Synthesis of the Porous ZnO Nanosheets and TiO2/ZnO/FTO Composite Films by a Low-Temperature Hydrothermal Method and Their Applications in Photocatalysis and Electrochromism
Round 1
Reviewer 1 Report
The article entitled as Synthesis of the porous ZnO nanosheets and TiO2/ZnO/FTO composite 2 films by a low temperature water bath method and their applications in 3 photocatalysis and electrochromism. In this work, Xusong Liu, Gang Wang , Hui Zhi , Jing Dong , Jian Hao , Xiang Zhang , Danting Li, Baosheng Liu , Jing Wang prepared the porous zinc oxide (ZnO) nanosheets using simple low-temperature water bath method and heat. And used photocatalyst for degradation of methyl orange (MO), 20 methylene blue (MB) and Rhodamine B (RhB) were 97.5%, 99% and 96.8%, respectively. The overall rating of work is very good. However, there are some gap in this work. The following point must be considered before final acceptance.
1 As for as semiconductor photocatalyst are concerned, adsorption plays very critical role. No doubt, ZnO has adsorption properties. The authors must add a paragraph involving heterogeneous photocatalysis. For aqueous phase pollutant degradation adsorption is highly needed. The authors must discuss basics of heterogeneous photo catalytic process by discussing the latest work.
https://doi.org/10.1007/s10311-020-01066-x
https://doi.org/10.1016/j.matlet.2022.131716
- The authors must mention the advantages of photocatalysis over other treatment techniques. Plz discuss with reference to pioneer work in field.
https://doi.org/10.1016/j.jhazmat.2021.125324
- How the reusability photocatalyst/adsorbent can be assured? the magnetic adsorbents are of high importance. How will you separate non-magnetic photocatalyst Plz discuss their role as adsorbent separation during for water purification? How can we investigate catalytic activity over number of catalytic cycles’? Plz refer for some the papers for better expolantion
. doi: 10.1016/j.ijbiomac.2019.04.004.
https://doi.org/10.1016/j.jclepro.2020.124319
https://doi.org/10.1016/j.jcis.2020.07.047.
- The Figure 2 and Figure 4 must be improved. It is not clear
- The mechanism figure must be improved.
7 The conclusion must be re-written in a more conclusive way.
- GA is very crowded. The left-hand side scheme could be deleted.
Author Response
Please see the attachment
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript entitled “Synthesis of the porous ZnO nanosheets and TiO2/ZnO/FTO composite films by a low temperature water bath method and their applications in photocatalysis and electrochromism” has been submitted by the authors. Some issues to be addressed will improve the quality of the manuscript. Therefore, I recommend this work could be published after the major revision
- The English composition requires many improvements. The authors should proofread the manuscript carefully to minimize grammatical errors.
- In Fig. 1, the Inner font size is very small and unclear. Please make the text visible.
- In Fig. 2, X and Y axis titles missing
- The author should add an XPS analysis of TiO2/ZnO composite films.
- Enough references do not support the characterization and result, and discussion parts. It may be supported by the recent relevant references (before 2015). Scientific Reports 6, 20103 (2016); Coatings 2021, 11(12), 1464; Materials 2021, 14, 3299.
Comments for author File: 
Comments.pdf
Author Response
Please see the attachment
Author Response File: Author Response.docx
Reviewer 3 Report
In this work, ZnO nanosheets and TiO2/ZnO-based nanomposites were prepared by chemical method. The products were used for photocatalytic dye degradation, while their electrochromic properties were also studied. Several improvements need to be done before considering this work for publication. Please see comments below.
- Experimental part: Do you prepare two different solutions, one with Zn-nitrate, one with Na2CO3 and then you add the latter to the first one? This is not clear at the first three lines of the section 2.1. Please improve your writing. There it seems that you added both precursors at the same solution of 20 ml of water. Be more clear, please.
- A water bath is not the same as hydrothermal process! Other thing is a water bath, other thing is an autoclave. The latter is a sealed system, a closed system. Please make corrections in your text. Also, you mention water bath heating at 60 C for 12h but at the Figure 1 we see a closed system at 150 C and 12 h. You have messed up some information, it seems.
- Line 217: you write ‘the mass of zinc oxide’ but at the Table 1-1 we use that you use the composite material ZnO-TiO2-FTO. There is a confusion there, do you see it? You do also characterization such as XRD and others for ZnO ‘alone’ but in the catalysis you used the combined composite. Any comments? Actually, what is FTO? You should define abbreviations, you know.
More comments follow:
Line 26: You write ‘when the material was used as an electrode, it showed…’ . But in which context was it used as an electrode? We deposit a material onto an electrode for some reason, always. Which was the reason, the context in your case?
Line 29: Is your material ‘polymetallic’ or composed of ‘multiple metal oxides’ maybe? ZnO and TiO2 are metal oxides, not metals.
Line 38 and 40: You write the word ‘achieve’ two times. You can use synonyms, also. Also, the whole phrase has wrong syntax.
Page 2/13, line 54: You can remove the part ‘in our lives’.
Line 52: For shape-tuned ZnO nanostructures with gas sensing ability, see also a paper at: Journal of Nanoparticle Research, year 2015, Vol 17, article number 280. You can cite this paper.
Next paragraph, line 74: Better write ‘length’ and not ‘diameter’. Then at 4th line you write that you study the photocatalytic and electrochromic properties of these materials, but this you write it also at the 2nd line of the same paragraph! Please, avoid repetitions.
Why you write so many results at the Introduction? Remember, it is only an Introduction. You have to make the rest of your manuscript attractive for the reader. Not write already so many results. You also write things about the effect of particle size and the surface area, as well as other parameters, adsorption effect and so on! Look, I repeat: this section is not ‘results and discussion’, it is just an Introduction.
At the last paragraph of Introduction, already it seems that you pass at Conclusions and Perspectives. It seems a bit awkward that you write about the impact of your work there. It is just an Introduction, remember. Read some more papers, please, in order to see what is the common structure and content of an Introduction.
Centrifugation with water and ethanol: write centrifugation speed in rpm and centrifugation time in minutes.
The Figure 1 is not so visible. Please replace it with one of better quality.
Line 158: Better ‘rinsed’ instead of ‘washed’.
You do not write at all any ‘materials and methods’ section. We have to see the purities of your chemical reagents and where did you buy them from.
Line 163: You write that the size is ‘thick’. But techniques such as the SEM help us to say also numbers, right? Give mean size in numbers, in nanometers (or micrometers, depending on each case).
Start of section 3, Results: To which heat treatment you refer to, is it the calcination stage? Once again, be clear, please! Anyway, often the heat treatment causes aggregation and bigger size. In your case, somehow it caused smaller size. Is it because the sheets ‘broke’ somehow?
Caption of Figure 3: There is a mistake there: the graph ‘c)’ is the energy spectrum and the graph ‘d)’ is the XRD. Please correct it.
Line 218: A centrifuge tube with which volume capacity? 10 ml, 20 ml, 40 ml?
The figure 4 is not well visible, replace it with one of a better resolution-quality please. The same for the Figure 6. Replace it with a better one.
Figure 8 has bad quality. Replace it please.
References list: Ref 21 is the same with Ref 22: So delete the Reference 22 and re-arrange the numbering of references in both main text and list of references.
Author Response
Please see the attachment
Author Response File: Author Response.docx
Reviewer 4 Report
Manuscript ID: coatings-1678267
General comments:
In this manuscript entitled “Synthesis of the porous ZnO nanosheets and TiO2/ZnO/FTO composite films by a low temperature water bath method and their applications in photocatalysis and electrochromism ", the authors have reported synthesis of the porous zinc oxide (ZnO) nanosheets by a simple low-temperature water bath method and heat treatment for the first time. They found the excellent methyl orange (MO), methylene blue (MB) and Rhodamine B (RhB) degradation efficiencies by porous ZnO nanosheets. Authors also reported that when TiO2/ZnO/FTO composite was used as the electrode, shows large light modulation range (55% at 1000 nm) and excellent cycle stability (96.6% at 200 cycles). The work is adequate. The comments may be useful for the improvement of the manuscript. Minor revisions are needed to make the work acceptable.
- Comment:
Please start the abstract by a short introduction of the current problem(s) and the solution, based on the current study, in one or two lines
- Comment:
The introduction can be improved by providing a more critical discussion of recent related literature.
- Comment:
Kindly explain the novelty of the resent work in one or two lines in the introduction.
- Comment:
Kindly improve the quality of the SEM and TEM images.
- Comment:
Kindly improve the quality of all Figures. Figure quality is very poor.
- Comment:
Kindly provide the adsorption study of the prepared photocatalysts.
- Comment:
A suitable mechanism should be purposed to explain photocatalysts.
- Comment:
Are the synthesized photocatalysts are active in visible or sunlight.
Author Response
Please see the attachment
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
the revised work looks good.
Author Response
感谢审稿人的支持
Reviewer 3 Report
In the 'response to reviewer' I see that the authors answered 'point by point' only to some of my comments. Not to all the comments. Why is that? Please see comments below. I put them again here. Also, the quality of some Figures is still not good. Furthermore, the Introduction was not corrected sufficiently, as I suggested. I repeat, please see comments below and answer point-by-point:
In this work, ZnO nanosheets and TiO2/ZnO-based nanomposites were prepared by chemical method. The products were used for photocatalytic dye degradation, while their electrochromic properties were also studied. Several improvements need to be done before considering this work for publication. Please see comments below.
- Experimental part: Do you prepare two different solutions, one with Zn-nitrate, one with Na2CO3 and then you add the latter to the first one? This is not clear at the first three lines of the section 2.1. Please improve your writing. There it seems that you added both precursors at the same solution of 20 ml of water. Be more clear, please.
- A water bath is not the same as hydrothermal process! Other thing is a water bath, other thing is an autoclave. The latter is a sealed system, a closed system. Please make corrections in your text. Also, you mention water bath heating at 60 C for 12h but at the Figure 1 we see a closed system at 150 C and 12 h. You have messed up some information, it seems.
- Line 217: you write ‘the mass of zinc oxide’ but at the Table 1-1 we use that you use the composite material ZnO-TiO2-FTO. There is a confusion there, do you see it? You do also characterization such as XRD and others for ZnO ‘alone’ but in the catalysis you used the combined composite. Any comments? Actually, what is FTO? You should define abbreviations, you know.
Author Response
Please see the attachment
Author Response File: Author Response.docx
