Electrospinning-Based Carbon Nanofibers for Energy and Sensor Applications
Round 1
Reviewer 1 Report
A interesting review paper. It was well prepared and recommend to accept as it is.
Some suggestions to the manuscript:
1. Page 3, in set up of electrospinning system, for vaporization of solvent with heat of lamp, is it a close system? Otherwise, there is a concern of environmental pollution.
2. For PAN, PVA abbreviations, better to spell them out first.
Author Response
COMMENT
A interesting review paper. It was well prepared and recommend to accept as it is.
RESPONSE:
We highly appreciate your positive comments on our manuscript.
COMMENT 1) Page 3, in set up of electrospinning system, for vaporization of solvent with heat of lamp, is it a close system? Otherwise, there is a concern of environmental pollution.
RESPONSE:
Thank you for your question. Unfortunately, the system cannot be built in a closed system because the vaporization needs to be maintained stable, which can be affected by the concentration of vaporized solvent in the environment. The solvent after vaporizing will be released into the environment. However, since the spinning speed is very slow, the concentration of the vaporized solution in the air is also low. The additional information was added to the manuscript.
Revised parts in the manuscript
(1) The sentences “It is noted that the vaporized solvent will be released into the surrounding environment. Though it may cause air pollution, the spinning speed is so slow that it became inconsiderable factor. On the other side, the electrospinning system can be installed in a fume hood, which can further reduce the effect of the electrospinning on environment.” was added to the revised manuscript. (see Line 87, Page 2)
COMMENT 2) For PAN, PVA abbreviations, better to spell them out first.
RESPONSE:
Thank you for your recommendation. As you mentioned, we added full name of PAN (polyacrylonitrile) and PVA (polyvinyl alcohol) in the revised manuscrtipt.
Revised parts in the manuscript
(1) The sentence “PAN has been used as a precursor for many carbon materials because of its unique properties including hardness, relative insolubility, and high-melting temperature [35].” was changed to “Polyacrylonitrile (PAN) has been used as a precursor for many carbon materials because of its unique properties including hardness, relative insolubility, and high-melting temperature [35].” in the revised manuscript. (see Line 103, Page 3)
(2) The sentence “Research on PVA based CNFs began in the 60s of the 20th century [41].” was changed to “Research on polyvinyl alcohol (PVA) based CNFs began in the 60s of the 20th century [41].” in the revised manuscript. (see Line 121, Page 04)
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The revised parts were highlighted by yellow background color. Thank you for your critical and valuable comments again.
Sincerely,
Prof. Junseop Lee
Author Response File: 
Author Response.doc
Reviewer 2 Report
The authors comprehensively present the recent progresses of Electrospinning Based Carbon Nanofibers for Energy and Sen-2 sor Application. The paper is well organized and clearly presented. I recommend publication.
Author Response
COMMENT
The authors comprehensively present the recent progresses of Electrospinning Based Carbon Nanofibers for Energy and Sen-2 sor Application. The paper is well organized and clearly presented. I recommend publication.
RESPONSE:
We highly appreciate your positive comments on our manuscript.
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The revised parts were highlighted by yellow background color. Thank you for your critical and valuable comments again.
Sincerely,
Prof. Junseop Lee
Author Response File: Author Response.doc
Reviewer 3 Report
The article is well written,
goal and the novelty are not clear.
The method is almost clearly presented, but rev suggests to improve it.
The results are presented in a not sufficiently detailed way.
Specify in the Abstract the objective of the paper
Enlighten the novelty of the work
Figures and Tables should always be cited in the text and briefly described.
A brief description of the cooling system needed
The advantages of the proposed method should be discussed precisely
Author Response
COMMENT
The article is well written, goal and the novelty are not clear.
RESPONSE:
We highly appreciate your positive comments on our manuscript. We tried our best to improve the manuscript.
COMMENT 1) The method is almost clearly presented, but rev suggests to improve it.
RESPONSE:
Thank you for your comment about electrospinning technique. The concept of electrospinning is the attraction force between the positive and negative electrode, which was applied to the needle and collector of the electrospinning. Since they are fitted in positions, the charged polymer solution is pulled down to the collector in a flow, which is reshaped into fibers after the solvent is removed. When polymer precursors of carbon material are used in an electrospinning system, the polymer fibers can be carbonized into a sp2 carbon structure with a suitable carbonization process. However, in addition to the advantages of a simple process, solvent vapor affects the environment. Additional information on the vaporized solvent had been added.
Revised parts in the manuscript
(1) The sentences “It is noted that the vaporized solvent will be released into the surrounding environment. Though it may cause air pollution, the spinning speed is so slow that it became an inconsiderable factor. On the other side, the electrospinning system can be installed in a fume hood, which can further reduce the effect of the electrospinning on the environment.” were added in the revised manuscript. (see Line 87, Page 2)
COMMENT 2) The results are presented in a not sufficiently detailed way.
RESPONSE:
Thank you for your comment about more detailed result. We classified the electrospinning techniques based on the changes in the structure of the fibers during the carbonization process as well as the modifications that were carried out on the nozzle of the system. Many modifications have been done with the electrospinning processes to alter the structure of the nanofiber. The addition of metal salt or another kind of polymer can create porous structure with generation of inorganic particles in the carbon structure. These modifications can greatly enhance the pore volume, surface area, as well as working performance of the material. On the other side, the existence of many ingredients can bring difficulties during the spinning and carbonization, which is in needs to be mentioned in the manuscript. Additional information about electrospinning has been added to the manuscript.
Revised parts in the manuscript
(1) The sentence “Though the common electrospinning can manufacture CNFs easily with high uniformity, the material has a low surface area and porous volume, thus they have low working performance in the applications of carbon materials.” was added in the revised manuscript. (see Line 231, Page 8)
(2) The sentences “The electrospinning using the combination of the precursor of carbon and secondary materials can significantly alter the physical structure of CNFs, which lead to the improvement of working capacitance of the carbon material. However, the surface tension between the ingredients can result in many difficulties for the spinning process.” were inserted in the revised manuscript. (see Line 277, Page 10)
COMMENT 3) Specify in the Abstract the objective of the paper
RESPONSE:
Thank you for your comment about objective of the paper. As you mentioned, we added object of this paper that is content about generation of advanced carbon nanofibers using diverse electrospinning techniques in the revised abstract part.
Revised parts in the manuscript
(1) The sentences “In this review article, we introduce an electrospinning method capable of manufacturing CNFs and present precursor polymers for carbon capable of forming CNFs. Thereafter, the technology of manufacturing CNFs having a porous and hollow structure by modifying the existing electrospinning technology is presented” were modified to “In this review article, we present a method and generation mechanism for manufacturing uniform CNFs using conventional electrospinning. Thereafter, a method of maximizing the surface area by changing the structure of the CNFs using the modified electrospinning thchnique is presented. Furthermore, a process of forming CNF-based nanocomposites using advanced electrospinning is also proposed.” in the revised abstract part. (See line 12, page 1)
COMMENT 4) Enlighten the novelty of the work
RESPONSE:
Thank you for your comment about novelt of the paper. The review article focus on the carbon nanofibers manufacturers from the electrospinning method and the various modifications that were done in order to create carbon nanofibers with high working performance. Furthermore, the diversity of applications of the carbon nanofibers made with the electrospinning method has also been discussed as examples of the outstanding properties of materials.
Revised parts in the manuscript
(1) The sentence “While the common electrospinning can produce a large number of uniform polymer fibers, which act as the precursor for carbon. The combination of different materials can greatly alter the structure of CNFs and its properties for the desired applications.” was added in the introduction of the revised manuscript. (See Line 65, Page 2)
COMMENT 5) Figures and Tables should always be cited in the text and briefly described.
RESPONSE:
Thank you for your recommendation. We had checked and revised all error in the manuscript.
COMMENT 6) A brief description of the cooling system needed
RESPONSE:
Thank you for your comment about cooling system. As far as we know, the cooling system is unnecessary in a electrospinning system because the system’s operation only reduce a small amount of heat.
Revised parts in the manuscript
(1) The sentence “In addition, the electrospinning system working temperature is not high, hence it does not require any cooling system.” was added to the revised manuscript. (See Line 98, Page 3)
COMMENT 7) The advantages of the proposed method should be discussed precisely
RESPONSE:
Thank you for your comment about advantages of the electrospinning. The electrospinning techniques were classified based on the changes in the structure of the fibers during the carbonization process, as well as the modifications that were carried out on the nozzle of the system.
The common electrospinning which uses a single nozzle can fabricate a large number of uniform nanofibers. Though the electrospinning and carbonization processes can be carried out easily, the structure of the generated carbon nanofiber is so simple that the surface area and pore volume cannot be good enough for the requirements in advanced applications.
To improve the working performance of the material, modifications have been done to the electrospinning:
(1) The polymer precursor of carbon can be mixed and electrospun together with another polymer which can be generate phase separated polymer nanofiber. After carbonization process, the final carbon nanofibers can carry porous, or channel structures, which greatly improve the pore volume and surface area of the carbon material.
(2) Not only is the dual-nozzle electrospinning able to create the hollow structure for the carbon nanofibers, but it can also be used to decorate particles on the inner wall of the hollow fibers. The inner particles possess higher stability during long-time operation thanks to the protection of the carbon. The dual-nozzle electrospinning requires a lot of optimization in spinning operation and carbonization to acquire uniform carbon nanofibers.
(3) The solution of polymer precursor can be added with the salt of metal (such as Ni, Co, Ti) to form inorganic component in the carbon structure. However, the reaction of the salt can damage the structure of carbon nanofiber. To protect collapse of the carbon structure, advanced electrospinning technique was suggested.
Since there is a need for improvement in the discussion of electrospinning advantage, the following sentences were added to the revised manuscript.
Revised parts in the manuscript
(1) The sentences “Electrospinning can create a large number of precursor fibers for the fabrication of CNFs with high uniformity. There exist advanced modifications of the electrospinning technique that allows the user the manually create pore, hole, channel, or decorate metal/metal oxide in the nanostructure of the CNFs.” were added in the revised manuscript. (see Line 94, Page 2)
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The revised parts were highlighted by yellow background color. Thank you for your critical and valuable comments again.
Sincerely,
Prof. Junseop Lee
Author Response File: Author Response.doc
