Tuning Photocatalytic Performance of Multilayer ZnO for Water Splitting by Biaxial Strain Composites
, Guangju Ji 1, Yunxiao Zhang 2, Zhendong Fu 2 and Changlong Tan 1Round 1
Reviewer 1 Report
In this paper, Cai and co-authors present DFT study on the electronic properties of multilayer ZnO (up to six layers). The change of the bandgap upon biaxial strain and the photocatalytic performance of ZnO for water spitting are also investigated. In my opinion the research is useful for clarification of the photocatalytic behavior of the modelled systems and will be of interest for the readers of Catalysts. I would recommend publication.
Author Response
Thanks for your favorite consideration and insightful comments about our manuscript. Your comments were enabled us to greatly improve the quality of our manuscript.
Reviewer 2 Report
Presented paper fulfills the Journal Scopus. The research objectives and results are clearly stated. The authors, motivated by cited literature, carried out experiments and confirmed known knowledge. In my opinion, the presented paper contributes significantly to the advancement of the research area.
Line 42 - the formula "dramatically improved" this expression is strong, should be modified, be lighter
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 3 Report
The manuscript “Tuning Photocatalytic performance of Multilayer ZnO for Water Splitting by Biaxial Strain Composites” by Xiaofan Cai et al. is a reasonably interesting investigation showing results of the quantum calculation for the band structure of the graphite-like layered ZnO depending on the in-plane strain. The authors demonstrated that the biaxial strain decreases the band gap, which contributes to the high efficiency of the water splitting through the ZnO photo-catalyst. Furthermore, they predicted that 6-layer ZnO under 1% strain gives the largest adsorption coefficient for the visible light among the strained and unstrained ZnOs with the 1-6 layers thickness.
Major revision
The manuscript so far lacks a quantitative discussion on the performance for the strained ZnO as the photo-catalytic material and an explanation of the gap narrowing mechanism. They should give the novel knowledge or deep understanding on the tuning of the photo-catalytic performance because it has been established that the water splitting efficiency is improved by applying the strain as they indicated in the references. For instance, it is much improved by showing the mechanism of the gap narrowing under the 1% strain in terms of the geometric arrangement of atoms.
Minor revisions
The title “Tuning Photocatalytic performance of Multilayer ZnO for Water Splitting by Biaxial Strain Composites”->“Tuning Photocatalytic Performance of Multilayer ZnO for Water Splitting by Biaxial Strain Composites”
Use the capital character for the initial of “Performance”.
Line 80 “Chen et al. tuned the bandgap of mono-layer ZnO via biaxial strain, they found that mono-layer ZnO at 10% has better photocatalytic water splitting performance [34].”
What does “at 10%” mean?
Line 124 “the bandgap of nL ZnO decreases for the quantum confinement and interaction between the interlayers.”
What does quantum confinement mean? Does the quantum confinement decrease the bandgap?
Line 127 “It can be predicted that as the number of layers continues to increase, the bandgap curve approaches a specific limit, which is precisely determined by the transformation from a multilayer graphite-like structure to a bulk wurtzite structure.”
Is the specific limit determined by the transition? Give the details for the transition and the formula required for the calculation on the value of the specific limit.
Line 157 “Due to the bandgap is very sensitive to the change in biaxial strain, We used a smaller step size of 0.5%.”-> “Because the bandgap is very sensitive to the change in biaxial strain, we used a smaller step size of 0.5%.”
Line 172 “Such as the CBM values of 5L ZnO and 6L ZnO lie above the reduction potential by 0.41 and 0.29 eV, respectively.”
It is strange that “Such as” is at the beginning of the sentence.
Line 187 “Figure.5 shows that the first absorption peak of 1L ZnO”-> “Figure 5 shows that the first absorption peak of 1L ZnO”
This reviewer thinks that the period “.” after “Figure” needs to be removed. Please check the guideline for the author on this journal.
Line 194 “but the absorption coefficient in the visible light region increases to some extent.”
They must show the specific value of the adsorption coefficient and compare it to the value of the unstrained ZnO. The rate of the increase is the key factor for the ability to tune by applying the strain in their work.
Comments for author File: Comments.pdf
Author Response
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