Effect of Ce-Doping on Microstructure and Adsorption- Photodegradation Behaviors of the Hydrothermally-Synthesized TiO2 Nanotubes
Round 1
Reviewer 1 Report
Dear Authors,
The manuscript „Effect of Ce-doping on microstructure and adsorption- photodegradation behaviors of the hydrothermally-synthesized TiO2nanotubes” addresses an investigation on the photodegrading behavior of Ceria doped Titanium oxide nanotubes. The experimental procedures are described, followed by a morphological characterization of the obtained nanotubular product an extensive characterization of their electronical and photodegradation properties.
The description of the experiments covers all important topics, as well as the conclusions drawn seem to be correct. Thus, I regard the manuscript as an work of high quality recommendable for publication.
Nevertheless, I have to object several details.
First, the description of the synthesis procedure for the TNT´s is incomplete. The volume of the stainless-steel reactor as well as the volume of the NaOH solution used should be added to the manuscript.
Secondly, the sample preparation procedure for the TEM measurements is lacking. Which type of sample carrier was used? How were the nanotubes dispersed on the carrier? Obviously, for the images in Fig.1, TEM mode was applied. This should be stated in the text or the Figure caption, as for the EDS measurements in Fig. 2, STEM was used as the imaging technique.
Figure 2 does not show an EDS analysis, but an EDS mapping. This should be corrected in the Figure caption. However, it is not clear where the EDS spectrum also incorporated in Fig. 2 was recorded. Is it the sum spectrum of the area covering the maps shown? Or was it recorded as a point measurement somewhere on the sample? This information is lacking in the manuscript.
In the EDS spectra shown, X-ray lines of additional elements are present. Carbon and copper might come from the sample carrier grid used, but unfortunately, the information on the type of carrier grid used is lacking. Sodium and Silicon are also observed. Where do they come from? Are these elements present in the sample, ore are these elements evenly distributed on the carrier grid? EDX maps of Sodium and Silicon have to be added to Fig. 2, and the source of the observation of these elements has to be clarified. I regard the omitting of these elements as a severe shortcoming of the manuscript, which has to be covered in a revised version.
Thirdly, some information on the XRD measurements is also lacking. Which focusing geometry was used? How was the filtering of the radiation achieved (Ni filter, secondary monochromator or energy dispersive detector)? Were the reflections in Fig. 3 assigned by ab-inito indexing, calculation or by database comparison? Which database bas used? Nevertheless, despite this information is missing, the results are conclusive.
Also, some information is missing on the absorption and photochemical tests. What concentration of Methylene blue wa used for the absorption test and the photocatalytic test.
Thus, I ask you to complete the missing experimental information and clarify the source and spatial distribution of the elements Carbon, Copper, Sodium and Silicon observed in TEM and discuss their influence with respect to the results obtained.
Author Response
Dear reviewer 1.
We carefully revised the mamuscript according your kind suggestions.
The details can be found in the text.
Reviewer 2 Report
Authors of the paper ‘Effect of Ce-doping on microstructure adsorption-degradation behaviors of the hydrothermally-synthesized TiO2 nanotubes’ prepare Ce-doped TNT and study their surface, mechanical properties, adsorption ability and methylene blue degradation under different conditions.
I have several issues about cited references and English. This is why I recommend minor revision before the paper can be published.
1. The text of the Manuscript is rich in typos – missing or extra gaps, capital letters instead of small letters, missing dots, etc. Please revise the whole text and fix all these small mistakes.
2. Formula should be embedded in the Manuscript text as an editable text through the instrument ‘creation of formula’, not as figures. Maybe the copy I have performs a low resolution, but the formulaу (1) (4) (5) look all blurred and dirty.
3. Inappropriate citation of references. I have spotted, for example:
3.1. Authors claim that papers [7-10] describe TiO2 doped with Al, Zn and REEs. However, I did not find among papers [7-10] those where TiO2 would be doped with REE.
3.2. The reference [29] does not contain equations (2) and (3), as authors claim.
3.3. The reference [30] does not contain equation (4), as authors claim.
3.4. The authors use ref. [31] to show how TiO2 nanotubes form at all. However, I did not find these details in paper [31]. It demonstrates influence of pores size on absorption capacity of the tubes. I believe the TNT formation mechanism was suggested much earlier than 2008 year.
Please, be more careful with cited literature.
Author Response
Dear reviewer 2.
Your suggestions are very good. We carefully revised the manuscript un der your suggestions. Thank you.
Author Response File: 
Author Response.docx
Reviewer 3 Report
In this paper, “Effect of Ce-doping on microstructure and adsorption- photodegradation behaviors of the hydrothermally-synthesized TiO2 nanotubes,” the authors synthesized Ce-TNTs by a hydrothermal method to obtain a high-efficiency adsorption and photodegradation abilities for MB dye. The obtained results indicate that the Ce-doped TNTs are composed of anatase tubulars with an inner-hole diameter of 5nm, outer diameter of 10-15nm, and length of several hundred nanometers and a small amount of CeO2 nanoparticles. Overall, this manuscript has a strong potential for another review round after applying the issues and addressing the shortcomings listed below:
1-The authors should polish/revise some grammatical mistakes and typos along the manuscript. I invite the authors to read their manuscript carefully and make the required changes where necessary.
2-In the Introduction section, while discussing recent developments in the field of nanoparticles for the removal of organic pollutants in water, the following work should also be considered and cited to give a more general view to the possible readers of the work: [(i) Controlled self-assembly of plasmon-based nanocrystals for high performance photonic technologies, Nano Today 37, 101072 (2021)].
3-For Equations 1 and 4: Rather than using an image of the equations, try to type the equations.
4-Try to separate panels of Figure 1 and make each panel size the same.
5-In Figure 2, put a label for each figure and the plot like Figure 2a, Figure 2b, etc. Also, increase the size of the plot.
6-For each plot, please increase the font size of the texts.
7-Put the inset of Figure 7b outside of the plot. In its current form, it affects the main figure (Figure 7b).
8-In Figure 8, put the equation outside of the plot.
Author Response
Dear reviewer 3.
We accept all of your suggestion and carefully revised the manuscript under your directions. The detailed information can be found in the text.
Thank you.
Author Response File: Author Response.docx
Round 2
Reviewer 3 Report
In its current form, the revised manuscript is suitable for publication.
