The Effect of High-Energy Ball Milling Conditions on Microstructure and Hydrogen Desorption Properties of Magnesium Hydride and Single-Walled Carbon Nanotubes

Round 1

Reviewer 1 Report

• The innovation of this paper is insufficient;
• The scales in different SEM images in the manuscript are inconsistent，therefore, It is difficult to distinguish the difference of particle shape after different ball milling time；
• “Thus, the intensity of diffraction peaks corresponding to the β-MgH2 phase slightly decreases when the speed is varied from 300 to 900 rpm. This may be due to the destruction of large particles and the formation of small ones.”Please verify whether“ the destruction of large particles and the formation of small ones”will cause“the intensity of diffraction peaks corresponding to the β-MgH2 phase slightly decreases”to happen?
• “The diffraction peaks corresponding to carbon structures were not found in all diffraction patterns of the composites”，So where did carbon go?

Author Response

Dear Reviewer:

Please find attached for your kind review our manuscript after revision entitled “The effect of high-energy ball milling conditions on microstructure and hydrogen desorption properties of magnesium hydride and single-walled carbon nanotubes”.

We have changed the following points and marked it by color in paper:

1. In the research work, novelty was highlighted. We have analyzed a large number of articles and research papers, only a small part of the literature review is presented in the introduction. In our case, the novelty consists in the unambiguous determination of the influence of such parameters as the time and speed of milling on the hydrogen desorption properties of MgH₂–carbon nanotubes composites. The fact is that after analyzing the literature, we got an incomplete understanding of how these parameters can affect the presented properties. Some authors say that it takes tens of hours of milling to obtain a catalytic effect; other researchers indicate that positive results are achieved after several tens of minutes with comparable grinding speed parameters. There are also authors who argue that carbon nanomaterials have no catalytic effect at all. Therefore, we decided to conduct our own study in order to determine the influence of the listed parameters on the activation energy and the temperature of hydrogen desorption.
2. The scales of the compared SEM images has been corrected.
3. The suggestion that the decrease in the intensity of the diffraction peaks is due to the destruction of larger particles has been corrected. The diffraction pattern is analyzed and the fact is concluded that there was also a slight broadening of the peaks. This fact was justified by a decrease in the size of crystallites, defects and the appearance of internal stresses in the crystal lattice. Literature references also were given.
4. In the case of diffraction patterns of obtained composites, the carbon peak is absent, since it was insignificantly expressed in the diffraction pattern of the carbon nanotubes themselves (Tuball^ТМ by "‎OCSiAl"‎ company). An experimentally obtained X-Ray diffraction pattern of carbon nanotubes that used in the study was presented. Also cited is a literature source in which the diffraction pattern coincides with our data.

Look forward to your favorable consideration.

Most sincerely,

Viktor Kudiiarov, PhD.

National Research Tomsk Polytechnic University

[email protected]

89138700989

Reviewer 2 Report

"The effect of high-energy ball milling conditions on microstructure and hydrogen desorption properties of magnesium hydride and single-walled carbon nanotubes"

The Authors present and discuss on a method for obtaining MgH2-5 wt% SWCNT composites, by ball milling under argon atmosphere in an AGO-2 planetary mill, carried out at various milling speeds, and the influence of the synthesis parameters of composites on the hydrogen desorption temperature.

The manuscript is well written, however some aspects need further and careful attention.

* Title: meaningful
* Keywords: meaningful 
* Abstract: not meaningful, please rephrase it and insist more on the novelty and importance of your work; avoid the use of speculative words (e.g. successfully, ...); use present tense (recommended).

1. Introduction

* this section is not sufficiently developed; the Authors need to insist more on the novelty and importance of their work with respect to literature (important publications are missing): further explain on your approach, and also consider providing further references to it; avoid redundant text; the last paragraph of the section needs to briefly present the main aspects of this work.


2. Experimental methods (2. Materials and methods)

* as a general remark, some of the experimental methods in this section need to be further discussed; however, there's no need to present well-known techniques (references will suffice); avoid redundant text; provide further references to better understand your approach.


3. Results and discussion 

* please start the section by describing the main aspects of your work - what do you seek and what is your plan in doing so (a few phrases will suffice);
* as a general overview / remark to this section: the Authors need to further discuss their results in a more correlated manner; provide further references; please further present and discuss in text all figures and tables, provide references where available; in some cases, the details / scale bars in the graphs / images are not clear, and/or they are not consistent (use similar magnifications / scale bars or further discuss on your choice);
* the last paragraph of section 3 must be rephrased, as it should include a more consistent conclusion of your work (insist more on the novelty of your work).


4. Conclusion (4. Summary)

* this section is meaningful, yet please rephrase it to emphasize more on the novelty and importance of your work; provide further data relevant to this study; do not use numbering / bullet points (recommended).

 

Minor aspects

* check the manuscript for typographical errors (spelling, punctuation, etc).
* avoid providing redundant data, superfluous text, or the repetitive use of speculative words or phrases, etc.


To conclude, the manuscript should be considered for publication only after careful and thorough revision.

Author Response

Dear Reviewer:

Please find attached for your kind review our manuscript after revision entitled “The effect of high-energy ball milling conditions on microstructure and hydrogen desorption properties of magnesium hydride and single-walled carbon nanotubes”.

We have changed the following points and marked it by color in paper:

1. In the research work, novelty was highlighted. We have analyzed a large number of articles and research papers, only a small part of the literature review is presented in the introduction. In our case, the novelty consists in the unambiguous determination of the influence of such parameters as the time and speed of milling on the hydrogen desorption properties of MgH₂–carbon nanotubes composites. The fact is that after analyzing the literature, we got an incomplete understanding of how these parameters can affect the presented properties. Some authors say that it takes tens of hours of milling to obtain a catalytic effect; other researchers indicate that positive results are achieved after several tens of minutes with comparable grinding speed parameters. There are also authors who argue that carbon nanomaterials have no catalytic effect at all. Therefore, we decided to conduct our own study in order to determine the influence of the listed parameters on the activation energy and the temperature of hydrogen desorption.
2. Most of the section "‎Introduction"‎ has been revised as well as "Summary" section.
3. We tried to rewrite some of the sentences throughout the article. We also tried to remove speculative words according to your recommendations.
4. Some sentences were removed and new ones were added, that are more relevant to the topic and objectives of the study. Numerous literature references were also given in the text (sections: introduction, experimental methods, results and discussion).
5. Section "‎Results and discussion"‎ now starts with few phrases – what we want to do. Slightly expanded description and discussion of the results obtained
6. The scales of the compared SEM images has been corrected.
7. Fixed most of grammar and typographical errors.

Look forward to your favorable consideration.

Most sincerely,

Viktor Kudiiarov, PhD.

National Research Tomsk Polytechnic University

[email protected]

89138700989

Round 2

Reviewer 1 Report

The author made necessary modifications and agreed to accept

Reviewer 2 Report

"The effect of high-energy ball milling conditions on microstructure and hydrogen desorption properties of magnesium hydride and single-walled carbon nanotubes"

The Authors correctly addressed most of the issues raised during the peer-review procedure. The manuscript is now improved and suitable for publication.