Improving the Activity of Fe/C/N ORR Electrocatalyst Using Double Ammonia Promoted CO₂ Laser Pyrolysis

Round 1

Reviewer 1 Report

In this manuscript, Perez and coworkers reported the CO2 laser pyrolysis synthesis method to prepare Fe/N/C ORR catalysts. The authors claimed that the developed catalysts showed better ORR performance compared to one of a single pyrolysis catalysts. They define R-parameter which was considered as key factors to improve the catalytic performance. The reviewer thinks that the Synthetic method looked quite interesting and the development of efficient electrocatalysts for ORR is of great importance. Therefore the reviewer would recommend accepting this manuscript if the following comments are fully addressed.

1. The main claim of this manuscript is that ORR activity can be controlled and improved via changing the catalyst preparation method. However, activity characterization is too poor. They only provided the simple cyclic voltammetry curves to compare activity. But the potential reader may want to know the products from the oxygen reduction reaction. Is it hydrogen peroxide or water? How can the authors be sure that the observed current increase is actually originated from the ORR, not from HER or non-faradaic current?

2. Also, the authors mentioned that ORR current is measured on the background-corrected cyclic voltammetry. The authors should provide details of how to process the raw data by showing CV data under argon.

3. The authors only displayed the SEM figures of DSCAT materials. What’s the difference between SSCat and DSCat in terms of electrochemical active surface area (ECSA)? It may give us some clues to explain the improved activity.

Author Response

"Please see the attachement"

Author Response File: Author Response.docx

Reviewer 2 Report

The present manuscript deals with a very interesting topic, i.e. the enhancement of the electroactivity of Fe/C/N towards the oxygen reduction reaction in aqueous media by using an innovative double ammonia promoted CO₂ laser pyrolysis. The manuscript may be published upon major revisions:

 

• please add some recent literature in the Introduction section about the electrocatalysis of ORR in aqueous media (for example, doi: 10.3390/nano8090643; 10.1016/j.jelechem.2017.05.035; 10.1002/anie.201706602);
• please check the correct way to report units in line 63 and in the following;
• please report in the Materials and Methods section the method used to determine the ORR onset shift;
• please be consistent in Table 2 with the way of representing values, since some data show comma, while others full stop. The same can be observed in labels of Figure 3;
• in order to better investigate the morphology, crystallinity and elements distribution inside the samples, HR-TEM alongside with EDX mapping and XRPD analyses should be performed;
• it should be better explaining which mass is used to determine the quantity reported in y-axes in Figure 6;
• please add a Table showing a comparison about ORR shift with literature data obtained in aqueous electrolyte;
• within the whole manuscript, lots of mistakes are present. Therefore, the paper should be entirely revised, focusing on the text formatting, punctuation and English language. For example: in the abstract check the unit in line 27, line 209 “energy” not “energies”, and so on.

Author Response

"Please see the attachment"

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

No further comments to the authors.

Reviewer 2 Report

The paper can be accepted.