Optimization of Plasmonic Copper Content at Copper-Modified Strontium Titanate (Cu-SrTiO3): Synthesis, Characterization, Photocatalytic Activity
Round 1
Reviewer 1 Report
In this paper, the authors modified the SrTiO3 photocatalyst with different amounts of CuOx nanoparticles. The structure characterization and performance evaluation were performed. However, the conclusion and explanation obtained are not clear and need more supports. The improvements of the paper are required before considering publication. My suggestions are as follows:
1. All experiments in this paper were done under UV illumination, which is not in accordance with their Introduction part, the importance of photocatalytic efficiency under visible light and the modification can improve the performance under visible light. The author may try to compare the photocatalytic performance of these catalysts under visible light.
2. Table 1. Please align the content in first row for better readability. And the first SRT2 should be SRT1.
3. Line 129-131. Any characterization or literatures to support your explanation of low specific surface area of SRT025 compared to SRT0? I mean the porosity of SRT0.
4. Line 118, Cu nanoparticles or CuOx? Please doublecheck the whole manuscript.
5. For part 2.3. Detection of hydroxyl radical, the author mentioned higher hydroxyl radical production capacity from surface CuOx, so why higher Cu content (more than 1%) gives lower performance? The author may show data in Fig 7 for all different catalysts.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This manuscript reports the Optimization of plasmonic copper content at copper-modified strontium titanate (Cu-SrTiO3) of surface-modified SrTiO3 photocatalyst performed by copper deposition and studies their photocatalytic activity.
However, the results do not support conclusions. Moreover, there is a huge discrepancy between different results and discussions.
A major revision is suggested before further considering the manuscript for publication.
1. The introduction should be revised with more concise and specific descriptions; some statements are unclear. For example, ‘’SrTiO3 is a typical semiconductor photocatalyst oxide, which has relatively high photocatalytic activity in the UV region, but modification is required to increase the activity’’ is confusing.
2. Figure 4, TEM analysis doesn’t show anything the authors described in the text. For instance, ‘’ In the pictures, the surface Cu nanoparticles (d=~5-40 nm) are clearly visible on the surfaces of spherical SrTiO3 particles (d=~500-1500 nm).’’ How can authors see the surface roughness on black nanoparticles?
3. As described in XRD results, Cu deposition doesn’t affect the crystal properties of the SrTiO3. Moreover, the existence of Cu cannot be evidenced with EDX studies only; Authors should provide TEM mapping.
4. It is reported that Cu modifies the surface of the SrTiO3. It is highly expected the surface electronic properties of the SrTiO3 will be changed after Cu deposition. Authors should provide a detailed XPS analysis of the Cu-SrTiO3.
5. Photocatalytic activity of Cu-SrTiO3 over 90 min is not sufficient; Authors should provide prolonged activity results.
6. Stability is an important factor for practical applications. Authors are suggested to provide detailed stability of the best performing catalyst.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I'm good with current version.
Author Response
We would like to thank again the valuable discussions on this manuscript.
Reviewer 2 Report
The authors made some changes based on suggestions from the first round of revision. Specially the photocatalytic activity results have been improved with stability evaluation and some additional characterizations. However, there are some concerns to be resolved before the manuscript can be considered for publication.
1. The abstract does not appear to meet publishing criteria; rather, it appears to be a summary of the results reported. It should be more informative and concise, with fewer results. For example, the first two sentences should comment on the present literature's importance/problem, followed by what has been reported in this study.
2. The manuscript is not properly organized. Normally, the introduction section is followed by the materials and methods, results, and discussion sections. However, in this article, the materials and method section is placed somewhere in the results discussion sections. It is advised that authors carefully read the instructions before the next revision.
3. Authors are advised to merge 2-4 images in one figure for the convenience of the readers and better presentation rather than making each individual image a separate figure.
4. Figure 3, mapping, is presented in a revised version; that appears unusually brighter; it appears that the authors have modified the original mapping figure. Furthermore, the figure does not adequately captioned, which lacks the information of the type of mapping results. Authors are suggested to explain this odd color for mapping.
5. Manuscript lacks sufficient literature citations, authors are suggested to cite some recent paper, such as ACS Appl. Mater. Interfaces 2020, 12, 6343−6350, Advanced Energy Materials. 2021; 11:2003159, Solar Energy Materials & Solar Cells 222 (2021) 110952, ChemElectroChem, 2017;4:3126.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
