Engineered 2D Metal Oxides for Photocatalysis as Environmental Remediation: A Theoretical Perspective
Round 1
Reviewer 1 Report
This mini-review entitled “Engineered 2D Metal Oxides for Environmental Remediation: A Theoretical Perspective” covers the latest developments in materials for numerous catalysis applications for environmental remediation by taking into account the unique electronic properties of 2D metal oxides. More specifically, this review focuses on the defects-rich structures of different 2D metal oxides by purposely creating the anion and cation vacancies. The first section i.e. introduction part is well written and the concepts are explained according to the current understanding in the field. This review also discussed some important research articles, as well as the data and conclusions from the cited references, are presented well. Similarly, in the other discussed sections, some of the results are interpreted in an organized way. Since the review title includes a theoretical perspective, so it would have been better if section 3 “theoretical insights” is added with additional discussion. The overall quality of the review is good; however, many minor corrections need to be addressed very carefully.
1. A table may convey quantitative information better than text. So it will be helpful for readers to understand the difference in the performance of different engineered 2D metal oxides in tabular form.
2. Some of the results can be elaborated more instead of just writing the conclusion of the cited manuscript such as: On page 11, line 403# 2D RG has been incorporated with Bi2WO6 and g-C3N4 to form the BWO/RGO/CN-Z scheme heterojunction.
3. Figures 3 and 5 are actually the same. No need to repeat the same figures.
4. One of the major concerns is that almost all the figures are cited wrongly. Images do not match with the cited references such as: In figure 1 (a) synthesis scheme is adapted from reference 1, not from reference 4. Figure 2 all the images are adapted from reference 23, not from reference 24. Similarly, figure 6. Authors are advised to double-check all the figures whether adapted from the cited reference or not.
5. Page #13 line 436, the text of the last paragraph is not matching with the references cited. Reference 60 is about “carbon quantum dots-decorated ultrathin Bi2WO6 Nano-sheets” not about Bi2WO6/Ti3C2. Recheck the whole paragraph.
6. For section 4.3 H2 evolution, it would be better if some figures corresponding to the text are given. The 4.1 sub-heading is titled H2O oxidation and the 4.2 sub-heading is titled H2 evolution. It would be better if the author gives similar sub-headings i.e. either write O2 evolution and H2 evolution or write H2O oxidation and H2O reduction. Sub-heading 3.3 CO2 reduction, it should be 4.3
7. On page #7 line 247, reconsider the sentence, “Hydrogen with the largest energy density” Hydrogen has the highest calorific value as well as the highest energy content of any common fuel by weight and lowest energy content by volume.
8. Page #3 line 82, Ti0.91O20.36 recheck the reference.
9. Page #4 line 115, N-atoms stretching (1.078-1.133), give proper unit like (1.078-1.133Å). Similarly, on page #5 line 145, it should be In2O3 not InO3.
Author Response
This mini-review entitled “Engineered 2D Metal Oxides for Environmental Remediation:
A Theoretical Perspective” covers the latest developments in materials for numerous
catalysis applications for environmental remediation by taking into account the unique
electronic properties of 2D metal oxides. More specifically, this review focuses on the
defects-rich structures of different 2D metal oxides by purposely creating the anion and
cation vacancies. The first section i.e. introduction part is well written and the concepts are
explained according to the current understanding in the field. This review also discussed
some important research articles, as well as the data and conclusions from the cited
references, are presented well. Similarly, in the other discussed sections, some of the results
are interpreted in an organized way. Since the review title includes a theoretical perspective,
so it would have been better if section 3 “theoretical insights” is added with additional
discussion. The overall quality of the review is good; however, many minor corrections need
to be addressed very carefully.
1. A table may convey quantitative information better than text. So it will be helpful for
readers to understand the difference in the performance of different engineered 2D metal
oxides in tabular form.
A: Table has been incorporated. (Please see table 1)
2. Some of the results can be elaborated more instead of just writing the conclusion of the
cited manuscript such as: On page 11, line 403# 2D RG has been incorporated with
Bi2WO6 and g-C3N4 to form the BWO/RGO/CN-Z scheme heterojunction.
A: Thanks for suggestion, we have revised all paragraphs accordingly.
3. Figures 3 and 5 are actually the same. No need to repeat the same figures.
A: Sorry. We have deleted the Figure 5.
4. One of the major concerns is that almost all the figures are cited wrongly. Images do
not match with the cited references such as: In figure 1 (a) synthesis scheme is adapted from
reference 1, not from reference 4. Figure 2 all the images are adapted from reference 23, not
from reference 24. Similarly, figure 6. Authors are advised to double-check all the figures
whether adapted from the cited reference or not.
A: We are really sorry, now all the captions are updated with accurate references.
5. Page #13 line 436, the text of the last paragraph is not matching with the references
cited. Reference 60 is about “carbon quantum dots-decorated ultrathin Bi2WO6 Nano-sheets”
not about Bi2WO6/Ti3C2. Recheck the whole paragraph.
A: Sorry, we have updated all references.
6. For section 4.3 H2 evolution, it would be better if some figures corresponding to the
text are given. The 4.1 sub-heading is titled H2O oxidation and the 4.2 sub-heading is titled
H2 evolution. It would be better if the author gives similar sub-headings i.e. either write
O2 evolution and H2 evolution or write H2O oxidation and H2O reduction. Sub-heading 3.3
CO2 reduction, it should be 4.3
A: Figure has been added in section “H2 evolution” (Please see figure 5 and 6). And all the
sub-heading has been checked.
7. On page #7 line 247, reconsider the sentence, “Hydrogen with the largest energy
density” Hydrogen has the highest calorific value as well as the highest energy content of any
common fuel by weight and lowest energy content by volume.
A: Many thanks for the suggestion. It has been changed to “Hydrogen with the highest
calorific value and the highest energy content by weight”.
8. Page #3 line 82, Ti0.91O20.36 recheck the reference.
A: Thanks for suggestion, reference has been updated
9. Page #4 line 115, N-atoms stretching (1.078-1.133), give proper unit like
(1.078-1.133Å). Similarly, on page #5 line 145, it should be In2O3 not InO3.
A: It is our mistake. It is done.
Reviewer 2 Report
The authors attempted to review scientific work in relation to 2D materials, most metal oxides with either anion or cation vacancies within their structures. The work touches on the fabrication of the materials and their application in environmental remediation reactions in the form of water splitting, hydrogen evolution etc. However, the work is insufficient for publication in Catalysts. Below are some of the most important comments:
1. Review on methods/routes on inducing vacancies, either anionic or cationic vacancies are not well explained. The authors need to explicitly review these.
2. There is not indepth comparison of the 2D materials to other materials for the reactions reviewed (H2 evolution, water splitting, CO2 reduction). A comparative study will highlight the advantages and the short-comings of the 2D materials. This will then make it easy to draw conclusions and future trends for these materials.
3. Furthermore, there are many other environmental remediation reactions. Why only focus on a few. There are other materials that can do a better job in terms of catalysis (photocatalysis) and they are not mentioned in the review.
4. There are many inconsistencies in the manuscript. The authors keep interchanging between "XXX and colleagues", "XXX and associates", "XXX and coworkers" and XXX et al. The authors must choose one from these and stick to it throughout the manuscript.
5. In line 151 "......Vo-doped..." Are the authors here refering to induced Vo in In2O3?
6. Line 178: ".....may cause to introduce....". The authors need to rephrase this sentence for it to make sense.
7. The dots in formulae of many materials needs to be corrected. for example, in line 200 the dot before the H2O is bold and must be corrected.
8. Line 311, the sentence is incomplete.
9. Line 443, "shorted" must be changed to shortened.
10. line 365, CO is not a fuel. This needs to be corrected.
Author Response
The authors attempted to review scientific work in relation to 2D materials, most metal oxides with either anion or cation vacancies within their structures. The work touches on the fabrication of the materials and their application in environmental remediation reactions in the form of water splitting, hydrogen evolution etc. However, the work is insufficient for publication in Catalysts. Below are some of the most important comments:
- Review on methods/routes on inducing vacancies, either anionic or cationic vacancies are not well explained. The authors need to explicitly review these.
A: Vacancies section has been updated please see heading 2.3
- There is not indepth comparison of the 2D materials to other materials for the reactions reviewed (H2 evolution, water splitting, CO2 reduction). A comparative study will highlight the advantages and the short-comings of the 2D materials. This will then make it easy to draw conclusions and future trends for these materials.
A: Superiority of 2D materials as compared to other has been disused in details, please see heading 1.1.
- Furthermore, there are many other environmental remediation reactions. Why only focus on a few. There are other materials that can do a better job in terms of catalysis (photocatalysis) and they are not mentioned in the review.
A: Although there are many environmental remediation reactions and materials, we used only a few reactions with a few 2D materials, based on our research background and interest. Contrarily, it is a mini-review, and we were not able to discuss all environmental remediations with all 2D materials..
There are many inconsistencies in the manuscript. The authors keep interchanging between "XXX and colleagues", "XXX and associates", "XXX and coworkers" and XXX et al. The authors must choose one from these and stick to it throughout the manuscript.
A: Many thanks for the suggestions. We have changed them to “XXX et al” throughout the manuscript.
- In line 151 "......Vo-doped..." Are the authors here refering to induced Vo in In2O3?
A: It is done.
Line 178: ".....may cause to introduce....". The authors need to rephrase this sentence for it to make sense.
A: It is done.
- The dots in formulae of many materials needs to be corrected. for example, in line 200 the dot before the H2O is bold and must be corrected.
A: It is done.
- Line 311, the sentence is incomplete.
A: All paragraphs and lines has been revised.
- Line 443, "shorted" must be changed to shortened.
A: It is done.
- line 365, CO is not a fuel. This needs to be corrected.
A: It is done.
Reviewer 3 Report
This mini review focuses on the theoretical perspective for the engineered two-dimensional (2D) metal oxides in photocatalysis for environmental remediation, including the photocatalytic H2O oxidation, H2 evolution and CO2 reduction reaction. The application of 2D metal oxides in photocatalysis has been found to exhibit exceptional photocatalytic performance and attracts increasingly attentions for the application in environmental remediation. The authors summarized recent developments for this fields. However, authors did not provide enough perspectives for the future directions for developing more practical photocatalyst.
1, This mini review mainly focuses on photocatalysis. The current title does not provide any information about the photocatalysis. It’s suggested that the title updated to ‘Engineered 2D Metal Oxides for Photocatalysis in Environmental Remediation: A Theoretical Perspective’.
2, Lots of abbreviations could not be found their full name in the review. For example, Page 2, line 58, AFM; page 4, line 117, Vo; page 4, line 127-133, XRD, XPS, TEM, etc. The authors should double check their use of abbreviations and provide the corresponding full name at first appearance.
3, It is suggested that authors provided an illustration for current challenges in photocatalysis theoretically and experimentally in Section 3.
4, It is suggested that authors provided the corresponding mechanisms for photocatalysis in H2O oxidation (Section 4.1), H2 evolution (Section 4.2), CO2 reduction (Section 4.3). For example, the authors mentioned the slow dynamics of the 4-hole half-reaction mechanism in water oxidation, it will be better for readers to understand if the authors provided corresponding mechanisms with chemical equations.
5, page 10, line 362, ‘3.3 CO2 reduction’ should be corrected to ‘4.3 CO2 reduction’.
6, The author can also choose to merge Section 3 and Section 4, both seem to provide theoretical reviews for environmental remediation.
Author Response
This mini review focuses on the theoretical perspective for the engineered two-dimensional
(2D) metal oxides in photocatalysis for environmental remediation, including the
photocatalytic H2O oxidation, H2 evolution and CO2 reduction reaction. The application of
2D metal oxides in photocatalysis has been found to exhibit exceptional photocatalytic
performance and attracts increasingly attentions for the application in environmental
remediation. The authors summarized recent developments for this fields. However, authors
did not provide enough perspectives for the future directions for developing more practical
photocatalyst.
1, This mini review mainly focuses on photocatalysis. The current title does not provide any
information about the photocatalysis. It’s suggested that the title updated to ‘Engineered 2D
Metal Oxides for Photocatalysis in Environmental Remediation: A Theoretical Perspective’.
A: Many thanks for the suggestion. It is done.
2, Lots of abbreviations could not be found their full name in the review. For example, Page 2,
line 58, AFM; page 4, line 117, Vo; page 4, line 127-133, XRD, XPS, TEM, etc. The authors
should double check their use of abbreviations and provide the corresponding full name at
first appearance.
A: Many thanks for the suggestion. It is done.
3, It is suggested that authors provided an illustration for current challenges in photocatalysis
theoretically and experimentally in Section 3.
A: All the possible challenges and suggestion are addressed in section 4 (this whole section is
revised).
4, It is suggested that authors provided the corresponding mechanisms for photocatalysis in
H2O oxidation (Section 4.1), H2 evolution (Section 4.2), CO2 reduction (Section 4.3). For
example, the authors mentioned the slow dynamics of the 4-hole half-reaction mechanism in
water oxidation, it will be better for readers to understand if the authors provided
corresponding mechanisms with chemical equations.
A: Thanks for nice suggestion, all the mechanisms have been incorporated in their respective
sections.
5, page 10, line 362, ‘3.3 CO2 reduction’ should be corrected to ‘4.3 CO2 reduction’.
A: It is done.
6, The author can also choose to merge Section 3 and Section 4, both seem to provide
theoretical reviews for environmental remediation.
A: It is done.
Round 2
Reviewer 2 Report
The authors revised the manuscript, and it is now of an accepted standard to be published in Catalysts
