Development and Investigation of Photoactive WO3 Nanowire-Based Hybrid Membranes
, Nikita Sharma 3, Gábor Karacs 4, Lilla Nánai 5, István Kocserha 6, Klara Hernadi 5,* and Zoltán Németh 3,*
Round 1
Reviewer 1 Report
The problem of obtaining hybrid photoactive membranes have a current interest. And the research presented in the paper, I think, will be interesting to researchers. But unfortunately the idea is not fully developed. And I cannot recommend it for publication as presented. There are several critical points:
1. in the methodological part, it is necessary to present a schematic illustration of the preparation of a hybrid photoactive membrane;
2. one should study in more detail the optical properties of the membrane, how the amount of WO3, Fe2O3 and CuO effects the properties of the membrane, how the water contact angle changes, since in this case, I think, wettability will play a key role;
3. photocatalytic activity has not been practically studied, only one figure characterizing photocatalytic properties. I think it is necessary to provide data on the reuse of the membrane for several cycles. How long does photocatalytic activity last? The process kinetic parameters ets.;
4. should separate the process of removing the dye due to the process of adsorption and photocatalysis.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper describes the development and investigation of photoactive WO3 nanowires.
Since there is a significant discrepancy between the contents of the introduction and the actual experiments, it is necessary to reconcile these parts of the paper.
The authors explain in the 77th line of the paragraph that the advantage of WO3 photocatalyst is that it can use visible light while TiO2 can only use UV in this experiment. On the other hand, photocatalysis by WO3 is used ultraviolet lamps as an excitation light source. I think that the author(s) want to explain that visible light is also emitted from the UV lamp, but if that is the case, it is necessary to show the experimental results using a cutoff filter of 420 nm at a minimum.
The UV-Vis absorption spectra of WO3NW is also essential if visible light responsivity is to be discussed.
In this paper, Fe2O3 and CuO are loaded on WO3, but there is no explanation as to why these two types of metal oxides were selected for loading. The cited references that contributed to the selection of Fe2O3 and CuO should also be shown.
WO3 is described as nanowires by the author(s), but nanorods would be more appropriate because of their length. It seems too short to be called a wire, but what do the authors think?
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
1. In the first paragraph of the introduction the authors should also consider microplastics as contaminants of concern.
2. In the fourth paragraph of the introduction, although the cited oxides have a more efficient activity against visible light, the authors should incorporate the bandgap values based on the literature of these semiconductors to provide a more complete picture for the reader.
3. In the results section, the authors should clarify whether the images presented correspond to HRTEM or TEM micrographs, as the terms are used interchangeably throughout the manuscript. Transmission electron microscopy techniques should not be confused.
4. Authors are advised to incorporate ESD results in a single section.
5. In line 189 in the results section, the authors allude that they will describe the degree of crystallization of the as-prepared composites, however, no results are presented in this regard.
6. In the Materials and Methods section, in the description of synthesis methods, although the authors used a thermal treatment to prepare their composites, the correct name of the method is Hydrothermal and not Solvothermal, because all the synthesis was performed in aqueous medium. Even though both procedures are the same in essence, they only differ in the solvent used.
7. The vast majority of the results provide information on the morphology, structure and other surface features of the as-prepared WO3-based materials. However, this work is incomplete in its experimental approach, as the addressed photochemical assays are insufficient to discuss the photocatalytic activity of the synthesized composites. The authors should devote more efforts to investigate in depth the photochemical properties of their materials. A comprehensive study of the photochemical activity of new materials should at least contain impedance experiments (to investigate the semiconductors type, resistances of the catalytic system, reaction mechanisms, etc.), photocurrent assays against visible light, diffuse reflectance spectroscopy to determine the bandgap of the as-prepared semiconductors, etc.
The authors do not provide any information about the photocatalytic degradation mechanism. There is also a lack of information about the nature of the as-prepared heterostructures, the arrangement and modification of their band structure, the charge carriers generation when absorbing light, the shift of absorption bands as the semiconductors are modified, etc.
9. Finally, typo errors found in the manuscript should be corrected. For instance, "hydris" on line 82, percentage symbols on lines 253 and 255, using the correct symbol to denote crystallization water of a reagent (a central dot instead of a cross), and some others.
10. A thorough wording review is required
11. It is suggested to include in line 71, a recent reference https://doi.org/10.3389/fchem.2022.900622
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
The article is written in a good scientific language and is devoted to the synthesis and characterization of a material based on tungsten oxide for photocatalysis.
There are several comments on the manuscript:
1. In the text, the authors talk about the synthesis of tungsten oxide nanowires. But for such a statement, it is necessary to give the values ​​of the form factor of these particles, which can be easily calculated from TEM or SEM data.
2. To determine the phase composition of the composite material, it is necessary to use electron diffraction data, rather than elemental analysis (EDX), which was done by the authors. Did the authors manage to obtain electron diffraction data? can they be interpreted to determine the phase composition?
3. A more detailed description of the porous structure is recommended. It is necessary to bring adsorption and desorption isotherms, determine its type, and the type of hysteresis loop. That will allow us to talk about the size and shape of the existing pores. It also makes sense to present pore size distribution curves. The description of methods for calculating the porous structure in the methodological part should be expanded.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Q2 through Q4 can be judged to have been answered. However, Q1 is explained in the response letter, but there is no explanation in the text as to why only UV-A irradiation is used for WO3, which is responsive to visible light. This is not likely to convince the reader. Therefore, an explanation of the response letter should be inserted in section 2.4. Once this modification is completed, I will allow this paper to be published.
Author Response
Q1. (round 1) The authors explain in the 77th line of the paragraph that the advantage of WO3 photocatalyst is that it can use visible light while TiO2 can only use UV in this experiment. On the other hand, photocatalysis by WO3 is used ultraviolet lamps as an excitation light source. I think that the author(s) want to explain that visible light is also emitted from the UV lamp, but if that is the case, it is necessary to show the experimental results using a cutoff filter of 420 nm at a minimum.
We would also like to thank the reviewer who drew our attention to the importance of the above-mentioned question and its inclusion in the text. On this basis, we have inserted the following paragraph in section 2.4 (highlighted in blue in the text)
“In our experiments, high pressure tanning lamps (Cosmedico®) were used, which eliminates all the possibility of visible light emission. Consequently, any cut off filter was not required. In this part, it is mentioned only in general, that tungsten oxide can be a suitable material as photocatalyst that can harness visible light [49] and UV [50] as well, compared to titanium oxide which is effective only in UV light.”
Bai, et al. Surface decoration of WO3architectures with Fe2O3nanoparticles for visible-light-driven photocatalysis. CrystEngComm, 16 (2014) 3289-3295. https://doi.org/10.1039/C3CE42410C
M.S. Lima, et al. Synthesis, characterization and catalytic activity of Fe3O4@WO3/SBA-15 on photodegradation of the acid dichlorophenoxyacetic (2,4-D) under UV irradiation. J. Environ. Chem. Eng. 8(5) (2020) 104145. https://doi.org/10.1016/j.jece.2020.104145
Reviewer 3 Report
a 43% similarity of this art has been detected with another previously published by some of the authors (https://doi.org/10.3390/molecules27092951), however, I understand that it is due to the same project, maybe it is It is necessary to request an explanation to avoid any subsequent questioning for both the authors and the journal. This is very marked in the part of the results, perhaps it is appropriate to paraphrase the wording in another way.
Attached is the Turnitin report.
Comments for author File: Comments.pdf
Author Response
We thank the reviewer for drawing our attention to the need to carefully edit the manuscript to avoid self-plagiarism. On the other hand, as the reviewer wrote, this article is a brick of a larger project where we are working on the development and testing of different types of nanowire-based photoactive hybrid membrane structures, which may cause similarities between the articles. As requested by the reviewer, we have made several changes to the manuscript and these changes are highlighted in blue in the text.
Reviewer 4 Report
The authors made the necessary corrections in the text of the manuscript and provided full answers to the questions.
Although the reviewer does not agree with the answer about the need to present adsorption/desorption isotherms and other characteristics of the porous structure, on the whole the article after corrections looks more complete and informative. The manuscript may be published in the journal without further corrections.
Author Response
Once again, we would like to thank the reviewer for his valuable comments and suggestions for amendments. Furthermore, as shown below, we add some information on adsorption/desorption isotherms for our prepared membranes.
Figure a, b and c (see attached pdf) show the adsorption/desorption isotherms for WO3/cellulose, WO3@Fe2O3/cellulose and WO3@CuO/cellulose membranes, respectively. Based on the IPUAC classification, they are type 3, which means macropore size > 50 nm, and have H3 type hysteresis suggesting slit-shaped pores. Because the pore type is macro so BJH method not applicable to measure pore size distribution we plan to measure it using CT as we mentioned earlier.
Author Response File: Author Response.pdf
