Solid-State Synthesis of ZnO/ZnS Photocatalyst with Efficient Organic Pollutant Degradation Performance

Round 1

Reviewer 1 Report

The comments are in the doc 

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

This is the responses to the reviewer on our manuscript. We have carefully taken the comments into consideration in preparing our revision, and hope the quality of our manuscript would meet the publication standard of Catalysts. All of modifications were marked in red in the revision. The following was the responses to reviewers’ comments.

Thanks for the constructive comments.

 

 

 

 

Responses to reviewers’ comments:

Reviewer #1:

1. Please start the Abstract with a short introduction of the current problem(s) and the solution, based on the current study, in one or two lines.

Response：Thanks for this suggestion. The Abstract has been started with a short introduction of the current problem and the solution.

2. The research idea seems interesting, but the set goals are not achieved. The authors should clarify in the Introduction section what the novelty of their work is. What is the paper's central significance in comparison to related published works?

Response：Thanks for your suggestion. The novelty of their work is that a simple and green low-heat solid-phase chemical method was employed to synthesize ZnO/ZnS photocatalysts, which has been clarified in the Introduction section. In comparison to related published works, the paper's central significance is that ZnO/ZnS photocatalysts with efficient and broad-spectrum organic pollutant degradation performance was fabricated by a simple low-heat solid-phase chemical approach.

3. Compare this work with previous and similar research in terms of synthesis and application

Response：Thanks for your kind suggestion. Compare with previous and similar research in terms of synthesis and application, this work prepared ZnO/ZnS photocatalysts by a simple low-heat solid-phase chemical approach with efficient and broad-spectrum organic pollutant degradation performance.

4.The degradation products had better be determined. At least the TOC or COD values of the reaction system need to be provided

Response：Thanks for your valuable suggestion. As suggested, the degradation products should better be determined. However, Due to the COVID-19 epidemic, the TOC or COD values of the reaction system could not be carried out for the time being. However, we will supplement it when we have a chance to follow up.

5.The elemental mapping of the optimum composite needs to be provided.

Response：Thanks for your kind suggestion. As suggested, the elemental mapping of the optimum composite needs to be provided. However, Due to the COVID-19 epidemic, the elemental mapping of the optimum composite could not be conducted for the time being. However, we will supplement it when we have a chance to follow up. And, the XPS spectra results can also confirmed that the ZnO/ZnS photocatalysts was composited by Zn, O, S, and C elements.

6. Figure 6 Why do the ZOS-0.1 and 0.3 show lower activity for MO than RhB and tetracycline?

Response：Thanks for your kind suggestion. This is because the redox potentials of different degradation objects are different, and the properties of excited states after light excitation are also different. It may be that the conduction band of the ZOS-0.1 and 0.3 are more matched with the LUMO of RhB and tetracycline, so the activities are higher.

 

Reviewer 2 Report

The authors report a wet synthetic approach to making ZnO/ZnS photocatalyst for efficient organic pollutant degradation performance. The characterization of the interface, band structure, and mechanism study are well developed and straightforward. Therefore, I recommend the publication after the authors address minor editing and modifications.

 

Scientific questions:

1.       The title contained the word broad-spectrum. I assume this means the broad wavelength range absorption of the materials. Maybe this should be adjusted considering the photocatalysis reported here mainly work at UV irradiation.

2.       ZnO is well-known for the wide bandgap in the UV region. Theoretical calculation from the authors reports a bandgap of 2.45 eV (Fig. 7c). Could the author explain this discrepancy between the calculation and their experimental measurement?

3.       The authors report the photocurrent measurements using a CHI 660B electrochemical workstation, but do not specify the working electrode, counter electrode, and electrolyte. Could the authors be more specific about the experimental conditions for this measurement?

 

Non-scientific comments:

1.       The written English needs improvement to present the beautiful results. Here are several examples:

i.                     (Line 11-12, first sentence of abstract) “To improve the separation efficiency of ZnS photogenerated carriers, ZnO/ZnS photocatalyst was prepared by solid-phase approach, and the structure and morphology were systematically studied.” → ”To improve the separation efficiency of photogenerated carriers in ZnS, ZnO/ZnS photocatalyst was prepared by a solid-phase approach, with the structure and morphology systematically studied.”

 

ii.                   (Line 228) “To further insight into the VBM and CBM compositions of the photocatalysts” → ”To further investigate into the VBM and CBM compositions of the photocatalysts.”

 

iii.                 (Line 245-247) “On the contrary, when the fluorescence intensity is low…generated carriers is low” → “And vice versa.”

 

2.       The abbreviations should be explained at their first presence in the article.

i.                     (Line 62-63) ”The photocatalytic activity … using MO, RhB and …” → “The photocatalytic activity … using Methylene Orange (MO), Rhodamine B (RhB) and …”

ii.                   The authors should add one sentence explaining they refer to the ZnO/ZnS before line 83 and somewhere in the caption of Figure 2.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

This is the responses to the reviewer on our manuscript. We have carefully taken the comments into consideration in preparing our revision, and hope the quality of our manuscript would meet the publication standard of Catalysts. All of modifications were marked in red in the revision. The following was the responses to reviewers’ comments.

Thanks for the constructive comments.

 

 

 

 

Responses to reviewers’ comments:

Reviewer #2:

1. The title contained the word broad-spectrum. I assume this means the broad wavelength range absorption of the materials. Maybe this should be adjusted considering the photocatalysis reported here mainly work at UV irradiation.

Response：Thanks for your kind suggestion. As suggested, the word broad-spectrum may not be appropriate. Hence, the titled has been modified as “Solid-state synthesis of ZnO/ZnS photocatalyst with efficient organic pollutant degradation performance”.

2. ZnO is well-known for the wide bandgap in the UV region. Theoretical calculation from the authors reports a bandgap of 2.45 eV (Fig. 7c). Could the author explain this discrepancy between the calculation and their experimental measurement?

Response：Thanks for your valuable suggestion. The literature research shows that the main reason for the small band gap value is the discontinuity of the wave function at the maximum value of the valence band and the minimum value of the conduction band of the semiconductor.

3. The authors report the photocurrent measurements using a CHI 660B electrochemical workstation, but do not specify the working electrode, counter electrode, and electrolyte. Could the authors be more specific about the experimental conditions for this measurement?

Response：Thanks for your kind suggestion. In the electrochemical measurement, three electrodes system including Ag/AgCl electrode, Pt sheet, and FTO glass coated with different samples were used as reference electrode, counter electrode, and working electrode, respectively. which has been provided in the Materials and Methods section.

4. The written English needs improvement to present the beautiful results. Here are several examples:
5. (Line 11-12, first sentence of abstract) “To improve the separation efficiency of ZnS

photogenerated carriers, ZnO/ZnS photocatalyst was prepared by solid-phase approach, and the structure and morphology were systematically studied.” → ”To improve the separation efficiency of photogenerated carriers in ZnS, ZnO/ZnS photocatalyst was prepared by a solid-phase approach, with the structure and morphology systematically studied.”

1. (Line 228) “To further insight into the VBM and CBM compositions of the photocatalysts” → ”To further investigate into the VBM and CBM compositions of the photocatalysts.”

iii. (Line 245-247) “On the contrary, when the fluorescence intensity is low…generated carriers is low” → “And vice versa.”

Response：Thanks for your kind suggestion. As suggested, the written English have been improved.

5. 5. The abbreviations should be explained at their first presence in the article.
6. (Line 62-63) ”The photocatalytic activity … using MO, RhB and …” → “The photocatalytic activity … using Methylene Orange (MO), Rhodamine B (RhB) and …”
7. The authors should add one sentence explaining they refer to the ZnO/ZnS before line 83 and somewhere in the caption of Figure 2.

Response：Thanks for your valuable suggestion. The abbreviations have been explained at their first presence in the article.