Novel Synthesis of Nitrogen-Containing Bio-Phenol Resin and Its Molten Salt Activation of Porous Carbon for Supercapacitor Electrode
Round 1
Reviewer 1 Report
The authors presented interesting synthesis method of nitrogen-containing carbon. There is a lot of examples of phenol-formaldehyde condensation proces utilized in carbon synthesis [1], as well as of those modified with nitrogen-containing precursors [2-4].
In this work, except for phenol and formaldehyde, new precursors - bio-phenolic resin obtained from pyrolysed poplar sawdust and urea, were utilized as carbon or carbon/nitrogen sources, respectively. The examined carbon (one sample only), was modified with NaCl-KCl-KOH mixture to develop microporosity. The authors presented surface area and parameters related to the porosity of the sample, as well as electrochemical energy storage analysis. The sample exhibited moderate specific capacitance, but capacitance retention ratio was high.
The following mistakes should be corrected:
There are incorrectly numbered pages in this communication! Making this review I am using appropriate pagination! The Communication is probably too long. The work is written inaccurately, e.g. the last Chapter of the work is designated as 5.0, but a chapter 4.0 doesn’t exist at all.
page 1, line 7 The e-mail adress of the author: Xin Yan was doubled;
page 1, line 16 The name ‘poly formaldehyde’ should be exchanged for ‘paraformaldehyde’;
page 3, line 114 The authors examined the nitrogen content in bio-phenol resin, and it was sufficiently high. However, no information on the nitrogen content in the carbon material, both before and after activation with NaCl-KCl-KOH was provided. This information is mandatory;
page 4, line 129 I recommend change the title of the Chapter 3.4, because, e.g. surface area value is calculated using N2 adsorption isotherm. My suggestion of the new title is: ‘Surface area and porosity determination using N2 adsorption’;
page 4, line 131 The analysis of the N2 adsorption isotherm is inaccurate and insufficient. The isotherm shows the characteristic of the ‘typical isotherm‘. To which type of isotherm according to IUPAC classification this expression refers?
Instead of maximum an expression ‘plateau’ could be used. If the material exhibits ‘this’ type of isotherm, we cannot suspect any hysteresiss loop. This is typically microporous material.
page 4/5, lines 136-138 This sentence should be written once again. My suggestion is: Because of the fact, the activation with KOH produces a large numer of micropores, which improves the specific capacitance of the carbon [22], we used this method… . The obtained carbon reached the specific surface area and pore volume of 1401 m2/g and 0.61 cm3/g, respectively;
page 5, line 138 1. The name of the Y axis in Figure 4b should be corrected;
2. The authors didn’t mention according to which method the Pore Size Distribution, presented in Fig. 4b was calculated. It should be included;
page 5, lines 139-140 According to which method Vt, Smi, and Vmi (Table 1) were calculated? Moreover, the Table 1’ caption should be corrected;
page 6, lines 143-144 The caption of Figure 5c) should be changed;
page 6, lines 150 The shape of CV lines is no longer rectangular above cycling rate of 50 mV/s;
page 6, line 161-162 The existence…of ions. This is stylistycally incorrect sentence;
page 6, line 163-164 Since the ratio…satisfactory. This is stylistycally incorrect sentence;
page 6, line 169-170 It is a useful method…which method?
page 6, line 174 The low-frequency curve is definitely not near-perpendicular;
page 7, line 200 Instead of ‘Journal of Porous Materials 2018,6,1-9’ should be ‘Journal of Porous Materials 2018,25,1521-1529’.
page 8, line 239 ’26.’ is doubled.
I recommend major revision of the work and in my opinion English should be checked carefully. Practically, starting of the Chapter 3.4 the work should be written once again.
[1] C. Liang et al., JACS 128 (2006) 5316-5317.
[2] H. Chen et al., Electrochim. Acta 148 (2014)187–194.
[3] S. Liu et al., Micropor. and Mesopor. Mater. 259 (2018) 54-59.
[4] Z. Xin et al., J. of Por. Mater. 25 (2018) 521–1529.
Author Response
dear reviewers,
We would like to thank you for giving us a chance to resubmit the paper, and also thank you for giving us constructive suggestions which would help us both in English and in depth to improve the quality of the paper.The literature you listed will be helpful to my next work. The point to point responds to the comments can be found in the attachment.
Sincerely,
Tao Ai
Author Response File: 
Author Response.docx
Reviewer 2 Report
Authors reports the synthesis of nitrogen-containing bio-phenol resin and its application for supercapacitor. High specific capacitance as well as good cycling stability were achieved. There are some aspects should be addressed before publication as following:
1. Some papers with the similar approach have already been published. Therefore, the authors should clearly show highlights of work.
2. It is suggested that more analysis and discussion of Nyquist plot including the equivalent circuit should be added in the manuscript.
3. The authors should compare the electrochemical performance of author devices with other reported MSCs.
Author Response
dear reviewer,
We would like to thank you for giving us a chance to resubmit the paper, and also thank you for giving us constructive suggestions which would help us both in English and in depth to improve the quality of the paper. The point to point responds to the comments can be found in the attachment.
Sincerely,
Tao Ai
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors corrected most of the listed mistakes. However, the following errors were not corrected/appeared in this version:
The pages of the manuscript are still incorrectly numbered!
page 3, linev 122 Instead of ‘remain’should be ‘remains’,
page 4, line 137-138 The authors didn’t answer the question: ‘To which type of isotherm according to IUPAC classification this expression refers?’
page 4, line 139 What does the expression ‘adsorption platform’ mean?
page 5, line 146-147 1. The unit of the Y axis in Figure 4b should be corrected;
2. Was the PSD (in Fig. 4b) calculated by Horwath Kawazoe method?
3. The ‘word’ absorption’ in Fig. 4a should be exchanged for ‘adsorption’;
page 6, line 174 The phrase ‘mesoporous pores’ should be corrected;
page 7, line 176 The phrase ‘mesoporous pores’ should be corrected;
page 7, line 186 The part of the sentence should be crossed out: ‘The linear inclination of the low frequency region increases rapidly, and tends to be perpendicular to the Y axis, which means that the electrode tends to be charge-saturated.’
page 7, line 189 The authors added new results and it is profitable. However, the new figure mentioned in the text should be marked with an appropriate numer. Moreover, the reviewer didn’t find the numer of the figure added to the last page, (should be Fig. 6) and an appropriate figure’s caption should be added. Finally, the additional points from other publications, if added to the Ragone plot for comparison, should be obtained at the same current density and in the same environment.
page 7, line 202 The word ‘applied’ should be exchanged with a word ‘used’.
Comments for author File: Comments.docx
Author Response
dear reviewer,
Thank you very much for your detailed revision! It is very helpful to me!
The point to point responds to the comments are listed as following:
comments 1:
The pages of the manuscript are still incorrectly numbered!
Response:
Sorry! I have corrected the error.
comments 2:
Instead of ‘remain’ should be ‘remains’
Response:
I have corrected the error.
Comments 3:
To which type of isotherm according to IUPAC classification this expression refers?’
Response:
This expression refers to type Ⅰ isotherms.Type I isotherms characterize microporous adsorbents.
Comments 4:
What does the expression ‘adsorption platform’ mean?
Response:
I think that ‘adsorption platform’ mean saturated adsorption.The appearance of adsorption platform does not indicate that the pore distribution is mainly microporous, so I have deleted the sentence of ‘adsorption platform’.
Comments 5:
The unit of the Y axis in Figure 4b should be corrected.
Response:
I have corrected the error.
Comments 6:
Was the PSD (in Fig. 4b) calculated by Horwath Kawazoe method?
Response:
Sorry! It was not calculated by Horwath Kawazoe method, but by BJH method.
Comments 7:
The ‘word’ absorption’ in Fig. 4a should be exchanged for ‘adsorption’;
Response:
I have exchanged the word.
Comments 8:
Line 174, line 176, The phrase ‘mesoporous pores’ should be corrected.
Response:
All the errors were corrected.
Comments 9:
The part of the sentence should be crossed out: ‘The linear inclination of the low frequency region increases rapidly, and tends to be perpendicular to the Y axis, which means that the electrode tends to be charge-saturated.’
Response:
Thank you for your valuable advice. I have deleted the sentences.
Comments9:
The authors added new results and it is profitable. However, the new figure mentioned in the text should be marked with an appropriate numer. Moreover, the reviewer didn’t find the numer of the figure added to the last page, (should be Fig. 6) and an appropriate figure’s caption should be added. Finally, the additional points from other publications, if added to the Ragone plot for comparison, should be obtained at the same current density and in the same environment.
Response:
Thank you for your valuable advice. I have added a new Ragone plot for comparison at the same current density and in the same environment.
Comments10:
The word ‘applied’ should be exchanged with a word ‘used’.
Response:
Thank you for your valuable advice. I have exchanged the word.
Sincerely,
Tao Ai
Reviewer 2 Report
Authors responsed my concers. I recommend for the publication.
Author Response
Dear reviewer,
Thank you very much for your Professional advice！
sincerely
Tao Ai
