Preparation and Photocatalytic CO Oxidation Performance Study of Au/Oxygen-Deficient (Anatase/B-Phase) TiO2 Heterojunction Microspheres
Tamer Zaki
Round 1
Reviewer 1 Report
Title
Please correct number in TiO2 to be TiO2
Authors did not refer to the several published works related to similar Au-TiO2 for the application of CO oxidation. They should do to clarify the novelty of their work.
Pages 4-5
- authors did not clarify the identity of the samples labeled (e & f) in the text and the capture of Figure 1 .
Page 5
It is better that authors identity and code the samples once in the experimental section and then using these codes in the discussion and in the captures of figures.
I suggest that authors should carry out surface area measurements and to qualitative detect experimentally the gold content of the prepared samples. I suppose the results of these requirements are important for explaining the data of the catalytic application.
No comment
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper presents the preparation and photocatalytic CO oxidation performance study of Au/Oxygen deficient (Anatase/ B-Phase) TiO2 hetero-junction microspheres. After peer review, I recommend this paper to publish in this journal. However, a major revision is needed before acceptance for publication. The comments and suggestions are appended below:
- Subscript of TiO2 in the title of the article.
- In the last paragraph of the introduction part, please give an advantage of a spray pyrolysis method compared with the dip coating, hydrothermal, and doctor-blading methods from other literatures. The references below should be cited.
- https://doi.org/10.1016/j.optmat.2023.113640
- https://doi.org/10.1016/j.mseb.2022.115793
- https://doi.org/10.1016/j.optmat.2023.113465
- Why was the prepared light-yellow transparent solution placed in a hot air-drying oven at 80oC for 390 min, not 100oC for 400 min?
- Fig. 1 should be enlarged and scale bar with its value should also be clear.
- Please enlarge the word and change color of alphabet for gold in Fig. 2(f) for clearer observation.
- For clearer, labels should be placed beside the XRD patterns.
- No label “a-f” on the XRD patterns, please recheck.
- Absorption spectra should be plotted with different symbols for clearer observation.
- Tauc’s plot analysis in each condition of the samples should be performed as Fig. 4(b)
- Also, PL spectra should be plotted with different symbols for clearer observation.
- In section 3.3, the detail mentioned to Fig. 6, not Fig. 4.6 (line 6 and 8), please recheck and revise.
- In section 4, the detail mentioned to Fig. 7, not Fig. 4.7 (line 2) and the band gap value of 3.13 eV for traditional B-phase TiO2 do not show in the mechanism diagram, please recheck, and make clarify.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
This Manuscript reported the characterization of the Au/TiO2 heterojunction photocatalyst and its performance in CO oxidation. The effect of gold loading amount and spray drying temperature on the prepared catalyst characteristics and performance were studied. It is recommended that authors specify the novelty of the work and improve the discussion.
- For better comparison it is recommended that the scales of the figure 1 b and c should be the same as figures 1 d, e and f.
- It is not clear that figure 1 e and f refers to which samples!
- How it is concluded from SEM images the gold agglomeration or larger gold particle formation as a result of the increasing the gold loading or drying temperature? It is recommended that specify the gold particles and their size on the SEM images.
- It is stated: "In samples d and e, the gold nanoparticles were more significantly aggregated in the sample prepared at 250℃ than those in the samples prepared at 200℃", but TEM images don't show this result.
- There was a typing mistake in the figure numbers in lines 351, 353 and 395.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
In the paper entitled "Preparation and Performance Study of Gold Nanoparticles/Oxygen Deficient (Anatase/ B-Phase) TiO2 Heterojunction Microspheres by Spray Pyrolysis and Study of Their Performance in Photocatalytic Carbon Monoxide Oxidation" Hong and co-workers described the preparation and photochemical evaluation of the heterogenous photocatalyst in the CO degradation. Although the obtained results are interesting, the manuscript should be revised before publication. Some issues need to be addressed:
1. To obtain Au nanoparticles, the reduction of the HAuCl4 solution must occur. Please describe how the AuNPs were formed (what was the mechanism) on the surface of the titania.
2. Instead of classic UV-Vis studies, please perform UV-Vis-DRS measurements as they are more adequate for the suspension of heterogenous photocatalysts as TiO2. In traditional UV-Vis studies, the turbidity of the sample may disturb the results obtained.
3. The PL spectrum revealed an interesting phenomenon in the range of approx. 650-750 nm, where the intensity of the material containing the lowest Au loading (red) is more significant than those with 1% of Au loading (light blue, pink). Please comment.
4. Please compare the obtained results of the photocatalytic studies with the literature data in table form. There is a need to indicate the efficiency of the material in comparison to other photocatalysts.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
In spite that the authors had corrected some minor comments, they did not follow the other suggestions such as: carrying out surface area measurements and qualitatively detecting experimentally the gold content of the prepared samples.
These evaluation tests are important for explaining the data of the catalytic application.
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
- The x-axis of Fig. 3, the unit should be “2-theta (degree)”.
- In Fig. 4, the paper shows the reflectance spectra, which is different from the author’s reply. If the author would like to show the reflectance spectra. Then, the sub-section of 3.2 Optical properties should be changed from “UV-Vis Absorption Spectra” to “UV-Visible Diffuse Reflectance Spectra (DRS)”. However, both absorption and reflectance spectra can also be performed as Fig. 4(a-b), respectively. Thus, the explanation should also be revised and rechecked.
- The x-axis of Fig. 5, change from “wavenumber” to “wavelength”.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
Dear Authors,
All my comments have been addressed. I have no further issues. The paper can be accepted in its present form.
Author Response
Dear Reviewer,
Thank you for the recognition!
