Review Reports - Tuning the Electronic Structures of Mo-Based Sulfides/Selenides with Biomass-Derived Carbon for Hydrogen Evolution Reaction and Sodium-Ion Batteries

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This review is well organized and sounding. In my opinion can be published in its present form.

The review entitled “uning the Electronic Structure of Mo-Based Sulfides/Selenides with Biomass-Derived Carbon for Hydrogen Evolution Reaction and Sodium-Ion Batteries” discusses the limitations of MoS₂/MoSe₂ electrode materials in hydrogen evolution reactions (HER) and sodium-ion batteries (SIBs) applications, introducing biomass-derived carbon (BMC) as a natural support for loading MoS₂/MoSe2 for energy storage and conversion and for catalytic reactions. For this latter application, the authors underlined that carbon catalysts based on biomass have important performance. In addition, this review lists the sources and methods to obtain BMC, and suggests approaches for incorporating BMC with MoS₂/MoSe₂ whose composites show improved performances. The review also analyses some future perspective and challenges for the application of BMC/MoS₂ and BMC/MoSe₂ materials. 18/100 references belong to Yang, J., author of the present review, thus demonstrating that the authors have already produced in this relevant field.

Tables and figures are appropriate. Comments on the Quality of English Language

The language is fine

Author Response

For review article

Response to Reviewer 1 Comments
1. Summary
Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.
2. Questions for General Evaluation	Reviewer’s Evaluation	Response and Revisions
Is the work a significant contribution to the field?
Is the work well organized and comprehensively described?
Is the work scientifically sound and not misleading?
Are there appropriate and adequate references to related and previous work?
Is the English used correct and readable?
3. Point-by-point response to Comments and Suggestions for Authors
Comments 1: This review is well organized and sounding. In my opinion can be published in its present form. The review entitled “Tuning the Electronic Structure of Mo-Based Sulfides/Selenides with Biomass-Derived Carbon for Hydrogen Evolution Reaction and Sodium-Ion Batteries” discusses the limitations of MoS₂/MoSe₂ electrode materials in hydrogen evolution reactions (HER) and sodium-ion batteries (SIBs) applications, introducing biomass-derived carbon (BMC) as a natural support for loading MoS₂/MoSe2 for energy storage and conversion and for catalytic reactions. For this latter application, the authors underlined that carbon catalysts based on biomass have important performance. In addition, this review lists the sources and methods to obtain BMC, and suggests approaches for incorporating BMC with MoS₂/MoSe₂ whose composites show improved performances. The review also analyses some future perspective and challenges for the application of BMC/MoS₂ and BMC/MoSe₂ materials. 18/100 references belong to Yang, J., author of the present review, thus demonstrating that the authors have already produced in this relevant field. Tables and figures are appropriate.
Response 1: We sincerely appreciate the reviewer’s high praise and recognition of our work. Our research group has been dedicated to the structural regulation of transition metal selenides and breakthroughs in their electrochemical performance, with several research and review papers already published. Moving forward, we will continue to tackle challenges in the preparation and application of these materials. This viewpoint is planned to highlight the fundamentals relevant to the topic, including the electronic modulation and structural engineering of Mo-based sulfides/selenides, as a complement to the reviews on SIBs and HER that have recently been published. Finally, we offer our opinion on the challenges and issues that may arise in the future, aiming to advance the application prospects of BMC/MoS₂ and BMC/MoSe₂ materials.


4. Response to Comments on the Quality of English Language
Point 1: The language is fine.
Response 1: We greatly appreciate your expert opinions on our manuscript. Your insightful opinions can help improve the quality of our article.

Reviewer 2 Report

Comments and Suggestions for Authors

In this manuscript, the author tuning the electronic structure of Mo-based sulfides/selenides with biomass-derived carbon for hydrogen evolution reaction and sodium-ion batteries. The manuscript should be accepted after addressing the following issues;

1) In the abstract, the authors should add more information related to the main findings and aspects, which studied in the review article.

2) In each section, the authors should add a table to improve the understanding and worth of the manuscript.

3) The authors should add a complete section of the synthesis and characterization of 2D and TMDs materials.

4) There are new materials such as MXene and MOF, the authors also added details related to the Mo-based composites with these materials.

5) The authors also add more information related to the mechanism of SIB and HER device; how this composite improves the performance supporting some chemical reactions etc.

6) In Figure 4, the authors studied the heterostructure-type materials in SIB and HER devices. The Interface quality affects the efficiency of SIB and HER devices.

7) Most of the references look old, the authors should modify the references and add references from the last three years

8) There are many similar works reported in the previous literature, the authors should emphasize the novelty and better performance as compared to the previous work.

9) Some figure quality is low, the authors should improve it.

10) The authors should improve the language of the manuscript carefully.

Comments on the Quality of English Language

The authors should improve the language of the manuscript carefully.

Author Response

For review article

Response to Reviewer 2 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Is the work a significant contribution to the field?

Is the work well organized and comprehensively described?

Is the work scientifically sound and not misleading?

Are there appropriate and adequate references to related and previous work?

Is the English used correct and readable?

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: In this manuscript, the author tuning the electronic structure of Mo-based sulfides/selenides with biomass-derived carbon for hydrogen evolution reaction and sodium-ion batteries. The manuscript should be accepted after addressing the following issues;

In the abstract, the authors should add more information related to the main findings and aspects, which studied in the review article.

Response 1: Thanks for the comment. We added the main findings and aspects in the abstract. The specific changes are as follows: This review addresses the scientific challenges related to the development of electrode materials for HER and SIBs in electrochemical energy storage and conversion. It delves into the recent focus on the two-dimensional transition metal chalcogenides, particularly MoS₂ and MoSe₂, and the difficulties encountered in modulating their electronic structures when applied to HER and SIBs. The review proposes the use of eco-friendly and widely sourced biomass-derived carbon (BMC) as a supporting matrix, combining with MoS₂ and MoSe₂ to regulate their structure and enhance their electrocatalytic activity and sodium storage performance. Additionally, it highlights the existing challenges faced by these BMC/MoS₂ and BMC/MoSe₂ composites and offers insights into future developments.

Comments 2: In each section, the authors should add a table to improve the understanding and worth of the manuscript.

Response 2: To facilitate organization and summarization, we have compiled tables of the literature on BMC/MoS₂ and BMC/MoSe₂ used for HER and SIBs, in accordance with the reviewers' suggestions.

Table 1. Comparison of various BMC/MoS₂ or BMC/MoSe₂-based nanocomposites for HER.

Material	Overpotential (in 10 mA cm⁻²)	Electrolyte	Stability(efficiency)	Refs.
MoS₂@NSC₃	209 mV	0.5 M H₂SO₄	15 h	[100]
Co-MoS₂-0.67-SCBC-0.2	62 mV	0.5 M H₂SO₄	12 h (90%~95%)	[99]
MoS₂@NiOOH@C-MC	250 mV	1 M KOH	48 h	[104]
Ru-MoSe₂/CMT	70 mV	1 M KOH	20 h	[119]
BCDs-MoS₂	115 mV	0.5 M H₂SO₄	20 h	[89]
DAC/MoS₂		0.5 M H₂SO₄		[91]
AC/MoS₂-F	136 mV	0.5 M H₂SO₄	24 h	[92]
MoS₂@Pt/YC	118 mV	0.5 M H₂SO₄	24 h	[90]
Co@NCNT/CW	263 mV (500 mA cm⁻²)	1M KOH	100 h	[122]

Table 2. Comparison of various BMC/MoS₂ or BMC/MoSe₂-based nanocomposites for SIBs.

Material	Current density (A g⁻¹)	Capacity (mAh g⁻¹)		Capacity retention @ cycle number	Refs.
MoS₂/TSFC	0.1		243	64% @ 500 cycles	[108]
MoS₂@BHCF	2		227	223 mAh g⁻¹ was maintained after 100 cycles at 0.05 A g⁻¹	[106]
MoSe₂/BC/CNTs	5		405	83% @ 250 cycles	[120]
MoSe₂/NP-C-2	0.5		215		[121]
GC@MoS₂@CC	0.1		589	69.7% from 100 to 200 cycles	[109]
MoS₂@AMCRs	1		366	83% @ 300 cycles,	[107]

Comments 3: The authors should add a complete section of the synthesis and characterization of 2D and TMDs materials.

Response 3: Agree. We have accordingly revised to emphasize this point. The main methods for synthesizing two-dimensional TMD[30-32] can be summarized as follows: 1) Chemical Vapor Deposition (CVD): A widely used technique where gaseous precursors react on a substrate to form high-quality, large-area TMD thin films such as MoS₂ and MoSe₂. The process allows for precise control over thickness and crystallinity. 2) Liquid-Phase Exfoliation: This method involves exfoliating bulk TMD crystals into monolayers or few-layer nanosheets in a solvent through sonication or chemical means. It is scalable and cost-effective, though it often yields less crystalline products. 3) Hydrothermal/Solvothermal Synthesis: TMDs are synthesized by reacting metal precursors with chalcogen sources in a high-pressure, high-temperature aqueous or organic solvent environment. This method offers control over morphology and phase, producing nanostructures like nanosheets or nanospheres. 4) Electrochemical Exfoliation: By applying an electric potential to bulk TMD materials in an electrolyte solution, layered TMDs can be exfoliated into ultrathin sheets. This method is efficient and produces high-quality exfoliated layers. 5) Molecular Beam Epitaxy (MBE): This technique involves the deposition of TMDs onto a substrate under ultra-high vacuum using atomic or molecular beams of the constituent elements. It yields high-purity and high-quality films but is more costly and complex. 6) Sulfurization/Selenization of Metal Films: Metal films (e.g., Mo or W) are first deposited on a substrate and then reacted with sulfur or selenium vapors at high temperatures to form TMD layers. This approach offers good control over the material composition and layer thickness. Each of these methods varies in scalability, cost, and the quality of the resulting TMDs, which affects their suitability for different applications such as energy storage and catalysis.

The synthesis methods for MoS₂ or MoSe₂, two prominent two-dimensional TMD, usually use the hydrothermal/solvothermal synthesis with metal precursors (e.g., ammonium molybdate) mixed with sulfur or selenium sources (e.g., thiourea or Se powder) in a solvent. This allows for morphology control, producing various nanostructures such as nanosheets, nanospheres, or flower-like structures. In addition, bulk MoS₂ or MoSe₂ can be exfoliated into monolayer or few-layer nanosheets in a solvent using sonication or chemical methods[40].

Comments 4: There are new materials such as MXene and MOF, the authors also added details related to the Mo-based composites with these materials.

Response 4: Thanks for the suggestion. We have added the description of MXene and MOF with MoS₂/MoSe₂ for HER and SIBs.

Recently, MXenes are 2D transition metal carbides or nitrides, known for their high conductivity, mechanical strength, and hydrophilicity. These characteristics make them ideal electrode for electrochemical reactions, including HER and SIBs[74, 75]. For instance, the layered structure of MXenes facilitates fast ion/electron transfer, leading to efficient hydrogen production. Surface modification, such as functionalization with -OH or -F groups, can enhance their catalytic activity. MXene-based composites with TMDs (MoS₂, MoSe₂) have gained attention[76, 77]. These combinations leverage the high conductivity of MXenes with the catalytic or sodium-ion storage capabilities of MXene-MoS₂/MoSe₂ composites. MXene-MoS₂/Se₂ composites can offer more active sites, better ion/electron transfer, and improved stability, leading to enhanced HER performance[78]. For SIBs, these composites can enhance the storage capacity and cycling stability of SIBs by providing better ion diffusion pathways and structural robustness[79]. On the other hand, metal-oganic fameworks (MOFs) are known for their large surface areas and tunable pore structures. These features enhance mass transfer and active site exposure, making MOFs promising candidates in HER catalysis and SIBs[80, 81]. By combining MOFs and MoS₂/MoSe₂, the composites exhibit synergistic effects. The MOF’s large surface area increases the exposure of active sites on MoS₂/MoSe₂, while the conductive framework supports fast electron transfer[82]. This enhances the overall HER efficiency and reaction kinetics in SIBs. The integration with MOFs mitigates these issues by providing a flexible framework that buffers volume changes during Na⁺ insertion/extraction, thus enhancing the cycling stability[83].

Comments 5: The authors also add more information related to the mechanism of SIB and HER device; how this composite improves the performance supporting some chemical reactions etc.

Response 5: Thanks for the comment. We have added the information of BMC-MoS₂/MoSe₂ composite for the improved performance in HER and SIBs. In fact, all examples in the article revolve around the enhancement of catalytic and sodium storage performance by the BMC-MoS₂/MoSe₂ composite. The numerous comparisons in the figures between the BMC-MoS₂/MoSe₂ composite and pure MoS₂ or MoSe₂ clearly demonstrate this point. For instance, the LSV curve in Figure 3 explains well how the introduction of BMC promotes the electrocatalytic activity of MoS₂. We believe that BMC contributes to improving the distribution of catalytic active sites in MoS₂ and facilitates ion transport. Furthermore, Figure 6 shows that the introduction of BMC significantly enhances the cycling stability and mass transfer kinetics of MoS₂ in SIBs. Alternatively, at the end of all the examples, we also provided a summary and conclusion as required.

The biomass carbon-MoS₂/MoSe₂ composite likely enhances the performance of SIBs and HER devices in following ways: Enhanced Electrical Conductivity: Biomass-derived carbon usually has a porous structure and high surface area, which can provide excellent electrical conductivity. This helps in the efficient transport of electrons during the chemical reactions in both SIB and HER processes. 2) Active Sites for Catalytic Reactions: MoS₂ and MoSe₂ are well-known for their catalytic properties, particularly in HER applications. The combination with biomass carbon could create more exposed active sites for the reactions, enhancing the catalytic efficiency. 3) Ion Transport and Storage: In SIBs, the composite might facilitate better ion transport and storage due to the layered structure of MoS₂/MoSe₂. The carbon material could act as a flexible matrix, accommodating volume changes during ion intercalation and deintercalation, improving the structural stability of the electrode. 4) Synergistic Effects: The interaction between the carbon, MoS₂, and MoSe₂ can lead to a synergistic effect, where the combined properties of these materials outperform what each material could do individually. For example, the carbon matrix could prevent the aggregation of MoS₂/MoSe₂ layers, maintaining their high surface area and activity throughout the battery's or HER device’s lifetime.

Comments 6: In Figure 4, the authors studied the heterostructure-type materials in SIB and HER devices. The Interface quality affects the efficiency of SIB and HER devices.

Response 6: Thanks for the comment. We have expanded the relevant reports on Mo-based electrode material heterostructures and their effects on HER and SIBs performance, as well as the underlying internal mechanisms in the revised manuscript.

It can be seen the interface quality of MoS₂ plays a crucial role in the efficiency of HER devices. Many reports have enhanced the HER performance of MoS₂ by constructing highly heterojunctions, such as CoS₂/MoS₂[101], MoS₂/Ti₃C₂[102], multiple metal single-atoms/MoS₂[103], and so on. A high-quality interface ensures minimal resistance and smooth charge transfer. Furthermore, ensuring good crystallinity and clean interfaces maximizes the number of exposed active sites.

In addition, stable interfaces prevent unwanted reactions that can form solid-electrolyte interphase (SEI) layers or other degradation products. A high-quality interface minimizes side reactions and prolongs battery life. Moreover, during the insertion and extraction of sodium ions, MoS₂ undergoes significant volume changes. A well-designed interface can accommodate the expansion and contraction without causing structural damage, improving cycling stability.

Comments 7: Most of the references look old, the authors should modify the references and add references from the last three years.

Response 7: Thank you to the reviewer for pointing out the issues. In the revised manuscript, we have added a substantial number of references from the past three years and updated the references.

Comments 8: There are many similar works reported in the previous literature, the authors should emphasize the novelty and better performance as compared to the previous work.

Response 8: Although there are numerous articles and review papers on biomass carbon recovery and its reuse, as well as many reports on TMD materials in fields such as energy catalysis, the preparation and application of two-dimensional MoS₂ and MoSe₂ are particularly popular, with a significant number of related research papers and reviews. However, efficiently combining the advantages of BMC, such as its abundant resources and controllable structure, with MoS₂/MoSe₂ can significantly enhance the performance of MoS₂/MoSe₂ in HER and SIBs, and greatly promote the preparation for large-scale applications in the future.

The novelty of biomass carbon-based MoS₂/MoSe₂ lies in leveraging the abundant, renewable, and structurally tunable properties of biomass carbon (BMC) to create a more efficient composite material. Compared to previous works, the integration of BMC with MoS₂/MoSe₂ provides several advantages, including enhanced electron conductivity, improved catalytic activity, and better structural stability. These features result in significantly improved performance in HER and SIBs. Additionally, the eco-friendly and scalable nature of BMC makes this composite more suitable for sustainable and large-scale energy applications.

Comments 9: Some figure quality is low, the authors should improve it.

Response 9: Thank you for the reviewer’s suggestions. We have adjusted the resolution and relevant information of the figures in the manuscript.

Comments 10: The authors should improve the language of the manuscript carefully.

Response 10: We have carefully revised the entire manuscript to avoid grammatical and other language-related issues.

Reviewer 3 Report

Comments and Suggestions for Authors

In this manuscript, Pan et al. reviewed the incorporation of biomass-derived carbon to improve the structure of Mo-based sulfides and selenides, enhancing their electrocatalytic performance in HER (Hydrogen Evolution Reaction) and SIBs (Sodium-Ion Batteries). Currently, the preparation of two-dimensional transition metal chalcogenides and their electrochemical applications are a topical research area, and this review is likely to attract a broad range of potential readers engaged in this field. Based on these considerations, I would like to recommend its publication at the journal Catalysts. However, to improve the manuscript, some minor issues detailed below are suggested to be addressed.

1. Other applications of MoS₂/MoSe₂ can be incorporated into your introduction, which would strengthen the contextual foundation of your research on TMDs.

2. MoS₂/MoSe₂ have many application scenarios, so what makes the authors believe these materials are more suitable for HER and SIBs?

3. For Figure 2, what is the guiding significance of preparing BMC into materials with different dimensions for this work?

4. How can BMC regulate the electronic structure of MoS₂/MoSe₂?

5. Machine learning has also been a research hotspot in recent years for assisting in the preparation and screening of materials. Could the authors provide some relevant connections to this work in the conclusion section?

Author Response

For review article

Response to Reviewer 3 Comments

1. Summary

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Is the work a significant contribution to the field?

Is the work well organized and comprehensively described?

Is the work scientifically sound and not misleading?

Are there appropriate and adequate references to related and previous work?

Is the English used correct and readable?

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: In this manuscript, Pan et al. reviewed the incorporation of biomass-derived carbon to improve the structure of Mo-based sulfides and selenides, enhancing their electrocatalytic performance in HER (Hydrogen Evolution Reaction) and SIBs (Sodium-Ion Batteries). Currently, the preparation of two-dimensional transition metal chalcogenides and their electrochemical applications are a topical research area, and this review is likely to attract a broad range of potential readers engaged in this field. Based on these considerations, I would like to recommend its publication at the journal Catalysts. However, to improve the manuscript, some minor issues detailed below are suggested to be addressed.

Other applications of MoS₂/MoSe₂ can be incorporated into your introduction, which would strengthen the contextual foundation of your research on TMDs.

Response 1: Thanks for the comment. We have added the other application in the revised manuscript. The specific changes are as follows:

MoS₂ and MoSe₂, as key members of the TMD family, exhibit versatile properties that make them valuable in various fields beyond electrochemical energy storage, such as optoelectronics, sensors, flexible electronics, lubricants and so on [31]. For example, MoS₂ and MoSe₂ are also utilized in chemical and biological sensors due to their large surface area and high sensitivity to environmental changes. They have been used to detect gases, biomolecules, and other analytes with high sensitivity and selectivity.

Comments 2: MoS₂/MoSe₂ have many application scenarios, so what makes the authors believe these materials are more suitable for HER and SIBs?

Response 2: Thanks for the comment. MoS₂ and MoSe₂ are highly versatile materials with a wide range of applications, but several intrinsic properties make them particularly well-suited for hydrogen evolution reactions (HER) and sodium-ion batteries (SIBs). First, MoS₂ and MoSe₂ have a layered structure that provides a high surface area and exposes a large number of edge sites, which are highly active for catalysis. For HER, the edge sites in these materials are known to facilitate the adsorption and reduction of protons to hydrogen, making them efficient catalysts. The layered structure of MoS₂ and MoSe₂ also plays a key role in SIB applications. These materials provide well-defined ion diffusion pathways between layers, which can accommodate large Na⁺ ions. The interlayer spacing of MoS₂ and MoSe₂ can be adjusted or expanded, allowing better accommodation of sodium ions, which are larger than lithium ions. Second, both materials possess semiconducting properties that can be modulated by defect engineering, doping, or phase transitions (e.g., 2H to 1T phase). This tunability allows for the optimization of their electronic conductivity and catalytic activity, which are critical for improving HER efficiency. MoS₂ and MoSe₂ exhibit high theoretical capacities for sodium-ion storage due to their ability to undergo reversible conversion reactions with Na⁺ ions. Additionally, their structural integrity can be preserved over multiple charge/discharge cycles, making them highly stable as electrode materials for SIBs. Finally, the earth abundance and cost-effectiveness is also the advantage.

Comments 3: For Figure 2, what is the guiding significance of preparing BMC into materials with different dimensions for this work?

Response 3: Thanks for the comment. By adjusting the dimensions of biomass carbon materials, you can tailor their physical and chemical properties, such as surface area, porosity, and mechanical strength. This customization is crucial for optimizing their performance in various applications, such as adsorption, catalysis, or energy storage. In addition, the dimensional properties of biomass carbon materials can impact their efficiency in processes like filtration, battery performance, or as a catalyst. For instance, materials with nanoscale dimensions often exhibit enhanced electrical conductivity and catalytic activity.

Comments 4: How can BMC regulate the electronic structure of MoS₂/MoSe₂?

Response 4: We have accordingly revised to emphasize this point. Biomass carbon can donate or accept electrons, altering the charge distribution in MoS₂/MoSe₂. This can lead to changes in their electronic band structure, potentially enhancing their electrical conductivity or modifying their electronic properties for specific applications. When biomass carbon is combined with MoS₂/MoSe₂, it can create interfaces that impact the electronic interactions between the two materials. This can modify the electronic band alignment, influencing the charge transfer efficiency and overall electronic behavior.

Comments 5: Machine learning has also been a research hotspot in recent years for assisting in the preparation and screening of materials. Could the authors provide some relevant connections to this work in the conclusion section?

Response 5: We have accordingly modifiedto emphasize this point. Machine learning algorithms can analyze large datasets to identify promising compositions or synthesis methods for MoS₂ and MoSe₂. This can speed up the discovery of optimal material formulations for enhanced performance in SIBs and HER. The models can predict the properties and performance of different MoS₂ and MoSe₂ materials based on their structural and compositional features. This can guide experimentalists in selecting the most promising candidates.