The Advanced Progress of MoS₂ and WS₂ for Multi-Catalytic Hydrogen Evolution Reaction Systems

Round 1

Reviewer 1 Report

In this manuscript the authors present a good synthesis of the literature dealing with the activity towards hydrogen evolution reaction of emerging non noble catalysts, MoS2 and WS2 and so on.

They analyze the strategies adopted to improve their efficiency.

I think that  data are nearly accurate but according to my opinion, they should be re-arranged in a proper way to be most appealing for researchers.

Tables are recommended in a review paper. The reader wants to know the overpotential, the stability, the tafel slope of each catalyst presented in the work, so the authors should report also the experimental data taken from the literature.

Carefully read the manuscript because I found some confusing sentences,

here some examples but 

LINES 10-14  However, the electrochemical catalytic hydrogen evolution performance of  TMDs with two-dimensional properties is limited by innate sparse catalytic active sites, poor electrical conductivity and weak electrical contact with the substrate, etc., and its intrinsic activity and overall activity of electrocatalytic hydrogen evoluti on  remain challenging to compete with the noble metal platinum. 

LINES 32-33 and reduce international conflicts and conflicts caused by the fossil energy crisis, thereby promoting harmonious global development, enhancing sustainability and reducing pollution  [1-3]

and so on

Author Response

Reply to review report #1 and revisions made accordingly:

1. For the comments “I think that data are nearly accurate but according to my opinion, they should be re-arranged in a proper way to be most appealing for researchers.” And “Tables are recommended in a review paper. The reader wants to know the overpotential, the stability, the Tafel slope of each catalyst presented in the work, so the authors should report also the experimental data taken from the literature.”

Response: Thanks for the comments and suggestions from the reviewer. We carefully organized two new tables in the paper to further appeal to researchers and provide a more intuitive manifestation of data.

Table 1 at page 12, line 424, aim to cite some case of catalysts modified by structural engineering and their performance in HER, besides providing an intuitive understanding of the different type of structural engineering. Table 2 at page 19, line 666, compared photocatalytic performance on MoS₂ compound with semiconductors. We are confident that those tables could attract the attention of researchers.

Table 1. Comparison of HER performance on different catalysts modified by structural engineering.

Catalyst	Engineering strategy	Electrolyte	η@10 mA cm–2 (mV)	Tafel slope (mV dec–1)	Ref.
Monolayer MoS2	Defect/strain	0.5 M H2SO4	170	60	[95]
Monolayer MoS2	Defect	0.5 M H2SO4	362.4	135	[96]
MoS2 thin-film	Defect	0.5 M H2SO4	350(η10.97)	105	[97]
MSORx	Doping	1 M KOH	63	43	[98]
MoS2/NiS2	Doping	1M KOH	62	50	[99]
Ru/np-MoS2	Strain/doping	1M KOH	30	31	[100]
F-MoS2	Strain	0.5 M H2SO4	-	59	[101]
1T′-MoS2	Phase	0.5 M H2SO4	65	100	[102]
Ni-1T-MoS2	Phase/doping	1M KOH	199	103	[103]

 

Table 2. Comparison of photocatalytic performance on MoS₂ compound with semiconductors

Combine with semiconductor	Light source	Reaction condition	Photocatalytic performance	Ref.
MoS2 with ZbIn2S4	300 W xenon lamp (> 420 nm)	0.25 M Na2SO3 and  0.35 M Na2S solution	~117 μmol h–1 g–1	[120]
MoS2 with Fe3O4	100 W halogen lamp	15% v/v triethanolamine solution	2480 μmol h–1 g–1	[121]
MoS2 with Cds	300 W xenon lamp (> 400 nm)	30 vol% lactic acid solution	29 mmol h–1 g–1	[122]
MoS2 with Cds	300 W xenon lamp (> 400 nm)	30 vol% lactic acid solution	31 mmol h–1 g–1	[123]
MoS2 with Cds	300 W xenon lamp (> 300 nm)	20 vol% lactic acid solution	1.695 mmol h–1 g–1	[124]
MoS2 with CdSe	300 W xenon lamp (> 400 nm)	0.1 M Na2SO3 and  0.1 M Na2S solution	890 μmol h–1 g–1	[125]
MoS2 with AgInZnS	300 W xenon lamp (> 420 nm)	10 vol% lactic acid solution	944 mmol h–1 g–1	[126]
MoS2 with TiO2	300 W xenon lamp	20 % methanol  solution	4300 μmol h–1 g–1	[127]
MoS2 with Cds	300 W xenon lamp (350-800 nm)	20 % methanol  solution	580 mmol h–1 g–1	[128]

 

2. For the comments “Carefully read the manuscript because I found some confusing sentences, here some examples but LINES 10-14 ‘However, the electrochemical catalytic hydrogen evolution performance of TMDs with two-dimensional properties is limited by innate sparse catalytic active sites, poor electrical conductivity and weak electrical contact with the substrate, etc., and its intrinsic activity and overall activity of electrocatalytic hydrogen evolution remain challenging to compete with the noble metal platinum.’ and LINES 32-33 ‘and reduce international conflicts and conflicts caused by the fossil energy crisis, thereby promoting harmonious global development, enhancing sustainability and reducing pollution [1-3].’ and so on.

Response: Thanks for the comments and suggestions from the reviewer. We sincerely apologize for our careless use of words and language organization. Carefully and thoroughly check of words and expression are implemented in our review paper; here are the elaborate changes, including those the reviewer illustrated and some other typical examples that need to be changed after our self-review. Besides, Changes in whole sentences or large paragraphs are highlighted in the text.

(1) Confusing sentences

“However, the electrochemical catalytic hydrogen evolution performance of TMDs with two-dimensional properties is limited by innate sparse catalytic active sites, poor electrical conductivity and weak electrical contact with the substrate, etc., and its intrinsic activity and overall activity of electrocatalytic hydrogen evolution remain challenging to compete with the noble metal platinum.”

And “and reduce international conflicts and conflicts caused by the fossil energy crisis, thereby promoting harmonious global development, enhancing sustainability and reducing pollution [1-3].”

Were corrected as “However, the electrochemical catalytic hydrogen evolution performance of TMDs with two-dimensional properties is limited by innate sparse catalytic active sites, poor electrical conductivity and weak electrical contact with the substrate. The intrinsic activity of TMDs for electrocatalytic and photocatalytic hydrogen evolution reaction (HER) remain challenging to compete with the noble metal platinum.”

And “It will not only address human daily needs but also enhance the energy security of all countries and reduce international conflicts caused by the fossil energy crisis.”

(2) Other typical examples that need to be changed.

Including changes at LINES 114-115, 84-85, 261-263, 413-414 and so on.

Reviewer 2 Report

Here are my comments on the manuscript titled “The advanced progress of MoS2 and WS2 for multi-catalytic hydrogen evolution reaction systems”.

Decision: Major Revision

1. The authors directly introduce structural engineering strategies in Section 2. The authors did not state any reason why they do so. It is too abrupt. The authors should provide transition sentences.

2. In Section 2.1, the authors discussed defects engineering. Any details about the concept and type (dot, line and plane) of defects, methodology to create defects, and potential mechanism of defects in increasing HER are lack. Similar to other Sections. I suggest the authors add subtitles such as concept, types and methodology.

3. The authors put too much attention in introducing one paper. For example, when introducing doping engineering, the authors used four paragraph to introduce one paper. Since this is a review article, the authors should summarize few typical papers and extract useful information from them.

4. In Section 3, the authors introduced co-catalyst strategy to increase HER performance and introduced four subsections including TiO2, CdS, TiO2 and CdS, and ZnIn2S4. Actually, all these compounds are similar. There is no need to separate them into different subsections.

5. Please also add few tables to summarize these strategies.

Author Response

Reply to review report #2 and revisions made accordingly:

1. The authors directly introduce structural engineering strategies in Section 2. The authors did not state any reason why they do so. It is too abrupt. The authors should provide transition sentences.

Response: Thanks for the comments and suggestions from the reviewer. A paragraph was added between heading 1 and its subheading acts as a transition paragraph to create a natural transition between the two parts details as follows: “One promising approach to improve electrocatalysis and photocatalysis is to increase the density of active sites, activate the intrinsic activity of the original inert site and adjust the electronic structure of the catalyst by structural engineering. To achieve highly efficient and economical electrocatalysis and photocatalysis, researchers dedicated to fine-tuning the structure of catalysts by defects engineering, doping engineering, phase engineering, and strain engineering.”

2. In Section 2.1, the authors discussed defects engineering. Any details about the concept and type (dot, line and plane) of defects, methodology to create defects, and potential mechanism of defects in increasing HER are lack. Similar to other Sections. I suggest the authors add subtitles such as concept, types and methodology.

Response: Thanks for the comments and suggestions from the reviewer. We realized we really needed to add some concepts, methodology and mechanism into paper. We added a new paragraph, and insert many new sentences with re-arranged graphs into the original paragraph, to elaborate concept and type of defects, methodology to create defects and mechanism of defects in increasing HER. At LINES 77-85 “Defect engineering shows tremendous significance in modulating the electronic properties of catalysts, bringing about surprising physical and chemical properties optimization to improve the intrinsic bottleneck, therefore, boosting the HER performance. Presently, considerable efforts have been implemented to induce point defect (0-dimensional defect), line defect (1-dimensional defects), surface defect (2-dimensional defect), and body defect(3-dimensional defect) into the inert plane and bulk to activate intrinsic potential activity [47-54].To achieve efficiency and a low-cost approach to forming defects that boost HER performance, methods including chemical and physical etch, ball milling, interlayer regulation, and finely tuned synthesis steps were carried out [47-51].” Besides, we increase the proportion of mechanism in the paper and introduce more theoretical calculation.

3. The authors put too much attention in introducing one paper. For example, when introducing doping engineering, the authors used four paragraph to introduce one paper. Since this is a review article, the authors should summarize few typical papers and extract useful information from them.

Response: Thanks for the comments and suggestions from the reviewer. We put some adjustments into the doping engineering part to disperse attention on one article and, afterward, summarize a few typical papers instead. Figure 5 cited from Ref.77, illustrates the formation of Ni-1Tʹ-MoS₂ by Ni doping. Figure 6 cited from Ref.82, introduced S-O-MoS₂ catalyst.

4. In Section 3, the authors introduced co-catalyst strategy to increase HER performance and introduced four subsections including TiO2, CdS, TiO2 and CdS, and ZnIn2S4. Actually, all these compounds are similar. There is no need to separate them into different subsections.

Response: Thanks for the comments and suggestions from the reviewer. Dividing each compound into different subsections is really tedious to describe, they are all combined with MoS₂, we decided to cancel the subdivision in this section and combine them into a single section.

5.Please also add few tables to summarize these strategies.

Response: Thanks for the comments and suggestions from the reviewer. We carefully organized two new tables in the paper to further appeal to researchers and provide a more intuitive manifestation of data.

Table 1 at page 12, line 424, aim to cite some case of catalysts modified by structural engineering and their performance in HER, besides providing an intuitive understanding of the different type of structural engineering. Table 2 at page 19, line 666, compared photocatalytic performance on MoS2 compound with semiconductors. We are confident that those tables could attract the attention of researchers.

Table 1. Comparison of HER performance on different catalysts modified by structural engineering.

Catalyst	Engineering strategy	Electrolyte	η@10 mA cm–2 (mV)	Tafel slope (mV dec–1)	Ref.
Monolayer MoS2	Defect/strain	0.5 M H2SO4	170	60	[95]
Monolayer MoS2	Defect	0.5 M H2SO4	362.4	135	[96]
MoS2 thin-film	Defect	0.5 M H2SO4	350(η10.97)	105	[97]
MSORx	Doping	1 M KOH	63	43	[98]
MoS2/NiS2	Doping	1M KOH	62	50	[99]
Ru/np-MoS2	Strain/doping	1M KOH	30	31	[100]
F-MoS2	Strain	0.5 M H2SO4	-	59	[101]
1T′-MoS2	Phase	0.5 M H2SO4	65	100	[102]
Ni-1T-MoS2	Phase/doping	1M KOH	199	103	[103]

 

Table 2. Comparison of photocatalytic performance on MoS₂ compound with semiconductors

Combine with semiconductor	Light source	Reaction condition	Photocatalytic performance	Ref.
MoS2 with ZbIn2S4	300 W xenon lamp (> 420 nm)	0.25 M Na2SO3 and  0.35 M Na2S solution	~117 μmol h–1 g–1	[120]
MoS2 with Fe3O4	100 W halogen lamp	15% v/v triethanolamine solution	2480 μmol h–1 g–1	[121]
MoS2 with Cds	300 W xenon lamp (> 400 nm)	30 vol% lactic acid solution	29 mmol h–1 g–1	[122]
MoS2 with Cds	300 W xenon lamp (> 400 nm)	30 vol% lactic acid solution	31 mmol h–1 g–1	[123]
MoS2 with Cds	300 W xenon lamp (> 300 nm)	20 vol% lactic acid solution	1.695 mmol h–1 g–1	[124]
MoS2 with CdSe	300 W xenon lamp (> 400 nm)	0.1 M Na2SO3 and  0.1 M Na2S solution	890 μmol h–1 g–1	[125]
MoS2 with AgInZnS	300 W xenon lamp (> 420 nm)	10 vol% lactic acid solution	944 mmol h–1 g–1	[126]
MoS2 with TiO2	300 W xenon lamp	20 % methanol  solution	4300 μmol h–1 g–1	[127]
MoS2 with Cds	300 W xenon lamp (350-800 nm)	20 % methanol  solution	580 mmol h–1 g–1	[128]

 

Round 2

Reviewer 1 Report

The authors have revised the manuscript according to my suggestions. I think the paper Is now acceptable in the presente form. Thank you for tour kind responses

In my opinion the english language quality Is good

Reviewer 2 Report

The authors have well solved my concerns. I suggested accepting it for publication.