Photocatalytic Decomposition of Acetaldehyde on Different TiO2-Based Materials: A Review
Round 1
Reviewer 1 Report
The review of Tryba et al. focuses on the photocatalytic degradation of acetaldehyde over TiO2-based catalysts, discussing in particular the role of the TiO2 phases, preparation and modification approaches on the photocatalytic performances and the reaction mechanisms involved.
In my opinion the review is honestly written, with a good and up-to-dated state of the art. However, I think that the text is hard to follow, appearing often flat, with too much word and an insufficient number of figures from the reported literature. The presence of some figures would certainly increase the readability, making it more interesting.
Moreover, a second concern derives from the fact that most of the chapter 3, dealing with the adsorption experiments (with all tables and figures included in the review) appears as new data of the same authors, with no clear reference to the literature provided. Is this true or not? In my opinion this is quite disturbing, in so as a review should discuss prevalently of data before reported in the literature.
Following these consideration, my suggestion is: major revision.
Author Response
We agree with the Reviewer, that in the submitted manuscript any figures from the cited literature were not placed and this text is hard for reading, therefore we extended the presented data and added some figures from the other papers.
We also agree with the Reviewer, that in this paper we reported some new data (in chapter 3). We decided to do it, because these data are complementary with this review, they were not published yet, but all the presented new experiments were performed on the commercial samples, so we do not plan to publish it in the separated paper. The explanation, that these data are new and they were not published elsewhere was clearly added in the manuscript.
Reviewer 2 Report
The paper presents very interesting systematic review on the photocatalytic decomposition of acetaldehyde on different TiO2 based materials. I think that authors have done a great effort studying the photocatalytic performance of these type of catalysts.
Nevertheless, there are still some doubts or ambiguity which should be clarified before publication.
In the chapter 3 (Adsorption of acetaldehyde and its photocatalytic transformation on TiO2) the authors present the results of their research. Although this part is interesting it requires few corrections. In Figures 1 and 2 there is no description of the particular IR spectra. What is more, the designation of individual colours with respect to the references TiO2 samples should be added. Spectra frequency descriptions also need to be corrected – for example – 1362 cm -1 is sufficient accuracy. There are no units in the axis descriptions.
In Table 2, authors should add an additional column with values of acetaldehyde decomposition after 1 h (%) for all TiO2 samples. For KRONOClean®7050 sample CO2 formation after 1 h is the same like after 10 h, does it mean that acetaldehyde decomposition (%) after 1 h was already 35%?
Overall, I find this work interesting, the conclusions well supported, and pertinent, in scope to the Catalysts. Thus, I am happy to recommend the publication of this manuscript with minor corrections.
Author Response
Description of the IR spectra have been done. The descriptions of spectra frequency were correted, where it was necessary, the lack of accuracy was caused by the fact, that most od the IR bands were not sharp, just fuzzy and it was not easy to set up the exact value. X axis has unit, Y axis is without unit description, because absorbance is expressed as log(I0/I), so it is expressed without unit.
The process of acetaldehyde decomposition was carried out under continuous flowing of acetaldehyde gas. The difference between 1h and 10 h are from the kinetics of the process and the time needed to balance the concentration in the reactor, at very low flow of gas, there is a time necessary to reach equilibrium in all the volume of gas in the reactor. Therefore we put in the Table the values after the stability. The stability was reached for all the samples at the different time, we selected 10 hours to compare it with stable CO2 formation, however much earlier this stability was achieved. After 10 hours it was possible the compare the yield of the process among the samples. The explanation of this was added to the text.
Reviewer 3 Report
This review written by Tryba and co-workers, describes in a clear and orderly way, the decomposition of acetaldehyde on Tio2 besed materials. The authors have divided this topic into various chapters, ranging from the preparation of materials, to the mechanism of absorption, to the effect on their use in presence of oxygen and different wavelengths of irradiation.
To facilitate reading, I recommend inserting more figures, schemes or chemical formulas.
Improve the quality of Figures 1 and 2
In Figure 3, uniform characters of part a and b
For these reasons I believe that it can be published after minor revisions
Author Response
Additional figures, schemes and formulas were added to the text. The quality of figures was corrected.
Reviewer 4 Report
The application of photocatalysis in the control of air quality and in the conversion of gaseous products is of great interest and relevance. Despite the great variety of semiconductors and nanostructures that have been incorporated as photocatalysts, TiO2 continues to be the most used. I really liked the organization of the article. Although some paragraphs are redundant, I think the authors have done a great job. My only recommendation is to include in the conclusions a brief summary of the aspects related to the influence of vacancies and adsorption mechanism in the acetaldehyde oxidation process, because it only refers to the experimental conditions and not to the characteristics of the photocatalysts or interactions.
Author Response
Aspects related to the influence of oxygen vacancies on the adsorption and the photocatalytic oxidation of acetaldehyde were added to the conclusions and also it was more discussed in the other parts of this review.
Round 2
Reviewer 1 Report
The authors modified the manuscript according to my comments and those of other reviewers, by adding new figures and correcting some errors. This strongly improved the quality of the paper.
I now recommend the publication of this paper in Catalysts.
