Preparation of ZnO Thick Films Activated with UV-LED for Efficient H2S Gas Sensing
, Juan Carlos DÃaz-Guillen 2 and Laura Lorena DÃaz-Flores 1,*
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear Authors,
Thank you for such important and interesting research in the field of preparation of ZnO thick films. I agree in general with the entire structure of your manuscript, both in terms of updating your research and in terms of the evidence base. I will have just a few clarifying questions that I hope will help your future Readers understand the research in more detail:
1. Page 3. Section 2.1. Could you indicate not only the grinding/milling time, but also the rotation speed, cycle change, volume and other important technological factors?
2. Page 4. Fig. 1. As far as I understand, Silver metallization has uneven application/deposition? How could the torn edge of the electrodes affect the performance of the gas sensor? Does the geometry of the ZnO film itself matter in 2D (area when viewed from above)?
3. And one general, complex question. Was only one sample used for each of the 3 ZnO film thicknesses? Is there a difference in output characteristics between samples with the same ZnO film thickness?
Kind regards,
Reviewer
Author Response
Dear Reviewer,
We thank you for your review of the manuscript. We have made all the changes and improvements suggested, following your remarks as close as possible.
We are attaching a word file with the detailed list of our responses and changes as well as the text of the revised work, in which the corresponding changes are indicated.
Please see the attachment.
Sincerly yours.
Laura Lorena Díaz-Flores
Corresponding author
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript entitled "Preparation of ZnO thick films activated with UV-LED for effcient H2S gas sensing” discusses on the preparation of ZnO thick films and it’s effective usage towards H2S. The manuscript is well written, however it lack coherency between characterizations and gas sensing applications. Additionally, the following comments needs to be addressed before its further consideration for acceptance.
Abstract
1. How do the combinations of mechanochemical synthesis and screen printing deposition can be a greener route?
2. The second sentence of abstract needs to be revised as one can’t combine a single room temperature synthesis with different milling times.
3. 3rd sentences grammatically incorrect, where the meaning is so confusing.
Introduction
4. Why the abbreviation of ZnO-NE for zinc oxide nanostructures were used; specifically what does the NE stands for?
5. Introduction was written in a single paragraph, which limits the focus of specific aspects in the research.
6. Greener route means – use of less solvents, avoiding hazardous chemicals in the synthesis route, reducing harmful byproducts – you can google the rest. So, authors should justify why their synthesis is greener route?
7. Authors also must diversify their literature in this section by discussing other types of gas pollutant and active materials used in gas sensing applications. The following references might be useful for your references:
https://jmmm.material.chula.ac.th/index.php/jmmm/article/view/649
https://doi.org/10.1016/j.ijbiomac.2023.124079
Methods
8. Section 2.1 must be revised to write in better scientific style.
9. Section 2.2: “Between each layer a drying was carried out at 125 ° C” – how long is it?
10. Section 2.3: Scan change to scanning
11. Section 2.3: The statement “The measurement was conducted in an area of 10 x 10 µm, the composition of the powder was studied by Raman spectroscopy, using a WITEC Alpha 300 Raman Confocal whit a 400 nm excitation laser” – The size 10 x 10 µm refer to what? What’s the justification for such a narrow range.
Results & Discussion
12. Section 3.3: The description of morphology lacks in this section. Why the magnification of (g) is different from (a) and (d).
13. Section 3.5: 190 – 300 nm: UV region, while 300-900 nm falls under visible region. Please justify your statement.
14. What do authors mean by surface activation of ZnO via UV-LED?
15. Many of the characterizations (i.e.: raman, SEM, extensive XRD analysis) is not relatable to the gas sensing properties. Thus, these characterizations needs emphasize on how does it facilitate in the gas sensing application.
Comments on the Quality of English Languageplease refer above comments
Author Response
Dear Reviewer,
We thank you for your review of the manuscript. We have made all the changes and improvements suggested, following your remarks as close as possible.
We are attaching a word file with the detailed list of our responses and changes as well as the text of the revised work, in which the corresponding changes are indicated.
Please see the attachment.
Sincerly yours.
Laura Lorena Díaz-Flores
Corresponding author
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThis work focuses on the realization of a sensor based on nanostructured ZnO thick films on a glass substrate capable of detecting H2S gas using continuous UV-LED illumination at low temperature, as well as studying the sensitivity dependence on the H2S gas concentration. For this purpose, the mechanochemical method was used for ZnO synthesis, and the screen printing technique was used for thick film deposition, at room temperature. Morphological, structural, Raman, optical, and electrical analysis were performed. The electrical resistance of ZnO thick film upon exposure to H2S gas and other species was measured.
The manuscript needs to be revised and the following main points need to be carefully addressed before it can be considered for publication:
1. Due to the large literature in the field, the novelty of the paper should be clearly addressed in the manuscript.
2. The introduction needs to be improved. At lines 53-54, the authors mention several interesting applications of the ZnO structures, but fail to report representative examples in literature, such as at least one for ZnO-based UV-detectors.
3. At lines 54-57, for sake of completeness, among the other synthesis routes used in literature for preparing ZnO nanostructures already reported, it is indeed important to mention at least the carbo-thermal transport growth [DOI:10.1007/s00339-007-3946-4] and the electron beam evaporation [DOI10.1016/j.mssp.2017.08.015].
4. In the paragraph “2.3. ZnO thick films Characterization” the brand of the different reagents used is missed. Also, at line 127 the correct statement is: “by using a Jeol JEOL JSM-7600F Scanning Electron Microscope” (it is better to avoid calling a microscope as a “device”, the word “microscope” being much more specific and appropriate).
5. Moreover, still in the same paragraph, some measurement conditions are missing. About the SEM observations, the parameters used in the measurements (such as the acceleration voltage, the working distance used and so on) should be reported.
6. The authors should better clarify and underline inside the manuscript (it could be summarized in the conclusions as well) the advantages along with the disadvantages/limitations in using the synthesis technique employed for the realization of the ZnO nanostructures.
7. By using the synthesis methods described in the manuscript for synthetizing the nanostructures, how was the degree of control of the synthesis process? How the reproducibility of the samples was? And the stability in the time? The authors should mention and discuss in detail this aspect inside the manuscript (not only mentioning them in the conclusions).
8. Regarding the adhesion test, was it repeated after some time (months apart) to verify the durability of the adhesion force for a long time?
9. Fig. 9 should be reshaped to become easily readable; it could be cut into more than one figure.
10. In the conclusions, the authors state: “These results suggest that the combination of continuous UV-LED illumination and low temperature had a synergistic effect that helped to increase the sensitivity of the ZnO sensor”. However, it is clear that continuous UV-LED illumination and low temperature require energy consumption, so it seems that the proposed system is not so convenient. Authors should comment on this aspect within the manuscript to give the reader a clear and convincing explanation.
11. Finally, in the conclusions the value that the manuscript adds to the current literature on the subject must be underlined, together with the outline of some perspectives.
Author Response
Dear Reviewer,
We thank you for your review of the manuscript. We have made all the changes and improvements suggested, following your remarks as close as possible.
We are attaching a word file with the detailed list of our responses and changes as well as the text of the revised work, in which the corresponding changes are indicated.
Please see the attachment.
Sincerly yours.
Laura Lorena Díaz-Flores
Corresponding author
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript is well revised by considering all the comments. Thus, I recommend to accept the manuscript in the present form.
Reviewer 3 Report
Comments and Suggestions for AuthorsIn this revised version of the original manuscript, the authors have well addressed all the required points, and have satisfactorily improved the manuscript. Therefore, the revised version of the manuscript is now suitable for publication.
