Photocatalytic Activity of ZnO/Ag Nanoparticles Fabricated by a Spray Pyrolysis Method with Different O2:N2 Carrier Gas Ratios and Ag Contents
, Nurdiana Ratna Puri 2, Sugeng Winardi 2, Widiyastuti Widiyastuti 2, Manabu Shimada 1 and Kusdianto Kusdianto 2,*Round 1
Reviewer 1 Report
The authors fabricated ZnO/Ag composite under different carrier gas conditions, and tested the photocatalytic activity for the composite material. There were a series of characterizations in this work, but the experiment was too simple, and there was not any mechanism investigation for the possible enhanced photocatalysis process. I suggest a rejection for this manuscript. Other comments are as follows:
1. I consider the title was not appropriate, and the title should be revised, expect for carrier gas ratios, the authors also studied the Ag content.
2. Keywords, only three words, why could not describe the main topics of the paper.
3. The conventional characterizations, such as SEM, XRD, TEM, BET, were conducted. However, the important photoelectricity tests should be supplemented, which could reflect the photocatalytic function and mechanism.
4. The design of performance experiment was too simple, and the results were not unreliable.
5. The discussion about the obtained result was too plain, and there was not any characterizations and experiments to confirm these poor result and discussion.
Author Response
First of all, we greatly appreciate to the reviewer for the valuable comments and suggestions for this manuscript. All revised words are highlighted in Red in the revised manuscript. Replies to the reviewers’ comments as well as our revisions are in separate sheets.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
A ZnO/Ag photocatalyst prepared by spray pyrolysis is reported in the manuscript. Nanoparticles prepared under different O2:N2 carrier gas ratios and their photocatalytic activities were investigated. The manuscript has a certain degree of innovativeness, reliable data and particular research value. However, some problems and mistakes in this article need to be explained and corrected.
1. Some sentences are incorrectly expressed, such as "the ZnLa, ZnKa, ZnKa and Oka" in line 111
2. It is very puzzling that no Ag particles are generated, but Zn particles are generated when the ratio of O2:N2 is 0:1. Why? However, when the ratio is 1:0, the situation is reversed. Why?
3. Ag is an active metal that is easily oxidized. How to judge whether AgO is formed when the ratio of O2:N2 is 1:0? The author needs to give some intuitive evidence, such as XPS and Raman analysis.
4. The authors need to provide the XPS of Ag/ZnO composites prepared at different O2:N2 ratios to determine the material composition, especially the XPS analysis results of Ag.
5. Why does the introduction of Ag significantly affect the ZnO particle size at a high O2 ratio?
6. In the manuscript, the author mentioned that excessive Ag loading would decrease the specific surface area, which is inconsistent with the results in Figure 6. Please correct it.
7. To confirm that Ag loading enhances the separated transport rate of photogenerated carriers, the authors must provide sufficient evidence. Such as steady-state fluorescence and photoelectrochemical tests.
8. The author needs to provide the UV diffuse reflectance data of the photocatalyst and the corresponding energy band structure to provide the basis for generating various active radicals.
9. The authors need to supplement the active species capture experiments and verify the material's cycling performance.
10. Suggestion: More recent papers involving photocatalytic environmental remediation can be referenced in the manuscript. (Liu C, Mao S, Wang H, et al. Chemical Engineering Journal, 2022, 430: 132806; Liu C, Mao S, Shi M, et al. Journal of Hazardous Materials, 2021, 420: 126613; Chemical Engineering Journal, 2022, 449: 137757).
Author Response
First of all, we greatly appreciate to the reviewer for the valuable comments and suggestions for this manuscript. All revised words are highlighted in Red in the revised manuscript. Replies to the reviewers’ comments as well as our revisions are in separate sheets (please see the attachment).
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
This manuscript has been improved.
Reviewer 2 Report
Authors addressed very well most of my comments. Paper could be published now.
