Nickel Foam-Supported Hierarchical NiCo₂S₄ Nanostructures as Efficient Electrocatalysts for the Methanol Oxidation Reaction

Round 1

Reviewer 1 Report

1. In Figure 9. Nyquist plots of the NiCo2S4/Ni foam electrode...., what is the electrode area?

2. In Figure 7. (a) CV curves of the NiCo2S4/Ni foam electrode..., what is the reaction for redox peak in CV of only KOH?

3. Please indicate the rod-like NiCo2S4 and thin nanoribborn shell in Figure 3d.

4. The authors have a similar investigation on the reference #19 (https://doi.org/10.1016/j.ijhydene.2021.06.226). Please provide the significant contribution of the current work.

5. In Figure 5 of a Ni 2p XPS spectrum, the spin-orbit doublets at 856.5 eV (Ni 2p3/2)  and 874.4 eV (Ni 2p1/2) correspond to the Ni2+/Ni3+ oxidation states. Is this the as-synthesized sample or spent material? 

can be improved, but ok

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors reported hierarchical NiCo₂S₄ nanostructures on a Ni foam support using a two-step hydrothermal process and tested their performance in the methanol oxidation reaction (MOR). However, certain discrepancies in the measurements need to be addressed before accepting the article. The major comments are outlined below:

1.       No commercial catalysts were reported in this study for comparison and validation of the electrocatalytic data. The authors should include suitable commercial catalysts to establish a comparative analysis and validate their findings.

2.       The use of Ag/AgCl as the reference electrode in this study is not appropriate for alkaline 1.0 M KOH solution. The authors should employ Hg/HgO as the reference electrode for alkaline electrocatalytic measurements.

3.       The potential range for the MOR is limited (Figure 7a, c), resulting in MOR curves that resemble the oxygen evolution reaction. The authors should conduct the MOR analysis over the full range of 0.05-1.00 V vs. RHE. They can refer to the following study (https://doi.org/10.1039/C9TA07066D) for guidance on electrocatalytic measurements.

Need to check for errors and Typos

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Can be accepted in current form.