Insight into the Structural and Performance Correlation of Photocatalytic TiO2/Cu Composite Films Prepared by Magnetron Sputtering Method
Kenichi Kaminaga
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsAuthors developed TiO2/Cu films with varying Cu content using magnetron sputtering co-deposition. Adding Cu improved the films' antibacterial properties and visible light response. The study examined how different Cu levels affected the films' structure, surface properties, and performance.
However, the methodologies employed for measurement and evaluation demonstrated notable deficiencies, particularly in the XRD analysis of crystal structures. Publication of the manuscript in its current form is unlikely without a more rigorous re-examination and re-measurement process.
Q1 (L165):
The observed shift in Si substrate peak positions between TiO2 and Cu10 samples raises doubts about the authors' attribution of the TiO2 (110) peak shift in Cu10 to Cu doping. Furthermore, the too weak Si substrate peaks and the markedly weaker TiO2-derived peaks in Cu15 and Cu20 samples suggested potential misalignment during XRD measurements. For thin film XRD analysis, it is imperative to normalize substrate peak intensities across samples and conduct a comparative analysis of thin film-derived peak positions and intensities. A re-evaluation of XRD measurements and subsequent reassessment of Cu concentration dependence is essential.
Q2 (L199):
XPS data alone is insufficient to distinguish between surface segregation and lattice substitution of Cu in TiO2. Elucidation of Cu distribution requires depth profiling techniques such as XPS depth analysis or SIMS.
Q3 (L217):
The correlation between increased Cu concentration and observed crystal grain formation in SEM images necessitates further investigation. SEM-EDX analysis should be employed to confirm whether these grains result from Cu surface segregation.
Q4 (L269):
The manuscript lacks a discussion on the anomalous maximum contact angle observed for Cu10. This phenomenon should be examined in the context of potential Cu surface segregation, as indicated in Q2 and Q3. Additionally, the contact angle scatter diagram in Fig. 8 inappropriately connects data points of independent samples. The x-axis represents discrete sample names, precluding the use of connecting lines between plotted points.
Q5 (L312, L315):
The current > 40 nm interval between data points in the absorption spectra acquisition is excessively large, resulting in substantial error margins for band gap values derived from Tauc plot extrapolations. This imprecision precludes meaningful sample comparisons. A re-measurement of UV-visible spectroscopy with higher resolution is necessary.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis work studies the effects of Cu contents in TiO2/Cu films on the photocatalystic disinfection. This work can be accepted to publish if the below comments can be addresed:
1. The typo of sample names in all Tables should be corrected (all the sample neames are Cu10).
2. In line 183, Fig. 4(b) should be corrected to Fig.4(d).
3.The XPS for Cu2p shows high intensity of Cu2+ satellite, indicating the dominate presence of CuO, where the 2 theta of around 36 degree in XRD could be CuO (111) plane. The authors have to confirm the structure.
4. There are too many Figures in the manuscript, some figures should be combined to be a single Figure with labels Fig.1a, 1b or 1c.
5. The results and discussion are not consistent. For example, imoroved roughness did not completely enhance the antibacterial performance.
6. The antibacterial tests wereconducted in dark condition, which can not confirm the photocatalystic effect. The author should compare the antibacterial properties in both dark and light conditions.
Comments on the Quality of English LanguageGreat
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsIt appears that the issues I highlighted in the previous version have been adequately addressed through re-measurement. Therefore, I recommend that this revised version be published.
Author Response
We feel great thanks for your professional review work on our article. We greatly appreciate your recognition, which is of significant importance to us. Once again, thank you for your valuable time and effort in our work.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe contact angle measured in Fig. 7b is inconsistent with the photo image, where requires to modify.
Author Response
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Author Response File: Author Response.pdf
