Biomass-Based Oxygen Reduction Reaction Catalysts from the Perspective of Ecological Aesthetics—Duckweed Has More Advantages than Soybean
Round 1
Reviewer 1 Report
Using duckweed as carbon source to prepare the ORR catalyst isa good idea and can achieve the sustaible development goals. However, the authors should pay attention to the questions as followed,
(1) Ecological aesthetics ? aesthetics? It is the right exxpression in this ms?
(2) Professional expression, such as P2 L81: pH=7 ?
(3) The obtained carbon named as DWCs, may be consisted of QDs. The authors should try to disperse them under ultrasound and charactterize them and test their acitivty.
(4) As know to all, duckweed often grows in durty water and adsorb and metal ions in their body. Authors should characterize the DWCs using element analysis. Perhaps, the presented catalytic actiivty is resulted from the metal in the DWCs. Controll is necessary.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This manuscript reported two biomass based ORR catalysts from moldy soybean and duckweed, respectively. Based on previous understanding on the ORR process, the authors compared reactivity and stability of ORR between these two biomass based catalysts and commercial Pt/C. It is found that under appropriate preparation conditions, two biomass based catalysts have better reactivity and stability of ORR than commercial Pt/C. I suggest the acceptance of this manuscript after addressing the following issues.
1. In Figure 1, SEM and TEM images need to be clearly distinguished, and the micropores in the images are not obvious. The author should adjust the sharpness of the SEM and TEM images or annotate the images.
2. In Figure 2(a), the higher the peak strength at 2θ approaching 10°, the more micropores need to be further explained, and please cite relevant literature.
3. It is mentioned in the manuscript that half-wave potential (E1/2) is usually used to compare ORR activities. Please cite relevant literature.
4. In Figure 3 and Figure 6, the electrochemical active area of different working electrodes should be provided for LSV tests due to electrochemical active area greatly influence the current density of ORR.
5. The reference electrode mentioned in the manuscript is Hg/HgO. However, the reference electrode in Figure 3 and Figure 6 is reversible hydrogen electrode (RHE) The author should provide the conversion relationship between these two reference electrodes.
6. Some format issues should be improved. For example, the font in the figure should be uniform. The word in the table should be centered.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript describes the fabrication, characterization and electrochemical testing of biomass derived carbon materials as electrocatalyst for oxygen reduction reaction. Production of carbon materials from biomass waste has its own merits. However, the manuscript has a few shortfalls that make it unacceptable in current form. Firstly, the organization of the discussion and results is done to seemingly compare the carbon materials prepared from two biomasses, whose sample preparation, chemical composition, characteristics are quite different. To claim one biomass precursor is better than the another is not convincing. It is suggested that the authors focus on carbon material prepared from only one biomass and systematically investigate the effect of parameters, or compare the results with the carbon catalysts from similar biomass sources. Secondly, the result and experiment might not be repeatable as the chemical composition, source of the used biomass are unknown. Neither does the manuscript exhibit significant scientific interests to broad audience. Thus, this has largely limited to the contributions/impact of the manuscript. Thirdly, in terms of data presentation, the N2 adsorption isotherm and the pore diameter distribution data for the MSC samples are inconsistent. The author should provide complete chemical analysis of both carbon materials, especially for the metal elements, as they could boost the ORR activity as single atom in the N-doped carbon materials. Figure 3b, 6b can be removed as the loading of catalysts are not the same. The fitting results of the equivalent circuit in the Nyquist plots should be provided. Moreover, some of the arguments are not accurate, such as the peak in XRD or Raman spectra does not necessarily correlate with the amount of micropore in the samples. Lastly, the manuscript has to be proof-read by professional academic/editor to eliminate typo/grammatic errors.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
In this work the authors reported an integrated approach in which ecological aesthetics into development of oxygen reduction reaction (ORR) catalysts of H2/O2 fuel cells. They used Moldy soybean and duckweed as raw materials and are adopted to prepare biomass based ORR catalysts. Both of the raw materials have advantages in activity, stability, environmental protection and resource richness over the conventional expensive and scarce noble metal based catalysts. Therein, duckweed is more environmentally friendly and simpler in the preparation process, and better in catalytic performance, which is more in line with the ecological aesthetics.
After careful evaluation of this manuscript, the authors performed all the experiments with enough care and attention. They presented the data in an elaborate and well narrated manner.
Author Response
Thank you very much for your high evaluation of our work.
Round 2
Reviewer 2 Report
After revision, this manuscript has been significantly changed and can be published as it is.
Reviewer 3 Report
The comments have been addressed sufficiently and the manuscipt could be accepted.
