Plasma Synthesis and Characterization of PANI + WO3 Nanocomposites and their Supercapacitor Applications
Round 1
Reviewer 1 Report
In this manuscript, the authors proposed a method to prepare PANI-WO3 composites, characterized the samples, and tried to apply the composites as the electrode materials in supercapacitors.
There are several aspects must be improved.
The are some careless mistakes through the manuscript. For example, the name of the composites, subscripts for chemical formulas, and the name of the chemicals , the symbol of angle theta, etc., were not unified; some sentences were repeated (line 68-73, page 2).
Please show the calculation of the concentrations of WO3 in the composites. Were the masses divided by two before divided by the mass of PANI? Why?
What is the specification of the steel substrate?
The composite materials were deposited onto the steel substrate via dip-and-dry method. The resistance on the interface would be a significant drawback in a supercapacitor electrode, which maybe a possible reason for the poor electrochemical performance.
Please add the reference for the discharge and active burning time of the impulse.
In the introduction, it is said “During the plasma chemical treatment, 64 new oxygen-containing functional groups are formed and polymer crosslinking and de-65 composition processes take place.” However, PANI was not destructed in this research according to the IR spectra. Why?
Please use the same scale bars for TEM images.
The captions for figures should be more detailed.
The focus of this manuscript is the application of the composite material as supercapacitor electrode materials. However, apparently, CV, as the only the electrochemical characterization, is not enough for this purpose. CD, impedance, etc., should be used to character the material more thoroughly.
Why the voltage windows of CV tests were not the same?
The specific capacitance is very low compared to the peer research. The preparation of the composites or the fabrication of the electrodes must be improved.
Overall, the PANI-WO3 composites were properly synthesized and the chemical composition of the composites were carefully characterized. But the electrochemical performance was poorly tested. The capacitance is not comparable to peer works. The presentation needs to be improved. I would say reconsider this manuscript after Major Revisions.
Author Response
- The are some careless mistakes through the manuscript. For example, the name of the composites, subscripts for chemical formulas, and the name of the chemicals , the symbol of angle theta, etc., were not unified; some sentences were repeated (line 68-73, page 2).
Reply: We agree with the reviewer's remark; corrections have been made to the text of the manuscript.
- Please show the calculation of the concentrations of WO3 in the composites. Were the masses divided by two before divided by the mass of PANI? Why?
Reply: Thanks for the comment. The calculation formula has been added to the text of the manuscript. The division was made by the mass of the polymer.
- What is the specification of the steel substrate?
Reply: The substrate specimen size was 60 mm × 15 mm × 3 mm, steel grade AISI 201. Corrections have been made to the text of the manuscript.
- The composite materials were deposited onto the steel substrate via dip-and-dry method. The resistance on the interface would be a significant drawback in a supercapacitor electrode, which maybe a possible reason for the poor electrochemical performance.
Reply: We agree with the reviewer's remark, however, at this stage of the research, this method of preparing samples for electrochemical studies was chosen due to the ease of manufacture.
- Please add the reference for the discharge and active burning time of the impulse.
Reply: Thank you for your comment, corrections have been made to the text of the manuscript.
- In the introduction, it is said “During the plasma chemical treatment, 64 new oxygen-containing functional groups are formed and polymer crosslinking and de-65 composition processes take place.” However, PANI was not destructed in this research according to the IR spectra. Why?
Reply: The formation of oxygen-containing groups and destruction of the polymer is observed with a longer plasma treatment time (more than 15 minutes). But the treatment time was only 5 minutes in our experiments. This time is sufficient to obtain the required amount of metal oxide nanoparticles, which will be incorporated into the polymer matrix.
- Please use the same scale bars for TEM images.
Reply: Corrections have been made to the figure.
- The captions for figures should be more detailed.
Reply: In order not to clutter up the captions to the figures with the same sentences, we decided to make them more concise. All the necessary information is presented directly in the figures.
- The focus of this manuscript is the application of the composite material as supercapacitor electrode materials. However, apparently, CV, as the only the electrochemical characterization, is not enough for this purpose. CD, impedance, etc., should be used to character the material more thoroughly.
Reply: We have redesigned the sample volt-ampere curves more accurately and thoroughly and added charge-discharge cycle data for the samples.
- Why the voltage windows of CV tests were not the same?
Reply: This indicates that the reaction kinetics were surface-limited, and that the electrochemical properties were determined not only by the nature of the polymer matrix, but also by the metal oxide.
- The specific capacitance is very low compared to the peer research. The preparation of the composites or the fabrication of the electrodes must be improved.
Reply: Thank you for your comment. Experiments have been redone.
Author Response File: 
Author Response.doc
Reviewer 2 Report
Manuscript entitled "Plasma synthesis and characterization of PANI-WO3 nano- composites and its supercapacitor application", a PANI-WO3 nanocomposites prepared by underwater impulse discharge methods could be a promising candidate as an electrode material for high-power supercapacitor. This study shows excellent electrochemical and optical properties, providing a promising electrode material for future high power supercapacitors. Over all, this is a topic of interest to readers in the related areas, it is recommended to publish a manuscript.
Reviewer evaluation:
The paper is well written and researched，There are some incorrect places in the arrangement of the text. In addition to writing in English, there are some other minor issues with formatting in the manuscript. The following suggestions should be carefully considered during the revisions.
Review suggestions:
1. Please add the results of the specific surface area test (BET), which corroborates the SEM images and further proves the authors' point.
2. The Galvanostatic charge/discharge test allows an in-depth study of the electrochemical properties of this electrode material.
3. There are some small mistakes in this manuscript and need more corrections. The article title is “supercapacitor” and the abstract is “capacitor”, please unify the terminology name and explain clearly, on page 1 line 19.
4. There should be a space between numbers and units, for example, on page 2 line 93 “25℃” should be “25 ℃”. Please check the full text.
5. Please note that the numbers in the chemical formula need to be subscripted. For example, on page 1 line 44 “WO3” should be “WO3” Please check the full ext.6. Please keep the material and test terms consistent throughout the text. For example, the material synthesized in the title is “PANI-WO3”, is inconsistency in the text， “PANI-WO3” on page 1 line 16 and “WO3/PANI” on page 2 line 53. Please be consistent with, “UV-vis” on page 5 line 186(Figure 2) and “UV/vis” on page 5 line 180 as well. Please check the full text.
7. It is recommended to adjust the picture parameters to make the picture more readable. For example, modify the picture axis scale to 4-6 and add right axis and upper axis scale lines.
8. Please explain the “´” in equation 1 on page 5 line 198.
9. The format of all references should be the same, please check carefully and correct..
10. Most recently, the development of highly efficient elctrodes attracts great interest for supercapacitors, e. g. Rare Metals. 40, 440–447 (2021); Rare Metals 41, 2230–2236 (2022); Mater. Horiz., 2020,7, 495-503. These related publications should be involved and summarized in the background of this work.
Author Response
- Please add the results of the specific surface area test (BET), which corroborates the SEM images and further proves the authors' point.
Reply: The specific surface area test was performed, information added to the manuscript
- The Galvanostatic charge/discharge test allows an in-depth study of the electrochemical properties of this electrode material.
Reply: Thanks for the comment. Additional electrochemical measurements were performed and the information added to the text of the manuscript.
- There are some small mistakes in this manuscript and need more corrections. The article title is “supercapacitor” and the abstract is “capacitor”, please unify the terminology name and explain clearly, on page 1 line 19.
Reply: Thanks for the comment. All fixes have been made.
- There should be a space between numbers and units, for example, on page 2 line 93 “25℃” should be “25 ℃”. Please check the full text.
Reply: Thanks for the comment. All fixes have been made.
- Please note that the numbers in the chemical formula need to be subscripted. For example, on page 1 line 44 “WO3” should be “WO3” Please check the full ext.
Reply: Thanks for the comment. All fixes have been made.
- Please keep the material and test terms consistent throughout the text. For example, the material synthesized in the title is “PANI-WO3”, is inconsistency in the text， “PANI-WO3” on page 1 line 16 and “WO3/PANI” on page 2 line 53. Please be consistent with, “UV-vis” on page 5 line 186(Figure 2) and “UV/vis” on page 5 line 180 as well. Please check the full text.
Reply: Thanks for the comment. All fixes have been made.
- It is recommended to adjust the picture parameters to make the picture more readable. For example, modify the picture axis scale to 4-6 and add right axis and upper axis scale lines.
Reply: Thanks for the note, some Figures have been corrected.
- Please explain the “´” in equation 1 on page 5 line 198.
Reply: This is a typo, the symbol has been removed.
- The format of all references should be the same, please check carefully and correct.
Reply: Thanks for the comment. All fixes have been made.
- Most recently, the development of highly efficient elctrodes attracts great interest for supercapacitors, e. g. Rare Metals. 40, 440–447 (2021); Rare Metals 41, 2230–2236 (2022); Mater. Horiz., 2020,7, 495-503. These related publications should be involved and summarized in the background of this work.
Reply: Thanks for the very interesting references, the bibliography has been corrected.
Author Response File: Author Response.doc
Reviewer 3 Report
This work presents some interesting concepts and the authors have extensively characterized the materials using a wide range of methodologies. However, I recommend that this work is not suitable for publication until the following revisions have been made, particularly with the electrochemical characterization and results interpretation.
· The pi-pi* absorption of PANI in Figure 2a at 550nm is quite unclear and hard to compare from a reader’s point of view. Can the authors make this clearer and distinguish the differences in intensities between the 3 samples?
· The differences between the three samples in Figure 5 is also unclear. The authors should outline the presence of WO3 in these SEM images. Can energy dispersive X-ray spectroscopy (EDS) be used to show this?
· The authors should compare and discuss the electrochemical performance of their PANI/WO3 samples with previous work in the literature. Other literature values of supercapacitor electrodes manufactured with metal oxides and polymer show specific capacitance values between 100 F/g and 700 F/g. These electrochemical results do not appear significant enough for publication. In addition, the correlation between electrochemical performance and morphological characteristics from SEM/TEM should be discussed.
· Electrochemical calculations using equation 4 only calculate instantaneous capacitance which is not the correct way to measure the capacitance of this material. Capacitance must be calculated using the integration of the area under the discharge curve, divided by the voltage rate and difference in voltage. Please see equation 133 in Noori et al. - 2019 - Towards establishing standard performance metrics for batteries, supercapacitors and beyond.
· Description of the samples and method of the electrochemical analysis should be presented. The reader cannot understand the size, weight or geometry of your electrode, or the electrochemical cell, electrolyte and potentiostat used for this analysis.
· The rate capability of this electrode material should be tested and presented preferably by galvanostatic charge-discharge cycles.
Author Response
- The pi-pi* absorption of PANI in Figure 2a at 550nm is quite unclear and hard to compare from a reader’s point of view. Can the authors make this clearer and distinguish the differences in intensities between the 3 samples?
Reply: It should be noted that the peak at 550 nm is not very marked due to the low concentration of PANI in the aqueous dispersion. The resulting tungsten oxide nanoparticles increase the absorption intensity of the samples, so the peak at 550 nm is leveled.
- The differences between the three samples in Figure 5 is also unclear. The authors should outline the presence of WO3 in these SEM images. Can energy dispersive X-ray spectroscopy (EDS) be used to show this?
Reply: It should be noted that the tungsten oxide particles are mostly embedded in the polymer matrix, so they are not present in the SEM images. Particles of tungsten oxide are clearly visible on TEM images. SEM analysis proves the preserved globular structure of PANI. We will not have time to perform the EDS analysis due to the short response time to the review.
- The authors should compare and discuss the electrochemical performance of their PANI/WO3 samples with previous work in the literature. Other literature values of supercapacitor electrodes manufactured with metal oxides and polymer show specific capacitance values between 100 F/g and 700 F/g. These electrochemical results do not appear significant enough for publication. In addition, the correlation between electrochemical performance and morphological characteristics from SEM/TEM should be discussed.
Reply: We agree with the Reviewer's remark. Electrochemical measurements have been redone. Details of the experiment and discussion have been added to the text of the manuscript.
- Electrochemical calculations using equation 4 only calculate instantaneous capacitance which is not the correct way to measure the capacitance of this material. Capacitance must be calculated using the integration of the area under the discharge curve, divided by the voltage rate and difference in voltage. Please see equation 133 in Noori et al. - 2019 - Towards establishing standard performance metrics for batteries, supercapacitors and beyond.
Reply: Thanks for the comment. All fixes have been made.
- Description of the samples and method of the electrochemical analysis should be presented. The reader cannot understand the size, weight or geometry of your electrode, or the electrochemical cell, electrolyte and potentiostat used for this analysis.
Reply: Thanks for the comment. All fixes have been made.
- The rate capability of this electrode material should be tested and presented preferably by galvanostatic charge-discharge cycles.
Reply: Thanks for the comment. Additional measurements were taken and the results added to the text of the manuscript.
Author Response File: Author Response.doc
Round 2
Reviewer 1 Report
Changes were made to address most of the reviewer's questions. I agree to publish this version.
Reviewer 2 Report
acceptance
Reviewer 3 Report
The authors have made changes to the manuscripts to address most of my comments. I recommend publication of manuscript in its current form.
