The Effect of Corn Stover Carbon-Based Bimetallic Catalysts on the Depolarization Electrolysis Reaction of Sulfur Dioxide for Hydrogen Production

Comments 1: The reviewer recommends that the editors of the scientific journal Catalysts publish the manuscript of the article after a small editorial revision. There is an error in the cathode reaction 5, +2e- should be added to 2H⁺ (lines 52-53). The manuscript of the article is written on a relevant topic, contains new experimental data, and is designed according to the editorial rules.

Response 1: Thank reviewer for pointing this out. This problem has been modified in the manuscript (lines 52-53).

This paper prepared biomass-based carbon materials from corn stover through high-temperature pyrolysis technology and loaded platinum-chromium bimetal on them to act as an anode catalyst in the sulfur dioxide depolarization electrolysis (SDE) reaction for the production of hydrogen. As cellulose, holocellulose, lignin were obtained through different processes and their influences on the catalytic performance had been able to be studied and compared, which should be interesting to researchers in this related field. However, the following issues should be addressed by the authors:

Comments 1: In the title the words "for hydrogen production" should be added to make the background of this paper more clear.

Response 1: As the Reviewer's good advice. After our in-depth discussion, we decided to add the words "for hydrogen production" in the title.

Comments 2: Some SEM images should be provided for the materials in study.

Response 2: Thanks for the reviewer's suggestion, we have submitted the SEM images of carbon materials mentioned in the manuscript in the supplementary file.

Comments 3: In the text for Fig. 7 it was stated that "the Pt-Cr/BPC-30-700-2 catalyst demonstrates superior stability", while in Fig. 9 it can be seen that the current for Pt-Cr/BPC-30-700-2 decreases most seriously with increasing time. How to explain this inconsistence?

Response 3: Thanks for the reviewer's questions. We would like to make the following explanations for the questions:

The higher the peak voltage of metal oxidation peak, the lower the chemisorption rate of oxygen on the catalyst surface, the more difficult the catalyst particles are to be oxidized, and the higher the stability of the catalyst. From the perspective of CV characterization, we can conclude that Pt-Cr/BPC-30-700-2 catalyst exhibits excellent stability. However, the comprehensive performance of the catalyst also needs to be reflected in the application of SDE electrolytic reaction. The polarization curve of SDE electrolytic reaction (Fig. 8) is the most important criterion for evaluating catalyst performance (which corresponds to the data in Fig. 9). (https://doi.org/10.1016/j.ijhydene.2014.02.128)

According to the reviewer's question, we decided to add in part 2.3.2 of the manuscript: The polarization curve of SDE electrolytic reaction is the most important criterion for evaluating catalyst performance (lines 242-244).

Carbon support material preparation is the subject of a number of publications in the past. The present one adds to this knowledge domain. The authors have employed several characterization techniques and all of the are appropriate

However, there could be some comparison with the literature carbon materials

Comments 1: As stated above a comparison could have been made

Response 1: Thanks for the reviewer's suggestion. The manuscript we submitted mainly introduces corn stover carbon-based bimetallic catalysts and discusses the application of cellulose and lignin as biomass carbon materials in the introduction. Regarding the reviewer's suggestion, we provide the following supplement.

Biomass pyrolysis for carbon production is a well-established process. Matthew W. Smith et al. studied the effect of pyrolysis temperature on the morphology, bulk, and surface chemistry of cellulose, xylan, and lignin chars, yielding characterization data that similar with our results.(https://doi.org/10.1016/j.biombioe.2017.05.015) Li et al. utilized cornstalk (entire plant), rind, and pith as precursors for the synthesis of hierarchical porous carbons. These carbons were also used in electrochemical tests, and the results showed that they have excellent capacitance and energy density, which proves the expansion of corn stalk applications in the field of electrochemistry (https://doi.org/10.1039/C9TA07864A).Due to the length of the manuscript, we do not intend to include the above content in the manuscript.

Comments 2: spectral data expecially IR and Raman need more discussion

Response 2: As the Reviewer's good advice. We decided to add the following additions to the IR and Raman data discussion to the manuscript:

IR: In addition to the above, it can be seen in Fig. 3 that cellulose-based porous carbon and holocellulose-based porous carbons have similar structures, while lignin peaks more stronger than cellulose and holocellulose-based porous carbons at 1620-1120 cm^-1 due to its high aromatalization and cyclization.(lines 173-176) (https://doi.org/10.1016/j.joei.2023.101177)

Raman: For highly disordered carbon materials, ID/IG can be regarded as the relative concentration ratio of large and small aromatic rings (G peak represents small aromatic ring system, D peak represents aromatic cluster structures with more than 6 rings). Notably, lignin-based porous carbon demonstrates the highest degree of graphitization, this may be related with the aromatic structure of lignin and imply its relative conductivity. (lines 218-223)

(https://doi.org/10.1016/j.energy.2024.134320) (https://doi.org/10.1007/s42114-024-00850-5)