysts.

Thank you for your great comment. Unfortunately, for XPS analysis, we have to send the samples outside of Iran, which is not possible for us. This process takes several months.

1. Authors mentioned that effective surface area in the catalyst improves the performance of the catalyst. As a porous material, active carbon usually exhibited a high specific surface area. It is suggested to provide the Brunauer–Emmett–Teller (BET) and the measurement of electrochemical active area (ECSA).

Thank you for your opinion, BET analysis was added in the text and the obtained values were compared between the two catalysts. Unfortunately, due to the New Year holidays in Iran, it is not possible to use potentiostat

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The manuscript can be published after the format of references are well revised .

Reviewer 2 Report

No more comments