Synthesized TiO2 Mesoporous by Addition of Acetylacetone and Graphene for Dye Sensitized Solar Cells
Round 1
Reviewer 1 Report
Evaluation of the “Sol–gel synthesized TiO2 mesoporous by addition of acetylacetone and graphene for dye sensitized solar cells”
1.This work can be very interesting form experimental point of view however the presentation style should be radically improved; other comments are listed below
2.The English requires major revision as many sentences are very weak, starting with first sentence in which you indicate that “this study mixed”..rather you have to use “In this study were mixed” and many others;
3.You have indicated in abstract that the overall benefits is because of “which could be due to the appropriate TiO2 mesoporous size and raised” which seems not a very concluding indication…
4.In my opinion you have to reformulate the abstract in a better manner
5.Your introduction should be more critical and much more structured, besides this is very briefly presented
6.The scientific novelty and your contribution is not very well defined.
7.The first sentence in experimental details should be removed
8.Details of samples preparation for SEM, and TEM are missed
9.The quality of Figure 2 b is poor and not possible to distinguish “which could be due to the appropriate TiO2 mesoporous size and raised”
10.Line 143 please check this “The SEM images (Fig. 4b-d)” which is incorrect
11.In section 3.2 seems a discussion part rather then some results about mixing Acac and GP. At least first paragraph do not make sense now where is placed..
12.As pointed for abstract you said in results and discussion line 246 “This could be due to the appropriate TiO2 mesoporous size” which is not fit for a research paper. Rather I suggest indicating the values and their range…
13.Otherwise, despite of some interesting results their discussion against literature was not very successfully, please elaborate them in a better manner.
Author Response
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Reviewer 2 Report
1.L. 10: To say in the abstract that 1, 2 or 3 mL of acetylacetone is added is meaningless if we don't know how much TiO2 these volumes are added to.
2.By the way, nothing is said about the role of acetylacetone. One can suppose that it modifies the rheological properties of the mixture during grinding and/or spin-coating and can possibly modify the structure of the deposit, the size of the grains, the energy gap, etc., but there is certainly nothing left after calcination at 500°C.
3.Many analytical techniques have been used here (some of them somewhat superfluous, like Raman spectroscopy). On the other hand, it would have been very interesting to measure the particle size of the TiO2 after the (very long) grinding to see, in particular, if acetylacetone had an effect during this operation.
4.By the way, I do not understand what is said in lines 158-160.
5.The authors say that they produced their samples by sol-gel and spin-coating techniques but do not give any information in their "Experimental details".
While I can imagine that the preparation obtained after grinding might indeed lend itself well to spin-coating, I really don't see which step would involve the sol-gel technique.
6.The symbol recommended by IUPAC for the liter is "L" and not "l".
7.L 117: the phrase "ITO/electrolyte interplays and backward electron flow" is vague (especially the term "interplays") and probably means the same thing twice. The only function of the barrier layer is to prevent the reduction of triode ions at the anode (which would thus also act as a cathode to the electrolyte and thus short-circuit the cell).
8.L 117: "...results in both higher short-circuit voltage and ...", I guess ...
9.L. 146: "the chemical natural instincts (???) of the dopants".
10.The authors say that they have performed all the tests 4 times, which is a good point, because very often the authors do not give any information about this and one can suspect that in many cases the reproducibility is not checked. A good point, but unfortunately, the authors give here the average values ... without the standard deviations.
11.It is presumptuous to refer here to possible industrial applications, because one must realize that liquid electrolyte DSSCs have little future in industry. Moreover, these results are probably not transposable or extrapolable to cells using "solid" electrolytes and the interest here is therefore purely academic.
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Reviewer 3 Report
1. Abstract part – provide the full-term description of each elements/compounds used on the abstract portion
2. Line 14-15, much better to provide to insert first the method(s) used before presenting the x-ray diffraction patters which display the anatase type phase
3. Provide the basis why those compounds used as alternative in line 23-25.
4. Line 178, where is the 0 ml y axis?
5. Insert the basis of comparison in the results and discussion
6. Why all main headings are numbered with number “1” only?
Author Response
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Round 2
Reviewer 1 Report
Thank you to authors for improving the content.
I further suggest having a proof reading of english presentation and make the neccesary adjustemnents.
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Reviewer 2 Report
1.I thank the authors for taking the comments into account and making the changes.
However, I am sorry to say that my general feeling has not changed much.
2.It is still unclear by what mechanism acetylacetone (sometimes) produces some morphological changes within the deposit, at the energy gap, etc. It is not at all clear what is going on and there is no discussion of this crucial point which remains totally mysterious. It is an accumulation of observations without any attempt at explanation.
In fact, it could be that any organic molecule could produce similar (or perhaps very different ... and maybe better) effects. So why acetylacetone?
3.The same questions arise, of course, for graphene.
4.Another important point is that I still do not see at any point in the deposition process a step that is remotely similar to the sol-gel technique. This should start with a solution of a metal alkoxide (in this case Ti) which is first hydrolysed, then polymerised (by condensation) to form a cross-linked polymer which ends up trapping the solvent (gel). However, we are dealing here with pre-formed TiO2 crystals and it is therefore not a sol-gel process at all. The only deposition technique used here is spin coating. The title of this paper is therefore completely inappropriate.
Some more specific remarks:
5.In my question 3 : « On the other hand, it would have been very interesting to measure the particle size of the TiO2 after the (very long) grinding to see, in particular, if acetylacetone had an effect during this operation. », I was rather referring to real granulometric measurements (laser diffraction analysis) just after milling.
6. P. 4 : « Setting a dense blocking layer (compact layer) between the transparent conductive oxide and the TiO2 mesoporous to prevent the electron/hole recombination at the conducting oxide/electrolyte interface».
7.In my opinion, the purpose of the barrier layer is not at all to limit electron-hole recombinations (which is a purely physical phenomenon), but to inhibit the well-known chemical reaction of reduction of one triodide ions (I3-) into three iodide ions (3 I-) onto the ITO (or FTO) surface.
8.In electrochemistry, we say that we increase the resistance to charge (and/or mass) transfer.
9. P. 6: « Mixed non-metal elements with TiO2 changes the energy states in the band gap, affecting the sunlight absorbance region and the electron transport of the TiO2 [24]. »
10. Which element is it (knowing that it is absolutely clear that no acetylacetone nor any other common organic molecule remain after treatment at 500°C)?
11. I do have an idea, but it only half convinces me.
12. P. 6 : « The Eg for pure TiO2 is 3.223 eV. For mixing the Acac with TiO2, the Eg value decreased to 3.181 eV (for 1 mL Acac) and 3.076 eV (for 2 mL Acac), respectively. The Eg is 3.223 eV (pure TiO2) for the transition from the valence band to conduction band, which attribute to the charge transfer transition from O2– to Ti4+ . This value is in agreement with the TiO2 anatase particles. For the mixing the Acac with TiO2 sample, a lower Eg is 3.076 eV. However, the Eg increased to 3.374 eV with the increased Acac concentration. All specimens were very close to the studied Eg value of the anatase structure [23]. »
13. In this paragraph (whose English should be revised), some things are said twice and some things say exactly the opposite of what is said 3 lines above.
14. Now, if we look at figure 9, we can better understand what this paragraph is trying to say and the conclusion is that the band gap varies a priori randomly and that no conclusion can be drawn.
Kind regards.
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Reviewer 3 Report
Provide a further interpretation on Figures 13 to 15.
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