A High-Performing Nanostructured Ir Doped-TiO₂ for Efficient Photocatalytic Degradation of Gaseous Toluene

Round 1

Reviewer 1 Report

This work reports three Ir-doped TiO₂ catalysts for photocatalytic degradation of gaseous toluene. They have shown that photocatalytic degradation efficiency could reach up 97.5%. Some basic characterizations were done. The following issues should be addressed before its publication.

1) As shown in the introduction, a series of M-doped TiO₂ photocatalyst (M=V, Cr, Fe, Co, Mn, Mo, Ni, Cu, Y, Ce and Zr) have been investigated for photocatalytic degradation of similar organics, why the authors choose to study Ir-TiO₂? The Ir is very expensive.

2) In section 2.2, the catalyst preparation was described in other previous work, does it mean that the catalysts have been reported for other applications?

3) In fig. 2, what is the use of activated carbon? The GC should be presented in the figure. Also, the model number of GC should be provided.

4) In table 1, 0,62% should be 0.62%. Please revise them.

5) How did the authors calculate the decomposing efficiency? The corresponding formula should be provided. “The toluene degradation reaction at optimum condition was repeated three times” Please provided the original GC file and data record, as well as the experimental records to illustrate the repeated experiments.

6) In table 3, only four other reported catalysts are not enough.

Author Response

Dear Prof. Dr. Maryam Tabrizian,

Thank you for your favorable response to our manuscript entitled: “A High-Performing Nanostructured Ir Doped-TiO₂ for Efficient Photocatalytic Degradation of Gaseous Toluene”. Manuscript number: materials-1554829.

We would like to express our gratitude for the Editor and Reviewer’s efforts to improve the quality of this manuscript. We are herewith sending the revised manuscript which has been corrected based on the suggestions from you and the reviewers, including extensive revision in English grammar as well as a reorganized structure based on previous content. We have labeled with blue words to show changes and/or additions to the previous manuscript.

We appreciate the expenditure of your time and effort in considering our manuscript and we look forward to hearing from you soon.

Sincerely yours,

Prof. Van Thi Thanh Ho

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript "A High-Performing Nanostructured Ir Doped-TiO2 for Efficient 2 Photocatalytic Degradation of Gaseous Toluene" in general is well written and organized. Nevertheless, some key points need to be reviewed as follows:

1) a)What is the toluene/distilled water ratio that is injected into the photoreactor? and b) what is the effect of the water on the photocatalyst?

2) Please insert the JCPDS card for the IrO₂ even when it wasn't detected on the XRD diffractogram.

3) Page 6, lines 14-17. a) The statement regarding the doping evidence based on the not detection of IrO₂ is not necessarily true, since the low concentration of Ir could not be enough to be detected.

b) In addition, discussion on peaks displacement is missed and it is very important to sustain the doping of TiO₂. 

c) The crystallite size could be determined for the different Ir concentration samples and discuss such sizes and doping relationship.

4) Please discuss why the peaks around 27 and 36 2Θ are reduced in their intensity as the nominal Ir concentration was increased.

5) Please provide a TEM image for the pure TiO₂ because it is not clear the mentioned rods of it. Spherical particles are easily observed but not rod morphology.

6) Please discuss the physisorption results based on the Ir concentration, for example, in terms of how the pore diameter or volume was modified. If the manufacturing method is mentioned then discuss it in detail regarding differences, advantages, and disadvantages.

7) a) In section 2.4 the use of the sunlight is mentioned but in the results section, it is not presented nor discussed. Please modify it.

b) In addition, XPS and PL analysis are also mentioned in the experimental section but they are not presented in the result section. Please modify it.

8) The conclusions could be improved by mentioning the doping effect and how it was achieved and corroborated.

 

Author Response

Dear Prof. Dr. Maryam Tabrizian,

Thank you for your favorable response to our manuscript entitled: “A High-Performing Nanostructured Ir Doped-TiO₂ for Efficient Photocatalytic Degradation of Gaseous Toluene”. Manuscript number: materials-1554829.

We would like to express our gratitude for the Editor and Reviewer’s efforts to improve the quality of this manuscript. We are herewith sending the revised manuscript which has been corrected based on the suggestions from you and the reviewers, including extensive revision in English grammar as well as a reorganized structure based on previous content. We have labeled with blue words to show changes and/or additions to the previous manuscript.

We appreciate the expenditure of your time and effort in considering our manuscript and we look forward to hearing from you soon.

Sincerely yours,

Prof. Van Thi Thanh Ho

Author Response File: Author Response.docx

Reviewer 3 Report

Title: A High-Performing Nanostructured Ir Doped-TiO2 for Efficient 2 Photocatalytic Degradation of Gaseous Toluene

Present manuscript discusses the synthesis and characterization of Ir doped TiO2 for photocatalytic degradation of Gaseous Toluene. The application of photocatalytic materials for abatement of environment had studied since last 5-6 decade, mainly focusing the removal of toxic pollutant from water. The degradation of gaseous pollutant has not been focused till today seriously. I feel that this is one of the important area of research and many more studies in this area should be published focusing enhancing the quality of the air by degradation of various air pollutants. So I would like to recommend the publication of the present manuscript after revision, authors are requested to include the following points in the revised manuscript for further consideration.

1. As per the figure 3, it is clear that the rutile phase in undoped-TiO2 higher as compared to the doped TiO2, author need to explain why?
2. Also in case of 1.5% Ir doped TiO2 the peak corresponds to Anatase is very strong, if authors have used same experimental conditions then how it is possible to get difference in the noticeable XRD peaks.
3. Authors are requested to provide the area under Anatase and rutile peak of the doped and undoped TiO2. Some reports explained that due to the doping of metal the transformation of anatase to rutile increases author can see the on doping of metal ion of TiO2 and change in the rutile peak given in Industrial & Engineering Chemistry Research, 2009, 45 (15), 5231-5238
4. In sample characterization it is mentioned that the sample analysis done by using XPS but not provided in the manuscript. Auhtor need to include XPS analysis of the undoped and doped catalysts. similarly, photoluinescence spetrum of all catalyst need to be provided.
5. On page 6, it is mentioned that “The nanorods are corresponding to the formation rutile phase, while the nanocubes are related to anatase phase.” Authors need to check and correct the sentence, as  do not find any nanorods in the image.
6. What is STT in table 1.
7. Figure 6 : authors are requested to provide the surface area of undoped and doped TiO2 only, no need to provide the surface area of other TiO2 samples, figure may be corrected accordingly. The surface area of the undoped TiO2 preapred by same method has not provided in the manuscript, and it is must to compare with the doped photocatalysts.
8. What was the position if Ir in the structure of TiO2 after doping? Is it substitutional or interstitial?
9. Why there is change in the surface area need to be explained in the manuscript by stating the position of Ir ion in the crystallite structure of the TiO2.
10. Is UV-Vis absorption spectra of doped TiO2 is compared with “anatase TiO2”? (page 8 line 16), I think it might be pristine or undoped TiO2, Author need to check and correct the same.
11. As with increase in the amount of Ir the reduction of bandgap taking place, why author have not doped Ir more that 1.5% to reduce the bandgap for further enhancement in the light absorption capacity? It is requested to include the answer in the revised manuscript
12. Page 8, line 11-13, please check the sentence, 1) is 0.5mol% is correct? 2) The photocatalytic activity first need to be compared with parallel synthesized pristine TiO2 and with other reported work.
13. Page 8, line 19-20 Please check and correct the sentence “In the present study, 1.5 mol% iridi-19 um-doped material showed the remarkably higher decomposing efficiency”
14. Authors need to provide the error bar in figure 8, 9, and 10
15. Auhtor need to triplicate all the experiment and same should be stated in manuscript.
16. Please replace “untreated” by “un-doped” or “Pristine TiO2” in figure 8,9, and 10
17. In conclusion it iststed that "Regarding optical property, the adsorption range of the 7 Ir-doped TiO2 photocatalyst was expanded to visible light." but the experiments were conducted in under UV lamp which is given in section 2.4.
18. Auhtor need to perform the experiment using UV and Visible tube and both the data should be compared.
19. Authors need to check complete manuscript for typos and grammatical mistakes.

Author Response

Dear Prof. Dr. Maryam Tabrizian,

Thank you for your favorable response to our manuscript entitled: “A High-Performing Nanostructured Ir Doped-TiO₂ for Efficient Photocatalytic Degradation of Gaseous Toluene”. Manuscript number: materials-1554829.

We would like to express our gratitude for the Editor and Reviewer’s efforts to improve the quality of this manuscript. We are herewith sending the revised manuscript which has been corrected based on the suggestions from you and the reviewers, including extensive revision in English grammar as well as a reorganized structure based on previous content. We have labeled with blue words to show changes and/or additions to the previous manuscript.

We appreciate the expenditure of your time and effort in considering our manuscript and we look forward to hearing from you soon.

Sincerely yours,

Prof. Van Thi Thanh Ho

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors have addressed my questions well.

Reviewer 2 Report

Dear authors,

 

Thank you for considering the reviewers' comments. It looks better and it was enhanced.

Reviewer 3 Report

Authors tries to improve the manuscript based on the reviewers comment by and large. I recommend the acceptance of this manuascript