Improvement of Photocatalytic Performance by Building Multiple Heterojunction Structures of Anatase–Rutile/BiOI Composite Fibers

Round 1

Reviewer 1 Report

The article describes the use of anatase-rutile/BiOI composite fibers for photocatalysis.

The theme is interesting, although some concerns must be addressed:

-          Please improve the state-of-the-art, at this moment it looks like a technical report, not like a scientific one.

-          Try to highlight a little more the aim and novelty of the study.  

-          Please provide full information about used reagents and instruments (company, city, country).

-          Please modify “ml” with “mL” throughout the manuscript.

-          All figures must be included after their first mention in the text.

-          Please improve the size and resolution of figure 4.

-          The same comment for figures 5, 7, and 10.

-          Figure 7: The abscissa axis must be reversed: from 4000 cm^-1 to 500 cm^-1.

-          Figure 7: It seems that, for the red sample, a shoulder (or a peak) appeared at about 3000 cm^-1, and it was not assigned. What about it?

-          Figure 10: in my opinion, the green color must be replaced with a more appropriate color.

-          Table 2: please use the same number of decimals.

-   Please specify whether or not the prepared composite was more efficient compared with other studies.

 

-          It is mandatory that the English language is revised by a native English speaker.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

 

In this paper the authors conduct research about photodegradation of methyl orange by using TiO2/BiO2 composite. The research is quite interesting, however, there are some parts that have to be modified. The comments and suggestions are listed below.

1.       In the Introduction section, please add some literatures about the previous report of TiO2/BiOI composite photocatalyst and add your uniqueness about Fiber morphology. It will be more interesting for the reader.

2.       It is very interesting when the BiOI was homogeneously attached on the TiO2 fiber for T/B-3 sample. What is the main factor of the homogeneous attachment of BiOI on TiO2 surface?

3.       In the XPS Analysis the author wrote “. After recombination, the peak of Ti 2P1/2 shifts to the direction of higher binding energy by at most 1.3 eV, which again proves the formation of heterojunction structure”. Can you explain the detail the shifting phenomena with the heterojunction formation?]

4.       In Figure 9(a), please add symbol for identify the degradation ability.

5.       In the mechanism section, the band structure was made between TiO2 and BiOI only. However, in the title the authors mentioned about Anatase and Rutile formation. I think it is better to revise the mechanism by adding Anatase and Rutile band structure, otherwise the title has to be revised.

 

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The authors presented a BiOI/TiO2 composite photocatalyst for photodegradation application. The performed extensive characterizations, including showing the significant enhancement in light absorption with BiOI leading to enhancement in the degradation rate of the composite. The manuscript can be published after the authors address the following:

1. In order to arrive at the band alignment and band bending in Figures 11a and 11b, it is important to know the fermi levels of the semiconductors. However, no fermi levels were calculated or measured. Can the authors comment on this? 

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

The manuscript "Improvement of photocatalytic performance by building multi- 2 ple heterojunction structures of anatase-rutile/BiOI composite fibers" deals with some interesting aspects of highly functional hybrid photocatalyst structures. In this work, TiO2 fibres have been electrospun and decorated with BiOI. Modification of bandgap structure is investigated and correlated to the photo-related properties. The authors have very nicely represented the work with interesting data. The microstructure analysis results are very interesting for the study. I strongly recommend this manuscript for publication. The manuscript, however, requires some revisions before being considered for publication.

1.     The introduction on similar work is very limited and is only focused on the subject. I strongly recommend authors give a broader overview of similar works on the electrospinning of oxide materials and application of fiber materials in photocatalysis. I strongly suggest authors consult following manuscripts in their revision:

-        Zhang, L., Hu, Z., Huang, J., Chen, Z., Li, X., Feng, Z., Luo, R. (2022). Experimental and DFT studies of flower-like Ni-doped Mo2C on carbon fiber paper: A highly efficient and robust HER electrocatalyst modulated by Ni(NO3)2 concentration. Journal of Advanced Ceramics, 11(8), 1294-1306. doi: 10.1007/s40145-022-0610-6

-        Zhang, L., Huang, J., Hu, Z., Li, X., Ding, T., Hou, X., Luo, R. (2022). Ni(NO3)(2)-induced high electrocatalytic hydrogen evolution performance of self-supported fold-like WC coating on carbon fiber paper prepared through molten salt method. Electrochimica Acta, 422, 140553. doi: https://doi.org/10.1016/j.electacta.2022.140553

-        T. Salehi, A. Taherizadeh, A. Bahrami, A. Allafchian, V. Ghafarinia, Towards a Highly Functional Hybrid ZnO Nanofiber‐rGO Gas Sensor, Advanced Engineering Materials, 22 (8) 2020, 2000005.

2.     I think the discussion on the implications of this heterostructure on the bandgap of synthesized composite can still be improved. The following article might be useful:

-        Facile Synthesis of Ag Nanowire/TiO2 and Ag Nanowire/TiO2/GO Nanocomposites for Photocatalytic Degradation of Rhodamine B, Materials 14 (4), 763, 2021

3.     Please provide more specific details in the conclusions. The current conclusion is rather generic. I suggest you re-write conclusions in bullet-point.

4.     A revision in English is recommended, though overall English is fine.  

5.     Pease introduce BiOI in the beginning of the paper.

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 5 Report

 

The research article ‘Improvement of photocatalytic performance by building multiple heterojunction structures of anatase-rutile/BiOI composite fibers’

In this research, some titanium and bismuth composite was synthesized and tested as photocatalysts for Methylene Orange decomposition under visible light. Visible light induced photo decomposition of organic dyes is a novel and interesting topic. However, the Authors still have room to improve this manuscript according to some remarks:

 

·       Does BiOI stand for Bismuth oxyiodide? It must be clarified in the manuscript.

·       Please explain how “homemade electrospinning equipment” is constructed. There are many different types of them. Also, all parameters such as distances, the density of the spinning solution (as it is changing over time and leads to different types of spinning structures), length and width of the needle, pumping speed, substrate type and dimensions, etc. should be added to the manuscript. Detail schemes and pictures of used equipment also must be added to the manuscript. Without it, the rest of the paper loses its impact as experiments aren‘t reproducible.

·       Parameters for light enhanced decomposition are also not clear. What was the distance between the sample and the lamp? What was the illumination intensity? These parameters are crucial as they highly affect the decomposition of MO. Also, it is important to know these parameters to be able to compare results with other published research.

·       The synthesis of TiO2/ BiOI is not clear. Was it an electrospun structure or TiO₂ was electrospun and then hydrothermal formation used? This must be clarified in the manuscript.

·       Fig 1 shows samples before annealing. SEM images of samples after annealing must be added to the manuscript. How did the Authors avoid agglomeration of sample B3 during annealing?

·       Table 1. How could Authors explain TiO2 composition of 21,9% - Ti and 64,41% - O? Where is the rest of 13,69%? For T/B samples situation is the same….

·       As it is stated in the title, that photocatalytic performance was improved results should be compared with other researchers results. A table for that should be made.

·       Conclusions should be rewritten and more specific. Also, it should be explained how much the photocatalytic performance was improved in comparison to other studies.

In this article, the Authors did a great job to analyse the photodecomposition of Methyl Orange, but there are many unclear sections in this work. Also, the reproducibility of this research is doubtful. The Authors should add important details on how experiments were conducted.

Author Response

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Round 2

Reviewer 1 Report

The manuscript can be accepted in its present form.

Reviewer 4 Report

Authors have properly addressed all comments. I believe this paper can be published as is. Thanks

Reviewer 5 Report

The authors significantly improve the manuscript. Thank you for the answers.