Electrochromic and Electrochemical Properties of Co3O4 Nanosheets Prepared by Hydrothermal Method
Round 1
Reviewer 1 Report
REPORT on coatings-1957051, “Electrochromic and Electrochemical Properties of Co3O4 Nanosheets Prepared by Hydrothermal Method”, Ying Duan, Gang Wang, LiCai Fan, Jing Wang, Xiang Zhang , MingLi Yang and JinHe Yuan.
The authors report the design of Co3O4 nanomaterials by a simple hydrothermal method. They concluded that the synthetic material reaches high specific capacitance, has good cycling stability, and shows excellent electrochemical performance when used as positive electrode. The analysis of the electrochromic properties revealed high transmission contrast and short response time.
The present work is an important contribution to the development of supercapacitor electrode materials, since it describes the preparation of Co3O4 nanosheets with good capacitive and electrochromic properties. Consequently, the results are interesting to the community of the journal Coatings. The clarity and length of the manuscript are appropriate, and it is adequately referenced. The quality of the English employed in the text is good. The number of figures is adequate, but their quality must be improved.
In my opinion, it is acceptable for publication in this journal and minor corrections are needed with no further revision:
i) In page 2, line 50: the author of Ref. [9] in the text (H. Wang) does not match with any of the authors of Ref. [9] in the list of references (Yan, W.; Kim, J.Y.; Xing, W.; Donavan, K.C.; Ayvazian, T.; Penner, R.M.). Please check this reference.
ii) The expanded form of the following abbreviations must be provided in their first appearance in the text:
- CNTs in page 2, line 73 (carbon nanotubes).
- ASC in page 3, line 106 (asymmetric supercapacitor).
- SEAD in page 4, line 140 (selected area electron diffraction).
iii) The quality of the figures is quite poor. Figs, 2, 3, 5, 6, 7 and 8 are very pixelated and in some of the plots there seems to be some shadows around the lines. The authors must make sure that the figures have the appropriate resolution.
iv) Figure 5 must be checked and corrected. For example:
- The caption for Fig. 5.b) reads “Charge/discharge curves at current densities of 1, 2, 3, 5, 8, and 10 A/g”, but these current densities does not match with the ones included in the figure (1, 3, 5, 8, 10 and 15 A/g).
- The caption for Fig. 5.c) reads “The inset is the cycling property with the density of 3 A/g”, but the inset is missing in c).
- The inset for Fig. 5.d) reads “Cycling performance under the condition of different current densities”, but only 5 A/g is included in d).
v) Figure 7 must be checked and corrected. The caption for Fig. 7.b) reads “Cyclic voltammetry curve of Co3O4//CNTs asymmetric device when the voltage window changes from 0.8-1.6 V at a sweep speed of 20 mV/s” but the scanning speed showed in Fig b) is 20 mV/s.
Author Response
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Reviewer 2 Report
Comments to the authors
The manuscript entitled “Electrochromic and Electrochemical Properties of Co3O4 Nanosheets Prepared by Hydrothermal Method” has been submitted by the author. However, there are still major concerns that need to be addressed before publication. Therefore, I recommend this work could be published after the major revision.
- As far as novelty of the work reported in the manuscript, it is neither reflecting from the choice of novel materials selected nor from the method of preparation. Author should rewrite the introduction part with stat of art.
- Lots of same type of materials already reported in the literature. Author should explain the novelty of work.
- Separate paragraph has to be written on materials performance and properties of Co3O4.
- Author should write the experimental procedure in continuously not in bullet point or numbering.
- XPS should be provided.
- What is the concentration of KOH in the saturated calomel electrode reference electrode?
- The EIS data needs to be better explained. For example, add an equivalent circuit. References also need to be cited.
- Also, looking to the presentation of the manuscript with respect to English language, it is not properly written and presented.
Author Response
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Reviewer 3 Report
The article "Electrochromic and Electrochemical Properties of Co3O4 Nanosheets Prepared by Hydrothermal Method" details the electrochromic and electrochemical studies on hydrothermally prepared porous Co3O4 nanostructures. The electrochemical performance and stability of the electrodes and an asymmetric supercapacitor based on this material is described. The material is reported to show appreciable specific capacitance and energy/power density values. I recommend a major revision due to the following reasons:
1) The English language is poor
2) The article is carelessly written. There are many wrong captions, contradicting data and type errors.
3) The introduction needs to be improved. As the article focusses on two major applications of the material, the introduction needs to address both and the rationale behind selecting this material is to be emphasised.
4) In a few references cited in the introduction, a few gives only the specific capacitance, a few gives cycling stability and so on. This should be consistent and should tell about the importance of the present work.
5) There is only one reference discussed on the electrochromic properties of this material. No other materials with similar properties are compared in the introduction.
6) The novelty of the study is not clear.
7) The authors use both specific capacitance and specific capacity for Cs in the manuscript. It should be consistent throughout.
8) The abbreviations of many terms are not expanded anywhere in the manuscript (eg. PEO-PPO-PEO and ASC). It should be expanded at the first mention.
9) Line 84 needs to be rephrased.
10) The SEM mapping given in Fig 1 is not clear. Clear images are to be provided.
11) Line 138 --- Use symbol instead of um for micrometers
12) Planes corresponding to the rings in the SAED pattern is to be labelled
13) No scale in figure 2b (HRTEM)
14) Fig. 4, Wrong caption. Carelessness
15) In figure 4, the images of coloured and bleached images seem to be interchanged.
16) 75% shown in Fig. 4 is misleading as it is labelled at 100% transmission region.
17) It can be seen that the coloured and bleached samples are different from the images in figure 4a. Provide the same sample.
18) The experimental details of the electrochromic property measurements are not given in detail.
19) In fig 4a, why is the transmittance more than 100% above 600nm?
20) Seconds to be abbreviated as small letter 's' (line 180, figure 4b)
21) Give the mass loading of the samples used for the 3-electrode measurements and device structure.
22) The data in Fig.5c and 5d are contradicting. It is given that the sp. capacitance is 1400 F/g @ 5A/g in Fig 5c whereas it is 1350 F/g @ 5A/g in fig. 5d (It is 1400F/g only at 8A/g).
23) In fig. 5e, x-axis should be 0 to 60 (Both the axes should have equal values)
24) In fig 5d, stability is reported at 5000 cycles whereas in fig 5e impedance is compared at 10000 cycles. Why?
25) Borders, legend, titles, tick marks etc. in the figures are not consistent throughout the manuscript. It should be uniform and legible.
26) Reason for the high electrochemical performance and cycling stability are not properly addressed. Compare with other articles published on the same material and explain.
27) No details on the electrode and device preparation are given, including details of the substrate/current collectors, whether any conducting material is used with the sample (if yes, ratio), etc.
28) Line 264, It is about the electrodes and not the devices. The statement has to be corrected (See figure 7a).
29) Fig. 7a, b,c.....y-axis labels are wrong. It is Current density.
30) Fig. 7a is wrong and contradicting. The labels of CNT and Co3O4 electrodes might have been interchanged. But the voltammograms of Co3O4 in fig 5a @ 20mV/s and Fig. 7a @ 20mV/s are different.
31) Fig. 8 caption is wrong.
Keeping all these comments in mind, the article may be thoroughly modified and resubmitted.
Author Response
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Round 2
Reviewer 2 Report
Authors solved most of the comments. Now the paper should be accepted
Author Response
Thanks for the reviewer's support
Reviewer 3 Report
The authors have not made revisions in any of the major issues I have pointed out. eg. The title of fig.4, image captions in figure 4a, English grammar and sentence formation, uniformity of graphs, SAED not labelled, and many more.
1) What is circled in the TEM image?
2) Please see the images and compare with the captions provided:
It seems to be wrong again.
3) For graphing, software like Origin or any scientific tool may be used.
4) In fig. 7a, a performance at 6mV/s is given instead of providing data at any scan rate given in fig. 5a (eg. 5mV/s). This rules out the possibility of any comparison. Hence, the authors have to provide the CV at 5mV/s.
5) Why is the data reported in specific capacitance instead of capacity?
Also, most of the answers to the reviewer's questions seem unprofessional.
Author Response
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Round 3
Reviewer 3 Report
The revised article "Electrochromic and Electrochemical Properties of Co3O4 Nanosheets Prepared by Hydrothermal Method" has many more serious flaws in its presentation and content. The authors need to gain an in-depth knowledge in the field before pursuing this work. Based on the following comments, I recommend a rejection.
1) The authors have reported the 3 electrode studies in 0.1 M LiClO4 and reported the device characterisation in 2 M KOH.
2) The corrections made by the authors have made the manuscript even worse
3) The caption of figure 4 is still wrong. This has been suggested right from the first revision.
4) The clarity and quality of the figures are still poor.
5) Carelessness from the authors part is evident from legend of figure 7a. what is Co3O?
6) See page 9, line 248-249. The article is carelessly prepared even in the third revision stage.
7) The authors have given the equations for reactions involving KOH and have reported that they have used LiClO4.
8) Most importantly, the comment on figure 7a and 5a in the previous revision was not answered correctly. The legend in figure 7a has just been renamed to 5mV/s which seem to be cooked up (Refer the previous versions for details).
6) The 3-electrode study was carried out in 0.1M LiClO4 whereas the asymmetric device studies were executed in 2M KOH (2M KOH was previously 3M !!!) which itself prove that the whole study is wrong and misleading.
7) There are still many issues in the manuscript including poor English language.
8) Page 10, lines 282-283. What does it mean?
Author Response
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