Electrolessly Deposited Carbon-Supported CuNiSn Electrocatalysts for the Electrochemical Reduction of CO2
Round 1
Reviewer 1 Report
This manuscript used electroless deposition method to plate Cu, Ni, Sn onto Palladium modified carbon fibers. The authors found out that Cu/Ni/Sn trimetallic alloy with deposition time of 30 minutes has the best CO2RR performance compared to other deposition times. According to product analysis, the production of hydrogen was prohibited and C2-C3 products formed. Please see below for the comments and questions:
1. I would like to point out that while the catalysts are made of inexpensive metals, the process of using palladium to make these catalysts is not economic.
2. Can you explain why as the deposition time increased from 30 minutes to 45 minutes, the number of metal particles deposited on carbon fibers decreased?
3. It is known that EDX is not a quantitative technique. It is recommended that inductively coupled plasma atomic emission spectroscopy (or similar technique) should be used to quantify the composition of the catalysts.
4. For the LSV experiments of CuNiSn with different deposition time (figure 3), why did CuNiSn_15 in both CO2 and N2 and CuNiSn_45 in N2 reached steady current densities at more negative potentials? Also CuNiSn_45 seemed to have higher current density than that of CuNiSn_30 according to the LSV experiments, but why did CuNiSn_45 have smaller amount of metal particles compared to CuNiSn_30? What contributed to the current in the CuNiSn_45 sample?
5. The Faradic Efficiencies reported in table 2 do not add up to 100%. For CuNiSn, overall FE is below 100% and for all the other samples, the overall FEs are above 100%.
6. You should provide GC data for the gas product analysis.
7. To confirm the stability of the catalysts at applied potentials, you should provide SEM images of the metal particles after the electrochemistry tests.
8. Some word editing is required:
(1) The full name of the chemical "EDTH".
(2) In Section 3.3, More descriptions on how the carbon fabric substrate was made catalytically active using Pd polymer ink are needed.
(3) Line 31, citation format.
(4) Line 207, should be "%FE".
(5) Line 259, should be "-0.6"
(6) The section number of "Catalyst Characterization" is incorrect.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
1. Why did you choose the electroless deposition method to prepare the catalyst and what are its advantages?
2. The text in Figure 5 (b) exceeds the limit. Please draw this figure again.
3. There are two kinds of expressions in the text: "Fig" and "Fig." Please unify the whole text. Please also unify whether the abbreviation of "Figure" in the figure annotation is required.
4. In this paper, only SEM, XRD and EDS were used to characterize the catalyst, and LSV was used to characterize the electrochemical performance. Whether this is too little is not illustrative.
5. Only the effect of deposition time on catalyst performance was investigated, and several more factors could be considered.
Author Response
We are greatly thankful to the reviewers for their careful review and comments, which are very helpful in improving this work. We would like to reply to their comments one by one and indicate our actions made in the revision.
Reviewer 2
- Why did you choose the electroless deposition method to prepare the catalyst and what are its advantages?
Response: We thank the reviewer for the comments. This method does not require an external power source because the reductant acts as an electron donor to reduce the metal ions. Additionally, advantages are that the method require low material cost because the metal is deposited on only chosen portions and metal deposition can be controlled by deposition time. We mentioned advantages in the introduction (Line 69-75)
- The text in Figure 5 (b) exceeds the limit. Please draw this figure again.
Response: We thank the reviewer for the comments. We corrected it, please see Fig.5
- There are two kinds of expressions in the text: "Fig" and "Fig." Please unify the whole text. Please also unify whether the abbreviation of "Figure" in the figure annotation is required.
Response: We thank the reviewer for the comments. We used Figure instead of Fig.
- In this paper, only SEM, XRD and EDS were used to characterize the catalyst, and LSV was used to characterize the electrochemical performance. Whether this is too little is not illustrative.
Response: We thank the reviewer for the comments. The aim of the present study was to study a preliminary investigation of the feasibility of using trimetallic alloy electrocatalysts to convert CO2 to valuable chemicals. Additionally, ICP results is shown in Table 1 and Fig. 8 shows XRD patterns of fresh and spent CuNiSn/CS and SEM image of fresh, and spent CuNiSn/CS. We also discussed the result related to the figure as appeared in Line 257-263. For further investigation, TEM and XPS should be used to study surface structure.
- Only the effect of deposition time on catalyst performance was investigated, and several more factors could be considered.
Response: We thank the reviewer for the comments. Form original draft, we mentioned that “further improving the performance of the catalysts is an important but challenging task. To this aim, several effects need to be considered, including the electroless bath composition (CuSO4:NiSO4:SnSO4), the influence of electrolytes, and the applied potentials.” Line 251-254
Reviewer 3 Report
Authors reported trimetallic alloy electrocatalysts containing Cu, Ni, and Sn supported on a Pd-activated carbon fabric substrate were prepared via an electroless deposition method. Following revisions should be made before publication:
1) In Figure 6. reporting catalyst (CuNiSn/CS) current density is lesser than CuNi/CS. What is the reason behind it?
2) Typing error in the third row of electrocatalyst name in Table-2. and row number 207, probably is % FE.
3) According to my view, the stability (figure 7.) could be better. Thus, repeat the experiment and replace the data with it.
4) In introduction section following article based on transition metal compounds can be added wit integrity to insight the importance of TMC
doi.org/10.1016/j.est.2023.106713, doi.org/10.1016/j.compositesb.2022.110339, doi.org/10.1016/j.cej.2021.129312
5) Attaching the gas chromatography results is probably useful for better understanding to the readers, as the author mentioned the gaseous products were analyzed by gas chromatography.
6) Calculate the faradaic efficiency for the acetate and 1-butanol and added into Table 2.
7) Do the bassline corrections in the NMR spectrum and replace the data with it.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I appreciate the authors' kind response and the efforts to improve the manuscript. I believe the manuscript can be accepted.
Reviewer 2 Report
NO
