Black Phosphorus/WS2-TM (TM: Ni, Co) Heterojunctions for Photocatalytic Hydrogen Evolution under Visible Light Illumination
, İlknur Aksoy Çekceoğlu 1, Emre Aslan 4, İmren Hatay Patır 1,* and Onder Metin 2,3,5,*
Round 1
Reviewer 1 Report
Although the contents of the manuscript were scientifically correct, I think several revisions are required before the publication.
Here I list my comments.
1) While the authors mention that theoretical loading rations of transition metals are indexed (Line 141), they also seem to use ICP-MS analysis to estimate weight ratio of transition metal cocatalysts (Line 310). This is confusing.
2) BP/WS2-15 is suddenly appears in the caption of Figure 1 and then frequently appears before the explanation that this is BP/WS2 catalyst with 15% BP mass ratios (Line 278-288). The authors should mention the explanation of BP/WS2-15 before showing the data of this.
3) The authors measured HAADF-STEM image (Figure S1) for analyzing elemental distributions. However, I cannot understand the necessity because there seems to be no elemental information in Figure S1.
4) Although the authors mention the diffraction peak at 2 theta = 13.89° shown in XRD is attributed to the (002) plane of 2H phase of WS2 (Line 200-202), they also mention that the diffraction peak at 2 theta = 13.89° is an additional peak (Line 203-205). This is confusing.
5) Although the authors mention that there are two peaks in S 2p XPS (Figure 3(c)) (Line 240-241), the raw date is very noisy and seem not to have any peaks. Therefore, I think the deconvolution of S 2p XPS is impossible and meaningless. S 2p XPS in Figure S4 is also the same.
6) Although the lifetime is indexed, the time resolved photoluminescence spectra seems to be similar (Figure 4(b)). So, please arrange to show the difference more clearly. In addition, the data of BP seem to have a shoulder. What is the origin of this?
7) I want to know how long your photocatalyst can keep producing hydrogen because EY gradually degrades (Line 337-338) and photocatalytic reaction will stop when EY was completely degraded.
8) In Line 340-342, the authors mention that the adsorption spectral results are compatible with the photocatalytic hydrogen production. I think the photocatalyst less decompose EY is better because photo-generated carriers were used to produce hydrogen rather than decomposition of EY. If my recognition is correct, please add this point in the revised manuscript.
9) In Figure 5 (c), which sample shows the gray colored data?
10) Please use the same colors to distinguish same samples among Figures. The authors use yellow, black, and gray for BP in Figure S7, S8, S9. This is confusing.
11) There are several careless mistakes such as unnecessary spacing (Line 182, Line 213, Line 285) and highlight (Line 306). Please check carefully not to leave such mistakes in the revised manuscript.
Author Response
Thanks to the Reviewer for his/her effort to examine our manuscript and provide valuable comments to improve the quality of our manuscript. We appreciated all the revisions indicated by the reviewer and re-organized the manuscript accordingly. Our responses to the Reviewer’s comments are in the attached file entitled "Response to Reviewers"
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript describes synthesis of black phosphorus/WS2-TM (TM: Ni, Co) composite photocatalysts for the hydrogen evolution under visible light. In principle, the proposed systems are quite new, good activity has been achieved, but a number of questions arise regarding the design of the article and the presentation of the results.
1. Too many significant digits in values of activity. E.g., 9.5264 mmol h-1g-1 should be 9.53 mmol h-1g-1.
2. Why was Eosin dye added if photocatalysts themselves absorb visible light?
3. The article should present diffuse reflectance spectra in the UV-Vis range for solid photocatalysts.
4. In XRD patterns all peaks should be clearly labeled.
5. What are the explanations for the fact that hydrogen production schedules plateau over time?
6. More concrete evidence for the formation of S-scheme heterojunctions must be given.
Author Response
Thanks to the Reviewer for his/her effort to examine our manuscript and provide valuable comments to improve the quality of our manuscript. We appreciated all the revisions indicated by the reviewer and re-organized the manuscript accordingly. Our responses to the Reviewer’s comments are in the attached file entitled "Response to Reviewers"
Author Response File: Author Response.pdf
Reviewer 3 Report
Recommendation: Major
The authors reported for the first-time the fabrication of ternary heterojunctions doped with first-row transition metals (BP/WS2-TM (TM: Ni, Co)) for photocatalytic HER under visible light irradiation. The writing is quite good. The characterizations and explanation are also ok. I agree to accept this manuscript after solving the following concerns:
1. “ml” should be “mL” in L146.
2. The equation 1 should be rechecked.
3. It is not easy to figure out the Ni and Co nanoparticles in Figure 1e and 1f, try other methods.
4. Provide the corresponding TEM images of STEM-EDS element mapping images (Figure 1g-f). Reference like Appl. Catal. B: Environ. 2022, 303, 120887.
5. Please explain the new peak at around 36 degrees in BP/WS2-25.
6. The peak of S 2p is too weak, redone.
7. Recheck the sentence “HER activity under solar light (420 nm) compared to” in L299.
8. Tables for comparison of activity with other materials should be provided. Several important references related to hydrogen production should be referred (Renewable and Sustainable Energy Reviews, 2020, 132, 110040; Molecules, 2022, 27, 4241; Chem. Eng. J., 2023, 456, 141032.).
9. The band position of materials should better be characterized by experiments in this manuscript.
10. Without EY, is there any activity?
11. How to prove that the existence of heterostructure?
quite good, need a little polish
Author Response
Thanks to the Reviewer for his/her effort to examine our manuscript and provide valuable comments to improve the quality of our manuscript. We appreciated all the revisions indicated by the reviewer and re-organized the manuscript accordingly. Our responses to the Reviewer’s comments are in the attached file entitled "Response to Reviewers"
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Concerns have not been well solved.
Minor editing
Author Response
1) Concerns have not been well solved.
Our response: We do not agree with the reviewer on this issue. We believe that the revised manuscript is included all the revisions indicated by the reviewer 3 and all other reviewers. In this regard, we believe that the current version of the manuscript is scientifically adequate to be published in the Catalysts journal.
2) Minor editing is needed on the English of the manuscript.
Our response: The language of the manuscript was rechecked by all authors and necessary corrections were made to improve the English of the manuscript.
