Interfacial Electron Transfer and Synergistic Effects on NiCo(CA)@M Microbars That Boost the Alkaline Oxygen Evolution Reaction

Round 1

Reviewer 1 Report

In this manuscript, NiCo(CA)@M composites were fabricated by a two-step solvothermal method for in situ growth of NiCo alloy nanoparticles on metal-organic skeletons, and the composites exhibited excellent OER properties. In the composite material, the introduction of nanoparticles is also equivalent to the introduction of new active sites, and at the same time, there is charge redistribution between the nickel-cobalt nanoparticles and the metal-organic backbone, which is beneficial to enhance the electrochemical activity of the material. On the one hand, the choice of in situ growth of Ni-Co nanoparticles on the metal-organic skeleton can reduce the agglomeration of nanoparticles, on the other hand, the strong interaction between the two materials helps to enhance the material stability. After careful reading, I think the manuscript can be accepted after addressing the following specific issues:

1.       In Figure 4 in the text, the unit of the scan rate should be mV/s, not mv/s. During the writing process, the expression of the relevant unit symbols should be confirmed to be correct. This type of problem needs to be checked and corrected throughout.

2.       When choosing the substrate materials, have you considered other substrate materials? Choose the iron metal organic skeleton of the spindle in the article, what are its advantages?

3.       The NiCo(CA)@M in the article has relatively excellent electrochemical properties. What is the main benefit of this excellent electrocatalytic activity and stability? In the electrochemical performance analysis section, appropriate supplementary instructions can be made.

Moderate editing of English language required.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

 

In this article, NiCo(CA) nanoparticles to form a NiCo(CA)@M composite were grown on MIL-88A in situ by a simple two-step solvent thermal method. The results show that NiCo(CA)@M composite has rich active sites, and the formation of the composite induces charge redistribution between NiCo(CA) and MIL-88A, effectively reducing the reaction energy barrier, while  growth in situ was conducive to the improvement of material stability. Generally speaking, the manuscript is well organized and the data are discussed reasonably. However, before it is accepted for publication, several problems need to be addressed.

1. Please check the grammar and format to keep the manuscript fluent and unified. There are some places in the expression is not smooth, logic is not clear, needs further inspection and modification.

2. The common way to use MOF as an electrocatalyst is to use it as a template or carbonization to produce a derivative catalyst, but in this paper, you chose the solvent thermal method to synthesize composite materials. Please explain it. What are the benefits of doing this?

3. In the second paragraph of introduction, that is, when introducing the background materials, can you add some examples to support some facts and further enrich the content?

Please check the grammar and format to keep the manuscript fluent and unified. There are some places in the expression is not smooth, logic is not clear, needs further inspection and modification

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

This manuscript is devoted to the preparation and testing of the composite electrocatalysts constructed using MIL-88 MOF as a framework. The data presented in the manuscript are interesting and can be valuable for material chemists and researchers working in the area of electrocatalysis. 

On the other hand, despite the wide range of methods engaged for the prepared material's characterization the real nature of active species remained unclear and substantial revision of the manuscript should be performed to provide more precise description of the materials. The more detailed comments are given below:

1) Authors named the metal particles precipitated from the DMF solution or deposited onto the surface of MIL-88 as NiCo(CA) (Ni(CA), Co(CA)). In some cases, they named this substance as "nickel-cobalt nanoparticles", in some cases it was referred to as an "organic matter". Finally, from the XPS data, it is clear that both ionic and metals states are observed for the Ni and Co in these materials. To make the things clearer, authors should give a thorough description of the nature of the NiCo(CA) and corresponding monometalic particles. Now it seems like authors have deposited something on the supporting MIL-88 material and measured its electrochemical characteristics without care for the in-depth studying of the prepared material. Summarizing, the prepared materials are interesting, but it should be properly described to avoid its characterization as a'black box'.

2)  Electrochemical oxydation of water was studied in alkiline solution while as it clear from the presented experimental data the prepared materials CoNi(CA) substance contain citric acid. How the authors have avoded the leaching of citric acid in alkaline media that should unavoidably lead to the destruction of the CoNi(CA) layer?

3) Page 5 line 197: " triethylamine was added to adjust the pH" It was not specified what is target pH value, moreover, it is strange to discuss the pH value when reaction was performed in DMF.

4) Page 6 line 209: "which is predicted from the structure and belongs to a 0D/2D interface. " It is not clear from which structure it was predicted?

5) Figure 2. Where the 2p1/2 bands for Ni2+ and Co2+ forms are located? Why they are not included in the fitting procedure?

6) In the electrochemical studies author did not mention the electrochemical oxidation of the citrate presented in the prepared materials itself. Where the waves from these processes should be located? 

There are a lot of mistakes and strange sentence in the manuscript. The text should be intensively proofreaded.

Here the not overwhelming list of found mistakes:

1)  "fumarate (C4H4O4,99%)" - should be "Fumaric acid" and the upper-lower cases should be checked (throughout of the manuscript)

2) "was added to a blue cap bottle" - It is principally to take a bottle with a blue cap?

3) (Line 115)"They were then stirred at 80℃ for 1 h." Who was stirred?

4) (Line 151) "the suspension was removed uniformly dropped " please check

5) "to generate iron fund organic frame" check the word

6) "was added to coordinate with the metal source" strange phrase, please, reformulate

7) (Line 196-200) Very long sentence, please, split it.

8) (Line 211) "the elements Ni and Co are uniformly distributed in the hierarchical structure of the MIL-88A shell surface"  What authors intended to communicate here?

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Authors have performed a great work to improve the manuscript. In my opinion now it can be published in the Processes journal.