Three-Dimensional Graphene Aerogel Supported on Efficient Anode Electrocatalyst for Methanol Electrooxidation in Acid Media
Round 1
Reviewer 1 Report
1. Authors can improve the introduction part highlighying the use of methanol as fuel and issues with methanol such as metahnol crossover by citint appropriate refrences for ex:10.1016/j.cej.2014.01.030, 10.1039/C6RA23510G.
2. Calculation methods for electrochemical parameters suchas ECS, MA,SA should be given in experimental section.
3.catalyst ink composition and preparation method should be given
Author Response
Please find in attachment
Author Response File: 
Author Response.docx
Reviewer 2 Report
Reviewer’s comments
The manuscript titled “One-Pot Fabrication of a Three-Dimensional Graphene Aerogel Anodic Catalyst Support for Direct Methanol Fuel Cells” by Osman etal. Is well written. However, a major revision is suggested to address following comments.
1. Title seems quite general, need to rephrase according the application performed in this work.
2. Several ceramic materials such as NiO and its composite have also shown good activity with tolerance towards CO adsorption, but no literature of ceramic materials is includes. Following manuscripts are suggested to include in introduction to compare this material with ceramics.
i) An Electrochemical Investigation of Methanol Oxidation on Thin Films of Nickel Oxide and Its Composites with Zirconium and Yttrium Oxides
ii) Fabrication of metal (Cu and Cr) incorporated nickel oxide films for electrochemical oxidation of methanol
3. Page-04, 2.5, XRD is abbreviation of X-ray diffraction not sample, please correct.
4. P-4, 2.6, how electrochemical active surface area is calculated, please add details of calculations and formula in this section to improve readership.
5. Why author used acidic conditions for oxidation purpose, rather than basic. Justify it.
6. P-5 apparently no difference is noticed between Raman Spec. of PtRu/GA and GA. Why?
7. Fig. 3 labling of a-e not clear. Moreover, in HR-TEM lattice planes (fringes) are not visible, how did author draw the lines? Furthermore, in SAED lattice points are not highlighted and their comparison with xrd results should be added. In short, HR-TEM and SAED are not interpreted correctly.
8. P-7, Add formula and calculations for determination of specific activity to improve readership.
9. P-7, second paragrapgh, current produced by PtRu/ GA is about 3 times not 1.5 times as compared to PtRu/C. correct this
1- XPS should be added for materials before and after their use for catalytic activity.
1- GCMS of gas released should be added.
1- Impedance studies are missing.
Author Response
Please refer to attachment
Author Response File: Author Response.docx
Reviewer 3 Report
In this manuscript, the graphene aerogel was synthesized as a support for platinum nanoparticles, which is used for direct methanol fuel cells. Authors put forward hypotheses that the PtRu/GA catalyst enhanced the mass activity and specific activity compared to the commercial PtRu/C because the porous structure enhanced mass transport. In addition, the PtRu/GA improve the stability and the tolerance to CO poisoning.
(1) Do you have EDS mapping to show they are alloys? Do you have evidence that the atomic ratio of Pt to Ru is 1:1?
(2) Explain how did you get the numbers for the interlayer spacing from XRD.
(3) Figure 2(b), x axis for Raman spectrum is conventionally labeled as "Raman shift".
(4) Can you explain why PtRu/GA has more defects than GA?
(5) What's the difference between figure 4(b) and 4(c)? They seem to be identical.
Some editing needed:
For your title: you just tested the activity of the catalyst, and did not test the catalyst in an actual methanol fuel cells, so please change it to "methanol oxidation".
In the description of GA synthesis in figure 1, the graphene oxide was used instead of "graphene". Also, it is not appropriate to show the hydrothermal synthesis by drawing a beaker submerged into the water of a larger beaker.
Fix the labels and the caption of Fig 3.
The paragraph below figure2: should be "Figure 3" not "4". Figure "6", should be "5".
Fix the typo "ward" for "water".
Somewhere in the manuscript, can you give the reaction equations of your oxidation and reduction reactions?
Out of 33 references, you have 6 self citations, almost 20%. Please expand the spectrum of your references.
Author Response
Please refer to attachment
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Most of the queries are addressed and the manuscript is recommended for publication.
Author Response
Most of the queries are addressed and the manuscript is recommended for publication.
Reviewer 3 Report
The authors did some improvements on giving detailed description of the experimental procedures and discussions. Here are some issues that need to be further addressed:
(1) Improve the resolution of the electron microscopy images in figure 4. The scale bars are barely legible.
(2) The legend of figure 3(c) is labelled as "Pd".
(3) Line 231: Figure 5(c) is not the EDX spectrum.
(4) It is known that EDX is not a quantitative technique. Therefore, it is not a reliable evidence for the atomic ratio of the Pt-Ru alloy. A more quantitative technique, for instance, ICP-AES, can give the accurate atomic ratio of the electrocatalyst.
(5) Line 309: Change "equation (1)" to "equation (4)".
(6) Line 343: As you have described that "PtRu/C electrocatalyst has greater CO tolerance", you should change your claim that "PtRu/GA presents high tolerance to CO poisoning" in the abstract and in later discussions (line 406).
(7) Line 405: It says "The PtRu/GA nanocomposite catalyst shows a slower current decay than the other catalysts". I am not sure if I agree with this argument. PtRu/GA lost ~80% (55 out of 70 mA/mg) of the current density within the first 1000 seconds, while PtRu/C only lost ~40% (0.025 out of 0.065 mA/mg) of its original current density.
(8) Line 436: The acclaimed "lower onset potential" of the PtRu/GA does not agree with the onset potential values in table 1.
Author Response
Please refer to attachment
Author Response File: Author Response.docx
