Hydrophilic Surface Treatment of Carbon Powder Using CO2 Plasma Activated Gas
Round 1
Reviewer 1 Report
Congratulations on a well-written manuscript. My comments can be found in the attached file.
Comments for author File: 
Comments.pdf
Author Response
- Lines 8 & 9: The first sentence states that “carbon powders have characteristics….” The following sentence begins “Due this property…”. The problem is that “characteristics” is plural, and “this property” is singular. A possible fix might be to change the second sentence to “The electrical conductivity causes to carbon powder to agglomerate…
Previous: “Carbon powders have characteristics that exhibit electrical conductivity. Due to this properties, when used for surface treatments with plasma sources, it causes the carbon powder to agglomerate due to the applied electrostatic forces and discharge capacitance.”
Revision: Carbon powders exhibit electrical conductivity that causes the powders to agglomerate due to the applied electrostatic forces and discharge capacitance, when used for surface treatments with plasma sources.
- This rewording also eliminates the need to use the bland “it is…” phrase. This is also an issue in the Introduction, where “it is” occurs twice in close succession (lines 27, 28), This is a small issue, but for many years I have been advising authors that these bland phrases can always be worded in a more effective way. In the first instance, the sentence could be restructured to something like “The carbon powder has low surface energy due to the C-C bonds because it is manufactured with almost n functional groups”.
As suggested by the reviewer, the sentence has been changed to “The carbon powder has low surface energy due to the C-C bonds because it is manufactured with almost no functional groups.”.
Materials and Methods:
- Line 64: “The sample have…” is a mix of singular and plural. Correct form would be either “samples have..” or “sample has”.
As suggested by the reviewer, the sentence has been changed to “sample has ~”.
Results and Discussion:
- Line 156. “One can conclude” seems like an unnecessary statement. The “one” is a mystery person. A clearer statement would be to state that “We observed…”, but I think it would be adequate to simply say “As plasma time increases, the sedimentation time becomes longer.
As suggested by the reviewer, the sentence has been changed to “As plasma time increases, the sedimentation time becomes longer.”
Conclusions:
- Line 227. “PAG treated carbon powder shows good properties of wettability properties”
The most obvious problem is the redundant use of “properties”. I also suggest that “good” is a term that should generally be avoided in scientific writing because the term implies a moral judgement (“good” versus “bad”). A more neutral alternative would be something like “The wettability properties make PAG treated carbon powder a useful product for water-based dispersion and water-based slurry production.”
As suggested by the reviewer, the sentence has been changed to “The wettability properties make PAG treated carbon powder a useful product for water-based dispersion and water-based slurry production.”
- As a minor point, the presentation of SEM/EDX data (Figure 6) presents oxygen and carbon values with a purported accuracy of two decimal places. However, the EDX quantification of both these elements is rather poor because of the difficulty of measuring X-ray fluorescence intensities of these very light elements. My experience with several SEM/EDX instruments is that values for carbon are commonly calculated significantly higher than the actual value. It is certainly not possible to calculate percentages to two (or even one) decimal place. However, in this case the importance of the results is the marked difference in C:0 ratios between the treated and untreated samples, which is evident simply from the peak height ratios. I similarly doubt that XPS spectral results can be calculated to two decimal places, but again, the general trends are evident.
As the reviewer has indicated, we also believe that it is not accurate to the two decimals. In the data, we wanted to present the raw data as it is from the measurement device of SEM/EDX, as to show that a conclusion can be drawn on the general trend of O/C ratio between untreated and the treated samples.
Author Response File: Author Response.pdf
Reviewer 2 Report
In this manuscript, the authors attempted successfully to change the wettability of carbon powders using a plasma gas. Several advanced techniques were used to assess the properties of the treated particles, including changes in chemical composition and wetting properties. The results clearly show the chemical modifications that occurred and their effect on the desirable change of the surface to more wettable (i.e. more hydrophilic). My main suggestion is that the authors consider using TEM and pore size distribution by N2 adsorption to better characterize the surface changes that occurred (if the authors are able to provide these data soon). The authors are also encouraged to add to the conclusions ideas about the application of these treated powders, and link the findings to the knowledge gaps identified in other studies. In fact, looking at the references, it would be good if the authors can cite a larger number of recent papers, and it is important to connect the new research to recent research to increase discoverability of the article through citation networks. Overall, it is a thoughtful study with valuable findings.
Author Response
- My main suggestion is that the authors consider using TEM and pore size distribution by N2 adsorption to better characterize the surface changes that occurred (if the authors are able to provide these data soon).
Unfortunately, we were unable to use TEM, which takes about more than a month after making a reservation for usage. If making a prediction on the measurement, it would most likely be a partially formation of a very thin oxide layer.
We cannot measure the pore size distribution by N2 adsorption. In its place, we used a BET surface area measurement. The following is a table of our measurement.
BET surface area analysis on the carbon powder shows small reduction. After 20 min of treatment at 1236 m2/g, the reduction is shown to be saturated.
The carbon powder used is EC600JD, in which from the manufacturer data https://www.lion-specialty-chem.co.jp/en/product/carbon/carbon01.htm) shows that the BET surface area (m2/g) is 1270 m2/g. When considering possible deviation of this value, we think that the surface area has little change from the PAG treatment. We also believe that this trend should be similar on the pore size distribution.
- The authors are also encouraged to add to the conclusions ideas about the application of these treated powders, and link the findings to the knowledge gaps identified in other studies. In fact, looking at the references, it would be good if the authors can cite a larger number of recent papers, and it is important to connect the new research to recent research to increase discoverability of the article through citation networks. Overall, it is a thoughtful study with valuable findings.
We sincerely like to thank you for the advice. In the conclusions, we have added the following sentence at the end.
“The wettability properties make PAG treated carbon powder a useful product for water-based dispersion and water-based slurry production [28-30].”
In addition, three References has been added at the conclusion to show the possible applicability of carbon powder with wettability properties [28-30]
R28] Using graphene powder and carbon black to manufacture conductive ink that is applied to screen printing inks.
R29] Carbon-based aqueous inks are applied on wearable electronics, electroluminescent (EL) devices and sensors, which can enhance the dispersion stability.
R30] For Lithium ion batteries (LIBs) that presently uses process on NMP-based systems, if overcoming difficulties for plasma treated powders that have poor wetting , an Aqueous slurry can be in usage for preparation.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
accept
