Exceptional Photocatalytic Performance of the LaFeO3/g-C3N4 Z-Scheme Heterojunction for Water Splitting and Organic Dyes Degradation
Round 1
Reviewer 1 Report
The authors reported LaFeO3/g-C3N4 as a Z-scheme system for water reduction to produce hydrogen and organic dye degradation under visible light irradiation. The exceptional performance of the LaFeO3/g-C3N4 Z-scheme catalyst could be due to remarkably enhanced charge carrier separation and improved light absorption. So, this work is interesting and suitable for publication in Catalysts after minor revision.
(1) How to confirm the formation of Z-scheme structure?
(2) The exact loading amount of LaFeO3 on g-C3N4 should be considered.
(3) Figure 4c, the equivalent circuit should be given.
(4) Some grammar errors should be corrected before publication.
Author Response
Author's Reply to the Review Reports (Reviewer 1)
Reviewer 1
The authors reported LaFeO3/g-C3N4 as a Z-scheme system for water reduction to produce hydrogen and organic dye degradation under visible light irradiation. The exceptional performance of the LaFeO3/g-C3N4 Z-scheme catalyst could be due to remarkably enhanced charge carrier separation and improved light absorption. So, this work is interesting and suitable for publication in Catalysts after minor revision.
Response: Respected reviewer, thanks for recognizing the potential significance of our manuscript. We have carefully revised the whole manuscript and improved as per the reviewer’s comments/suggestions. Changes made in the revised manuscript has been highlighted in yellow.
(1) How to confirm the formation of Z-scheme structure?
Response: Thanks for the valuable question. A Z-scheme semiconductor heterojunction is a type of junction where electrons transfer from one semiconductor to another via an intermediate redox couple. Confirming a semiconductor-semiconductor Z-scheme composite involves verifying that the composite accurately represents the electron transfer between two semiconductor materials during the process of photocatalysis. Before we can confirm a semiconductor-semiconductor Z-scheme composite, we need to have a good understanding of how the Z-scheme works in the context of photocatalysis. This includes understanding the different semiconductors and electron carriers involved in the process. Analyzing the data obtained from valence band XPS measurement to determine whether the energy band diagram of the heterojunction corresponds to a Z-scheme. EPR test during photocatalysis is further used to confirm Z-scheme mechanism via the generation of reactive oxygenate species such as •OH, •O2‒, etc.
(2) The exact loading amount of LaFeO3 on g-C3N4 should be considered.
Response: Thanks for the valuable question. The exact loading amount of LaFeO3 in the LaFeO3/g-C3N4 composite was 5 wt.% as highlighted in yellow in the revised manuscript.
(3) Figure 4c, the equivalent circuit should be given.
Response: Thanks for the valuable suggestion. The equivalent circuit has been provided as inset in Figure 4c.
(4) Some grammar errors should be corrected before publication.
Response: Thanks for the valuable suggestion. The whole manuscript has been carefully revised and corrections have been made where necessary as highlighted in yellow in the revised manuscript.
Reviewer 2 Report
Dear Editor,
Thanks for inviting me for review the manuscript entitled Exceptional Photocatalytic Performance of the LaFeO3/g-C3N4 Z-Scheme Heterojunction for Water Splitting and Organic Dyes Degradation authored by Muhammad Humayun and Mohamed Bououdina, et al.
The work reports photocatalytic hydrogen production using a heterojunction catalyst of LaFeO3/g-C3N4, also the application of the material to pollutant degradation was explored.
The structural, electronic, and elemental features of the material has been properly characterized and provided, the performance of hydrogen production and pollutant degradation have also been tested. The mechanism of photocatalysis has been proposed based on the EPR results. However, there are still some issues to be addressed to make the manuscript more complete before accepting by Catalysts.
1) The introduction part should state the importance of heterojunctional photocatalysts, accompanying by some examples for application of water splitting & hydrogen production & pollutant degradation. It is suggested to cite some recent literatures to enhance the understanding on the objective of this work. For example, J. Phys. Chem. Lett. 2014, 5, 12, 2101–2107; International journal of hydrogen energy 45 (2020) 15985-16038; Adv.Mater.2017, 29, 1601694; Materials Research Bulletin, 2022, 147, 111636.
2) The profiles of degradation rate as a function of time for on RhB and MB should be given, also, the dark adsorption experiments should be carried out to exclude that the removal of dyes were not due to adsorption.
3) The radical trapping experiments on hydroxyl and superoxide anion radicals should be provided to confirm their contribution to the degradation.
Author Response
Author's Reply to the Review Reports (Reviewer 2)
Reviewer 2
Thanks for inviting me for review the manuscript entitled Exceptional Photocatalytic Performance of the LaFeO3/g-C3N4 Z-Scheme Heterojunction for Water Splitting and Organic Dyes Degradation authored by Muhammad Humayun and Mohamed Bououdina, et al. The work reports photocatalytic hydrogen production using a heterojunction catalyst of LaFeO3/g-C3N4, also the application of the material to pollutant degradation was explored. The structural, electronic, and elemental features of the material has been properly characterized and provided, the performance of hydrogen production and pollutant degradation have also been tested. The mechanism of photocatalysis has been proposed based on the EPR results. However, there are still some issues to be addressed to make the manuscript more complete before accepting by Catalysts.
Response: Respected reviewer, thanks for recognizing the potential significance of our manuscript. We have carefully revised the whole manuscript and improved as per the reviewer’s comments/suggestions. Changes made in the revised manuscript has been highlighted in yellow.
1) The introduction part should state the importance of heterojunctional photocatalysts, accompanying by some examples for application of water splitting & hydrogen production & pollutant degradation. It is suggested to cite some recent literatures to enhance the understanding on the objective of this work. For example, J. Phys. Chem. Lett. 2014, 5, 12, 2101–2107; International journal of hydrogen energy 45 (2020) 15985-16038; Adv.Mater.2017, 29, 1601694; Materials Research Bulletin, 2022, 147, 111636.
Response: Thanks for the valuable suggestion. Detail about the heterojunction photocatalysts has been provided in the introduction part and the suggested references have been cited accordingly as highlighted in yellow.
2) The profiles of degradation rate as a function of time for on RhB and MB should be given, also, the dark adsorption experiments should be carried out to exclude that the removal of dyes were not due to adsorption.
Response: Thanks for the valuable suggestion. The profiles of degradation rate as a function of time for RhB and MB along with the dark adsorption experiments have been provided in the revised manuscript as highlighted in yellow.
3) The radical trapping experiments on hydroxyl and superoxide anion radicals should be provided to confirm their contribution to the degradation.
Response: Thanks for the valuable suggestion. The radical trapping experiments have been carried out and the results are included in the revised manuscript as highlighted in yellow.
Reviewer 3 Report
The manuscript entitled: “Exceptional Photocatalytic Performance of the LaFeO3/g-C3N4 Z-Scheme Heterojunction for Water Splitting and Organic Dyes Degradation" is an interesting topic for journal readers. The article is well written but only needs "Minor Revision" considering the following comments before publication. This manuscript should be considered for publication after the consideration of the following questions:
1. There are some typos in the manuscript. The number of “LaFeO3” and “C3N4” should be subscript. (page 2, line 82; page 5, line 164; page 6, line 215)
2. Some related to the latest literature should be updated:
l doi.org/10.3762/bjnano.13.79
l doi.org/10.1021/acssuschemeng.2c01138
l doi.org/10.1016/j.jtice.2022.104357
l doi.org/10.1016/j.jtice.2022.104476
3. The author could use dashed lines or descript the exploration of the valence band XPS spectra in detail. Meanwhile, the related reference should be cited.
4. The author should illustrate the consecutive photocatalytic recycles in section of 3.5.
Author Response
Author's Reply to the Review Reports (Reviewer 3)
Reviewer 3
The manuscript entitled: “Exceptional Photocatalytic Performance of the LaFeO3/g-C3N4 Z-Scheme Heterojunction for Water Splitting and Organic Dyes Degradation" is an interesting topic for journal readers. The article is well written but only needs "Minor Revision" considering the following comments before publication. This manuscript should be considered for publication after the consideration of the following questions:
Response: Respected reviewer, thanks for recognizing the potential significance of our manuscript. We have carefully revised the whole manuscript and improved as per the reviewer’s comments/suggestions. Changes made in the revised manuscript has been highlighted in yellow.
- There are some typos in the manuscript. The number of “LaFeO3” and “C3N4” should be subscript. (page 2, line 82; page 5, line 164; page 6, line 215)
Response: Thanks for the valuable comment. The whole manuscript has been carefully revised and corrections have been made where necessary as highlighted in yellow in the revised manuscript.
- Some related to the latest literature should be updated:
l doi.org/10.3762/bjnano.13.79
l doi.org/10.1021/acssuschemeng.2c01138
l doi.org/10.1016/j.jtice.2022.104357
l doi.org/10.1016/j.jtice.2022.104476
Response: Thanks for the valuable suggestion. The literature has been updated with the suggested references.
- The author could use dashed lines or descript the exploration of the valence band XPS spectra in detail. Meanwhile, the related reference should be cited.
Response: Thanks for the valuable suggestion. We have represented the valence band XPS spectra with dashed lines and also cited relevant references.
- The author should illustrate the consecutive photocatalytic recycles in section of 3.5.
Response: Thanks for the valuable suggestion. The consecutive photocatalytic recycles have been illustrated in section 3.5 accordingly as highlighted in yellow.
Round 2
Reviewer 2 Report
The authors revised the manuscript raised by the reviewer, thus it can be accepted by addressing the only one issue regarding the reference format.
- reference 8, lack of the publishing year.
Author Response
Response: Thanks for directing us toward this mistake. Publishing year has been added to reference number 8.
