Development and Application of a Nano-Gas Sensor for Monitoring and Preservation of Ancient Books in the Library
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
I have carefully reviewed your manuscript entitled "Development of a TiO2 NTs/CNTs Nano Gas Sensor for Monitoring and Preservation of Ancient Books". While I commend the work, I would like to offer constructive feedback to improve the manuscript's scientific rigor and clarity.
1. In the preparation section, the authors do not specify the ratio of TiO2 nanoparticles to carbon nanotubes used in the synthesis. This information is crucial for reproducibility and validation of the results.
2. If EDS reports are added together with SEM images, they will support the claims about the composition.
3. The durability and robustness of the TiO2 NTs/CNTs nano gas sensor are crucial factors, particularly in the preservation of ancient books. Have you examined its long-term performance, taking into account environmental factors such as humidity, temperature fluctuations, and light exposure?
I believe these corrections and additions will significantly enhance the manuscript's contribution to nano gas sensors and their application in cultural heritage preservation. I look forward to the authors' response and the revised version of the article.
Author Response
Dear Prof., Reviewer
I am very grateful for your review of our revised manuscript (Coatings-2950704). I have revised the paper according to the helpful comments, as follows:
Reviewer's Comments
- The content of the article seems interesting. In it, in addition to describing the technology for obtaining high-quality NTs/MoS2samples, the synergistic effect of MoS2 sheets on the sensitivity of these sensors with respect to the NO2 content on the surface was studied and it was demonstrated that the addition of MoS2 sheets increases the sensitivity of this NO2 sensor by 8 times. At the same time, it is not clear why the authors already in the title of the work insist that these sensors are used as monitoring protection sensor for paper books, although using of the proposed sensors is much broader-monitoring the quality of air pollution, etc.
As the reviewer mentioned, with the advancement of human civilization, an increasing recognition has emerged regarding the paramount importance of paper books in libraries and museums. Our experimental results demonstrate that compared to pure TiO2 NTs, TiO2 NTs/MoS2 composites exhibit larger specific surface area along with higher sensitivity and faster response time towards various concentrations of NO2 gas. Our goal is to apply the nanomaterials of TiO2 NTs/MoS2 to develop a portable device based on book protection in the near future. The revision has been made in the abstract.
- I would also like to understand what the response of this system will be to other harmful gases, for example, CO, NH3, etc., since the sensor must unambiguously determine which gas affects to the conductivity of the sensor. To do this, it is desirable to check the sensitivity of the proposed system with respect to these gases.
As pointed out by the reviewer, we have added the sensitivity of the proposed system with respect to CO, NH3 and H2S at 260oC. The revisions has been added on Fig. 6 and P. 5, L. 180-184. Fig. 6 shows the responses to several harmful gases at the operating temperature of 260oC. The gas response to 100 ppm NO2 vapor is 3.3, which is significantly higher than all the other gases under the same concentration. The above results indicate that the selectivity of the sensor based on TiO2 NTs/MoS2 nanocomposites is very high and the sensor shows high anti-interference ability.
I have made a thorough correction of the misspelling and grammatical mistakes of the manuscript as highlighted in the manuscript.
Your favorable consideration would be greatly appreciated.
Sincerely yours,
Wang-Jia
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors
Reviewer:
The article presents interesting studies. The search for nanostructured materials for NO2 gas sensors is an urgent and promising task. To date, many different metal oxide semiconductor gas sensors have been proposed, which, due to their high sensitivity and fast response, are widely used for the determination of NO2, which include metal oxides. The proposed solution to this problem by the authors is original in terms of the synthesis of titanium dioxide together with carbon nanotubes. However, the work needs to be refined.
Кemarks:
1. The authors proposed the use of a NO2 gas sensor for monitoring the air composition of a library with ancient books. The question arises why exactly this application. There is no information on how air monitoring is carried out in libraries today and what the main problem is.
2. The work should include a real picture of the manufactured sensor for a better understanding of its shape, structure and current supply.
3. The technology of synthesis of nanocomposite material is sufficiently well described in the work, however, no information is given about the devices used to measure the main characteristics. It would be useful to provide their name and manufacturer, which would allow us to assess the reliability of the data obtained.
4. The results are presented in fig. 2 need a more detailed description. From the SEM photos, it is not clear at what magnification the images and other measurement parameters will be taken.
5. Research by X-ray diffractometry also requires detailing the wavelength at which the measurements were made and the crystal used to monochromatize the corresponding radiation.
6. Figure 3 needs to be analyzed more carefully. The analysis given by the authors in the article is not obvious from the presented X-ray diffraction spectra. Better argumentation and data presentation is needed.
7. Fig. 4,5,6,7,8 is difficult to evaluate as it is not indicated by which device the corresponding dependencies were registered. On RS. 5, 6, 7 there is a bifurcation of the main maximum, which may be related to this.
8. In the fourth chapter, considerations are given about the sensitivity mechanism of the synthesized nanocomposite, which is not clearly confirmed by the above measurement results.
9. The conclusions include the following statement " The hydrothermal synthesis of TiO2 NTs and CNTs composite narrows the band gap of TiO2, facilitating thermal excitation-induced migration of more carriers to the conduction band and enhancing their participa-tion in gas-sensitive reactions." which there is no confirmation in the text of the article.
Author Response
Dear Prof., Reviewer
I am very grateful for your review of our revised manuscript (Coatings-2950704). I have revised the paper according to the helpful comments, as follows:
Reviewer's Comments
This paper presents the synthesis and characterization of TiO2 nanotubes (NTs) and TiO2 NTs/MoS2 composites for gas sensing applications, demonstrating improved sensitivity to NO2 gas through enhanced surface adsorption and electron mobility, thus offering potential for real-time monitoring and mitigation of book aging in libraries. The feedback provided below offers suggestions to enhance the quality of the manuscript:
- You should add the significant findings, and the conclusions reached to your abstract. You should use quantitative value instead of qualitative adjectives.
I have revised the abstract and added the quantitative value of sensors based on TiO2 NTs/MoS2 composites. It is observed that flaky MoS2 is attached to the surface of TiO2 nanotubes, forming aggregated structures resembling flower balls.The TiO2 NTs/MoS2 nanocomposites exhibit a rapid response with a 5 s response time and an 80 s recovery time towards 367 ppm NO2 at 260oC. The gas response to 100 ppm NO2 vapor is 3.3, which is significantly higher than all the other gases under the same concentration. This revision has been added on P. 1, L. 14-18.
2- In the introduction, clearly identify the gap in the literature and explain how your research fills this gap.
As pointed out by the reviewer, I have revised the introduction and 6 relevant references have been added. It is noteworthy that the modification of TiO2 with 2D nanomaterials becomes an effective route to improve the inherent properties of TiO2 toward gas detection[8, 9]. The improved photodegradation activity and gas-sensing performance of MoS2/TiO2-NAs heterojunction nanohybrids were reported upon UV-Visible light irradiation[10]. The sensing mechanism of the Pd-TiO2/MoS2 sensor was attributed to the synergistic effect of the ternary nanostructures, combining the modulation of potential barrier with electron transfer[11]. Low dimensional MoS2/TiO2 composite was synthesized using hydrothermal method and the response and recovery times are as higher as 52 s and 155 s[12]. The novel features of MoS2/TiO2 heterojunction not only take the advantages of TiO2 nanotubes that fast electron transportation through vertical tube walls and high effective surface area facilitating more number of adsorption sites, but also can potentially present localized highly reactive areas by MoS2 modification and thus achieve unexpected characteristics for sensing applications[13]. However, to the best of our knowledge, only a few study has been published on the MoS2/TiO2 heterojunction on gas/vapor sensing performance. This revision has been added on P. 2, L. 52-67.
- When discussing metal oxide semiconductor gas-sensitive sensors and their characteristics, it would be helpful to provide a bit more context or examples of existing sensors used for similar purposes.
I have provided some examples of existing sensors based on MoS2/TiO2. The improved photodegradation activity and gas-sensing performance of MoS2/TiO2-NAs heterojunction nanohybrids were reported upon UV-Visible light irradiation[10]. The sensing mechanism of the Pd-TiO2/MoS2 sensor was attributed to the synergistic effect of the ternary nanostructures, combining the modulation of potential barrier with electron transfer[11]. Low dimensional MoS2/TiO2 composite was synthesized using hydrothermal method and the response and recovery times are as higher as 52 s and 155 s[12]. This revision has been added on P. 2, L. 54-60.
4- What was the rationale for using anhydrous ethanol as the solvent for dissolving the composite powder?
Many particulate substances can dissolve or partially dissolve in anhydrous ethanol, forming stable solutions. This dissolution action disperses the particulate substances in ethanol, preventing them from precipitating or aggregating. In addition, the surface activity of ethanol molecules at the interface of water and particulate substances enables ethanol to effectively disperse the particulate substances and maintain their dispersed state. This revision has been added on P. 2, L. 90-92.
5- Merge figures 2, 3 and 4. Also figures 7, 8 and 9.
I have merged the figures as pointed out by the reviewer.
- How was the decrease in sodium molybdate concentration correlated with the weakening of the characteristic peaks of MoS2in the XRD analysis?
By the assistance of MoS2, oxygen molecules can be more easily adsorbed on the surface of TiO2 nanotubes. A decrease in the concentration of sodium molybdate will result in a decrease in the MoS2 phase generated in the reaction, and therefore, the corresponding XRD characteristics will be weakened as can be seen from Fig. 2. This revision has been added on P. 4, L. 145-148.
7- Discuss any potential factors influencing the crystallization quality and phase purity of TiO2 NTs, particularly the oxidation time. Are there any implications of varying oxidation times on the gas sensing performance or structural properties of the TiO2 NTs?
The TiO2 nanotubes oxidized for 4 hours with superior crystallization quality for the TiO2 indicates a significant enhancement of the effective oxide surface area that may facilitate adsorption of target molecules, which is beneficial for the gas sensing properties of the TiO2 NTs. This revision has been added on P. 4, L. 160-163.
- Could you elaborate on the role of hydrated citric acid in promoting particle agglomeration and the implications of these aggregated structures on gas sensing performance?
The hydrated citric acid has the effect of promoting chemical reactions and particle agglomeration, leading to the rapid formation of TiO2/MoS2 nanocomposites. By the assistance of MoS2, oxygen molecules can be more easily adsorbed on the surface of TiO2 nanotubes. This process increases both the quantity of adsorbed oxygen and the molecule-ion conversion rate resulting in the greater and faster degree of electron depletion from the TiO2 which would lead to the decreasing of response time for TiO2 NTs/MoS2 nanocomposites. This revision has been added on P. 5, L. 174-180.
9- Replace 1, 2 and 3 in figure 5 to a, b and c.
I have replace 1, 2 and 3 by a, b and c in figure.
10- Add scale bar to figure 6.
I have added the scale bar in figure 6.
- Are there any implications of differences in surface morphology and clarity between TiO2NTs oxidized for 3 hours and 4 hours on the gas sensing performance or surface reactivity of the TiO2 NTs?
One can also see from SEM images that TiO2 NTs surface were substantially coarsened after attachment of MoS2. The fact that the TiO2 nanotubes oxidized for 4 hours with superior performance indicates a significant enhancement of the effective oxide surface area, as well as the formation of rampant surface defects that may facilitate adsorption of target molecules, which is beneficial for the gas sensing properties of the TiO2 NTs. This revision has been added on P. 5, L. 192-196.
12- Further discussion on the factors influencing these response dynamics, such as surface reactivity and gas diffusion kinetics, would enhance the understanding of the gas sensing mechanism.
A potential barrier might form at the MoS2 and TiO2 interface due to carrier trapping at the interface, and the potential barrier modulation occurred during the adsorption and desorption of NO2 might provide positive effect on the sensitivity improvement. The formation of heterojunction near the interface would contribute to the expansion of the depletion layer, which results in an increased change in resistance and enhanced sensitivity[22]. This revision has been added on P. 5, L. 210-215.
13- Elaborate on how temperature influences the adsorption and desorption processes and refer to the relevant references in the manuscript (DOI: 10.1088/1361-6528/abfd54).
At low temperatures, the gas molecules do not have sufficient thermal energy to react with the surface adsorbed oxygen species and reactions with the gas molecules occur only at the surface, while at high temperatures bulk reactions between point defects in the TiO2 lattice have a larger contribution[23]. A larger response arises from the space-charge layer due to oxygen adsorption that penetrates deeper into the TiO2 nanotubes and MoS2 can be depleted of carriers through surface interactions, which leads to an increase of the sensing properties. This revision has been added on P. 7, L. 230-236.
14- Consider discussing potential avenues for further research, such as optimizing the composite composition or exploring alternative doping materials, to enhance the gas sensing performance and address any remaining challenges.
Therefore, the application potential of TiO2 NTs/MoS2 composite extends to real-time monitoring of NO2 gas sensors as well as preservation techniques for paper books, effectively prolonging their lifespan. Potentially, functionalizing TiO2 nanotubes with MoS2, which combines the hierarchical structure of support and the unique property of MoS2, opens up new possibilities for flexible and wearable devices for various environmental sensing applications.This revision has been added on P. 8, L. 268-272.
I have made a thorough correction of the misspelling and grammatical mistakes of the manuscript as highlighted in the manuscript.
Your favorable consideration would be greatly appreciated.
Sincerely yours,
Wang-Jia
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors
The manuscript under review focuses on presenting the results of research on the development of a synthetic TiO2 NTs/CNTs composite for its use in the detection of NO2 in library air. Although in terms of the presented subject matter, it is interesting and has some development potential, before it can be approved for publication, it requires certain changes and corrections in many elements in accordance with the comments below.
Major comments:
The review of literature relating to similar issues and research works is relatively weak and requires expansion. The review should demonstrate the purposefulness of the research conducted and the justification for the development of NO2 detectors in the air. It is also worth referring to the possibility of using them in air quality monitoring in a broader context than only in assessing the threats resulting from the destructive activity of this substance to ancient books. The discussion of the results should have any reference to other already published works in this field.
It is puzzling that the authors omit the information that the sensor being developed should enable monitoring of indoor air quality, using the term "library environment monitoring". This type of imprecise formulation may cause interpretation errors and misunderstanding of its actual application.
It seems that the current title of section 2 could be changed to "Materials ad Methods". This section should be supplemented with a description of the research methodology. Any elements of the description of the research methodology included in Section 3 (Results and Discussion) should then be moved to Section 2.
At the beginning of Section 2.2 there is a description of the fabrication of gas monitoring sensors in the form of a laboratory procedure. The form of this description should be changed so that it is not a guideline, but an element of the research methodology.
NO2 concentrations of 2, 4, 6, 8, and 10 ppm in ambient (atmospheric) and indoor air practically do not occur. Have the authors tested the response recovery curves of TiO2 material for low NO2 concentrations - more similar to its content in polluted air (in the order of tenths or hundredths of ppm)? If not, it should be justified somehow and refer to the actual measurement range of the sensor being developed and the resulting possibilities of its use in air quality monitoring.
The range of NO2 concentrations presented in Figure 8 (from 168 to 1020 ppm) is extremely large, unheard of even in flue gases from combustion processes. What was the point of conducting research for such high NO2 concentrations? Would the sensor being developed also be used in flue gas monitoring?
The statement "The gas monitoring in ancient bookstores can be explained by the combination of the adsorption-desorption model and the energy band theory" (lines 190-191) suggests that the mentioned measurement principle only applies to air quality monitoring in ancient bookstores. However, the sensor being developed seems to have universal application and it should be properly described.
It is suggested that section 5 (Conclusion) be renamed "Conclusions". The statement "The gas sensor developed in this manuscript demonstrates effective detection capabilities for direct NO2 gas damage to ancient books" (lines 213-214) requires clarification and better justification in the context of the possibility of using this sensor in indoor air quality monitoring. Throughout the work, no reference is made to its measurement range and whether it is consistent with the range of NO2 concentrations potentially occurring in ancient bookstores, which is a serious oversight. Section 5 should also include a reference to the current stage of development of the developed and tested detector and whether it requires further research.
To sum up, in my opinion, the manuscript requires significant changes and supplementation with missing information in the methodological part and analysis of results. In the discussion and summary of the results, more attention should be paid to the purpose of the work and the possibilities of actual use of the developed detector in monitoring NO2 in indoor air, including in a library of ancient books. A better justification (scientific evidence) for this type of use should be included in the work. Otherwise, the purpose of the work and the sensor application should be changed.
Minor comments:
In the Abstract, the abbreviations "NO2" (line 11) and "TiO2" (line 20) should have the correct position of the number "2", which should be placed in the subscript.
The method of citing source materials from the References section should be adapted to the guidelines for authors (references [...] should be placed directly in the text and not in the superscript).
References to figures in the text should be made using the full name "Figure ..." rather than the abbreviation "Fig. ...".
The quality (resolution) of the figures should be improved (increased).
The formatting of the References section is inconsistent in terms of bibliometric data style and does not follow author guidelines. Therefore, it requires improvement. The article mentioned in [6] requires correction in the list of authors, which is incorrect, and in the name of the journal ("Scientific Reports" instead of "Scientific reports"), as well as supplementation with the range of page numbers.
Author Response
Manuscript No.: Coatings-2950756
Title: Development and Application of a Nano-Gas Sensor for Monitoring and Preservation of Ancient Books in the Library
Dear Prof., Reviewer
I am very grateful for your review of our revised manuscript (Coatings-2950756). I have revised the paper according to the helpful comments, as follows:
Reviewer's Comments
Major comments:
The review of literature relating to similar issues and research works is relatively weak and requires expansion. The review should demonstrate the purposefulness of the research conducted and the justification for the development of NO2 detectors in the air. It is also worth referring to the possibility of using them in air quality monitoring in a broader context than only in assessing the threats resulting from the destructive activity of this substance to ancient books. The discussion of the results should have any reference to other already published works in this field.
Three references have been added and I have revised the introduction. Detection methods for these gases encompass selected ion flow tube mass spectrometry, gas chromatography-mass spectrometry, proton transfer reaction mass spectrometry, and gas sensor detection technology[3, 4]. Among these, gas sensor detection technology is gaining popularity due to its affordability and ease of use[5]. Therefore, developing rapid and accurate NO2 gas sensors with low cost, low power consumption, and excellent sensitivity is critical for gas monitoring equipment. The types of gas sensors primarily include electrochemical, contact combustion, light reaction, and metal-oxide semiconductor (MOS) gas sensors. Among these, MOS gas sensors have garnered significant attention due to their advantageous features such as portability, high sensitivity, good stability, and low preparation cost[6]. MOS sensors have been used to detect toxic and harmful gases in libraries, but the problems of low sensitivity and high operating temperature have not been completely solved.
It is puzzling that the authors omit the information that the sensor being developed should enable monitoring of indoor air quality, using the term "library environment monitoring". This type of imprecise formulation may cause interpretation errors and misunderstanding of its actual application.
There are various monitoring and controlling systems utilizing gas sensors which can be considered cyber-physical systems such as environmental monitoring and indoor air quality monitoring. These systems might consist of a single sensor device or a network of individual sensor nodes. In this work, we designed an operational gas sensor measurements, capable of both indoors and outdoors measurements. In this study, we have designed an operational and stable new gas sensor for measurement. In the subsequent work, we developed its application in indoor gas detection, particularly for the protection of ancient books in libraries. However, further optimization is needed to improve its performance in detecting low NO2 levels.
It seems that the current title of section 2 could be changed to "Materials ad Methods". This section should be supplemented with a description of the research methodology. Any elements of the description of the research methodology included in Section 3 (Results and Discussion) should then be moved to Section 2.
I have changed the title of section 2 to "Materials ad Methods".
2.2 Characterization of TiO2 NTs/CNTs
The morphology of the sample was observed and analyzed using scanning electron microscopy (SEM/EDS, XL-30, Japan). X-ray diffraction (XRD, RINT2000) was employed to analyze the phase of TiO2 NTs. In XRD measurements, a Ni-filtered Cu source with a wavelength of 1.54 nm (Kα) was used to generate X-rays and the measurements were taken between 10oand 90owith a step size of 0.01o. This revision has been added on P. 2, L. 88-92.
At the beginning of Section 2.2 there is a description of the fabrication of gas monitoring sensors in the form of a laboratory procedure. The form of this description should be changed so that it is not a guideline, but an element of the research methodology.
As pointed by the reviewer, I have revised the description of the fabrication of gas monitoring sensors.
NO2 concentrations of 2, 4, 6, 8, and 10 ppm in ambient (atmospheric) and indoor air practically do not occur. Have the authors tested the response recovery curves of TiO2 material for low NO2 concentrations - more similar to its content in polluted air (in the order of tenths or hundredths of ppm)? If not, it should be justified somehow and refer to the actual measurement range of the sensor being developed and the resulting possibilities of its use in air quality monitoring.
It is critical to investigate reliable NO2 gas sensors with superior sensing properties at low concentration for environmental protection.It has been confirmed that coupling composites can greatly improve gas sensing performance over pristine materials because of heterojunction effects and synergistic effects. Based on these design principles, the purpose of our paper is to prepare heterojunction nanocomposites and develop a sensor for book preservation based on this. The product is promising to be applied in practical NO2 monitoring and the work also opens a new route for TiO2-based hierarchical materials to detect NO2 efficiently and accurately.We will optimize the experimental parameters and sensor structure to create high-performance sensors in the future.
The range of NO2 concentrations presented in Figure 8 (from 168 to 1020 ppm) is extremely large, unheard of even in flue gases from combustion processes. What was the point of conducting research for such high NO2 concentrations? Would the sensor being developed also be used in flue gas monitoring?
The sensor was not developed to use in flue gas monitoring. Our purpose is simply to test the performance under high NO2 concentration. Our future development will focus on the stability and accuracy of devices at low concentrations. Thank you for your question.
The statement "The gas monitoring in ancient bookstores can be explained by the combination of the adsorption-desorption model and the energy band theory" (lines 190-191) suggests that the mentioned measurement principle only applies to air quality monitoring in ancient bookstores. However, the sensor being developed seems to have universal application and it should be properly described.
As pointed out by the reviewer, the statement has been revised. The gas monitoring can be explained by the combination of the adsorption-desorption model [16] and the energy band theory [17]. his revision has been made on P. 8, L. 230-231.
It is suggested that section 5 (Conclusion) be renamed "Conclusions". The statement "The gas sensor developed in this manuscript demonstrates effective detection capabilities for direct NO2 gas damage to ancient books" (lines 213-214) requires clarification and better justification in the context of the possibility of using this sensor in indoor air quality monitoring. Throughout the work, no reference is made to its measurement range and whether it is consistent with the range of NO2 concentrations potentially occurring in ancient bookstores, which is a serious oversight. Section 5 should also include a reference to the current stage of development of the developed and tested detector and whether it requires further research.
I have renamed "Conclusion" to "Conclusions" in section 5. In addition, I have deleted description "The gas sensor developed in this manuscript demonstrates effective detection capabilities for direct NO2 gas damage to ancient books". In this study, TiO2 NTs/CNTs composites were synthesized via a hydrothermal method and utilized as nano gas sensors for NO2 detection. A heterojunction junction is formed at the interface of hydrothermal synthesis of TiO2 NTs and CNTs nanocomposites which increases the Schottky barrier leading to excellent gas-sensitive performance. Future work will focus on optimizing test parameters for real-time monitoring of ancient book environments to enable timely and efficient protective measures. This revision has been made in section 5.
To sum up, in my opinion, the manuscript requires significant changes and supplementation with missing information in the methodological part and analysis of results. In the discussion and summary of the results, more attention should be paid to the purpose of the work and the possibilities of actual use of the developed detector in monitoring NO2 in indoor air, including in a library of ancient books. A better justification (scientific evidence) for this type of use should be included in the work. Otherwise, the purpose of the work and the sensor application should be changed.
Minor comments:
In the Abstract, the abbreviations "NO2" (line 11) and "TiO2" (line 20) should have the correct position of the number "2", which should be placed in the subscript.
I have revised the corresponding abbreviations and subscript in the Abstract.
The method of citing source materials from the References section should be adapted to the guidelines for authors (references [...] should be placed directly in the text and not in the superscript).
I have revised the citing format throughout the manuscript.
References to figures in the text should be made using the full name "Figure ..." rather than the abbreviation "Fig. ...".
I have replaced “Fig.” by “Figure” throughout the manuscript.
The quality (resolution) of the figures should be improved (increased).
I have increased the figures in the manuscript.
The formatting of the References section is inconsistent in terms of bibliometric data style and does not follow author guidelines. Therefore, it requires improvement. The article mentioned in [6] requires correction in the list of authors, which is incorrect, and in the name of the journal ("Scientific Reports" instead of "Scientific reports"), as well as supplementation with the range of page numbers.
I have revised the formatting of the References and journal name of reference [6].
I have made a thorough correction of the misspelling and grammatical mistakes of the manuscript as highlighted in the manuscript.
Your favorable consideration would be greatly appreciated.
Sincerely yours,
Wang-Jia
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for Authors
The authors took into account all my comments and significantly improved the article.
Author Response
Dear Prof., Reviewer
I am very grateful for your review of our revised manuscript (Coatings-2950756R1). I have revised the paper according to the helpful comments, as follows:
Reviewer's Comments
The authors took into account all my comments and significantly improved the article.
Thanks again for your help.
Your favorable consideration would be greatly appreciated.
Sincerely yours,
Wang-Jia
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors
I would like to thank the authors of the manuscript for including most of the comments contained in my review in its revision version and for answering some questions and doubts. Not all of them have been fully resolved, but they can be considered quite satisfactory due to the corrections made to the manuscript. Nevertheless, the authors of the manuscript should somehow refer in their work to the detection threshold of the NO2 sensor being developed and the possibility of its use in air quality monitoring (including indoor air quality).
Before allowing for publication, I also suggest making minor editorial corrections:
- it is necessary to improve the formatting of the text style of the title of section 2.2 (Italic font) and the too small paragraph indent of this section (lines 86-90);
- the number "2" in the abbreviation "TiO2" in the extended description of Figure 1b (line 106) should be placed in the subscript ("TiO2");
- some references to figures in the text ("Figures" instead of "Fig." in several places) should also be changed (lines 118, 161, 201);
- in the description of Figure 2 after "temperatures" (line 121) it is suggested to use a colon (:) instead of a dot;
- in the changed description of Figure 3, a colon (:) should be inserted after "temperatures" (line 141);
- the missing markings (a) and (b) should be inserted under the components of Figure 8;
- in general, the way of placing the markings (a), (b), etc. on other multi-element figures differs from the guidelines for authors;
- the formatting of the References section should be unified and better aligned with the guidelines for authors.
Author Response
Dear Prof., Reviewer
I am very grateful for your review of our revised manuscript (Coatings-2950756R1). I have revised the paper according to the helpful comments, as follows:
I would like to thank the authors of the manuscript for including most of the comments contained in my review in its revision version and for answering some questions and doubts. Not all of them have been fully resolved, but they can be considered quite satisfactory due to the corrections made to the manuscript. Nevertheless, the authors of the manuscript should somehow refer in their work to the detection threshold of the NO2 sensor being developed and the possibility of its use in air quality monitoring (including indoor air quality). Before allowing for publication, I also suggest making minor editorial corrections:
According to the reviewer's suggestion, we revised the introduction and added three references. Zhao et al. synthesized In2O3 nanowires through solvothermal method, which showed a high response value of 54.6 to 1 ppm NO2 at 150oC [10]. Liu et al. utilized the atomic layer deposition to prepare sensor fabricated on nanotubes, which exhibited good response and acceptable response time of 65 s to 0.5 ppm NO2 under UV illumination [11]. However, the above reported methods for nanostructured materials have weaknesses of intricate manipulation, the usage of UV illumination and noble metals also increases in sensor costs [12]. Hence, It is necessary to invent the NO2 sensor that can quickly and sensitively detect the trace amount of NO2 in the air at low operating temperature. This study has the potential to decrease production expenses and this sensor can be potentially applied for rapidly and precisely detecting NO2 in air quality monitoring. Future work will focus on optimizing test parameters for real-time monitoring air quality. This revision has been added on P. 2, L. 55-63.
- it is necessary to improve the formatting of the text style of the title of section 2.2 (Italic font) and the too small paragraph indent of this section (lines 86-90);
I have revised the formatting of the text style of the title of section 2.2 (Italic font) and the too small paragraph indent of this section (lines 86-90).
- the number "2" in the abbreviation "TiO2" in the extended description of Figure 1b (line 106) should be placed in the subscript ("TiO2");
I have changed "TiO2" to "TiO2" in line 106.
- some references to figures in the text ("Figures" instead of "Fig." in several places) should also be changed (lines 118, 161, 201);
I have revised "Fig." by "Figures" in lines 118, 161 and 201.
- in the description of Figure 2 after "temperatures" (line 121) it is suggested to use a colon (:) instead of a dot;
As pointed out by the reviewer, I have corrected this point.
- in the changed description of Figure 3, a colon (:) should be inserted after "temperatures" (line 141);
As pointed out by the reviewer, I have corrected this point.
- the missing markings (a) and (b) should be inserted under the components of Figure 8;
I have inserted (a) and (b) in Figure 8.
- in general, the way of placing the markings (a), (b), etc. on other multi-element figures differs from the guidelines for authors; the formatting of the References section should be unified and better aligned with the guidelines for authors.
I have unified the formatting of the References section follow the guidelines for authors.
Your favorable consideration would be greatly appreciated.
Sincerely yours,
Wang-Jia
