New BaTi_0.96Cu_0.02X_0.02O₃ (X = V, Nb) Photocatalysts for Dyes Effluent Remediation: Broad Visible Light Response

Round 1

Reviewer 1 Report

 

The manuscript reports new photocatalysts composed of BaTiO3, BaTi0.96Cu0.04O3, BaTi0.96Cu0.02V0.02O3, and BaTi0.96Cu0.02Nb0.02O3 powders that were prepared by solid-state reaction. The modification of BaTiO3 by (Cu, Nb) ions induced superior photodegradation properties for methyl green and methyl orange with an efficiency of 97% and 94% during 60 and 90 min under sunlight irradiation, respectively with high mineralization efficiency. Overall, I found the manuscript to be well-written and informative. It is a valuable contribution to the field of photocatalytic materials, with potential application in the environmental sector. However, I have some questions related to the content. Therefore, I suggest the manuscript requires minor revision to be published.

The comments are given below.

1- Clearly highlight the novel aspects of the proposed BaTiO3 modified with copper and niobium, system and how it differs from previously reported photocatalysts. This will help readers understand the significance and unique contributions of this research

2- Add a more detailed explanation of the applications and potential impact of the functional photocatalytic properties in the environmental field.

3- Provide a more straightforward comparison between your systems and previous works to emphasize the novelty of your approach.

4-The Scheerer formula is empirical and 1digit after the decimal has no meaning, Try the Williamson-Hall plot, it is more reliable for calculating the crystallite size.

5- The error bars must be presented in the Fig. 9 and d11.

6- What about Cu and Nb leaching during photodegradation? Did you carry out any analysis for the solution after treatment?

7- I noted that the kinetic plots are based on a linearization technique. Such linearization methods are outdated now in chemical kinetics, non-linear least squares fitting to the untransformed original equation should be used See the following article (DOI: 10.1007/s11144-022-02232-8).

8-There are some grammar and format mistakes found in the manuscript. Please check it thoroughly in the manuscript.

9- See the following references for an enriching of the bibliography section:

1)      10.1007/s11144-022-02232-8

2)      10.1155/2020/4815767

 

 

Author Response

1- Clearly highlight the novel aspects of the proposed BaTiO₃ modified with copper and niobium, system and how it differs from previously reported photocatalysts. This will help readers understand the significance and unique contributions of this research.

 Response to comment No. 1

• The novelty of the study was discussed in the final part of the introduction (highlighted in the revised manuscript).
• In the final part of the photocatalytic, the author added a comparison between the obtained results with some previous works to emphasize the good results of this study (highlighted in the revised manuscript).

 

2- Add a more detailed explanation of the applications and potential impact of the functional photocatalytic properties in the environmental field.

Response to comment No. 2

• The important of the functional photocatalytic properties in the environmental field (hydrogen production and depollution of environmental pollutants) was introduced in the introduction part (highlighted in the revised manuscript).

3- Provide a more straightforward comparison between your systems and previous works to emphasize the novelty of your approach.

 Response to comment No. 3

• In the final part of the photocatalytic, the author added a comparison between the obtained results with the previous works to emphasize the novelty (highlighted in the revised manuscript).

4- The Scherrer formula is empirical and 1digit after the decimal has no meaning, try the Williamson-Hall plot, it is more reliable for calculating the crystallite size.

Response to comment No. 4

• According to reviewer suggestion, the author used the Williamson-Hall method to calculate the crystallite size as shown in Figure 4 in the revised manuscript (highlighted in the revised manuscript).

5- The error bars must be presented in the Fig. 9 and d11.

 Response to comment No. 5

• The author added the error bars to both figures.

6- What about Cu and Nb leaching during photodegradation? Did you carry out any analysis for the solution after treatment?

Response to comment No. 6

• author will perform a future study on the best composition to investigate more photocatalytic properties on many dyes including leaching during photodegradation.

7- I noted that the kinetic plots are based on a linearization technique. Such linearization methods are outdated now in chemical kinetics, non-linear least squares fitting to the untransformed original equation should be used See the following article (DOI: 10.1007/s11144-022-02232-8). 

Response to comment No. 7

• According to reviewer comment, the author used the non-linear least squares fitting to study the kinetic performance (highlighted in the revised manuscript).

8- There are some grammar and format mistakes found in the manuscript, please check it thoroughly in the manuscript.

Response to comment No. 8

• The English language was modified in the total manuscript (highlighted in the revised manuscript). Hope that the modifications in the level required by the reviewer

9- See the following references for an enriching of the bibliography section:

1)      10.1007/s11144-022-02232-8

2)      10.1155/2020/4815767

 Response to comment No. 9

• The suggested references is very useful and important, the author added both references to the revised manuscript (References 1 and 2).

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Review of the manuscript Catalysts-2606624 for the Authors: This article deals with the synthesis of novel barium titanate-based materials for the degradation of industrially used dyes. The topic is interesting, the experimental work is robust, however some issues need to addressed before publication. Language and style also need to be heavily upgraded. Please see details below: Title – Although maybe too long it’s ok. Abstract – Please recheck it carefully because in the end you talk about Bismuth/Fe2O3 based catalysts?? Introduction – Provides a sufficient overview of the topic and highlights the novelty of your work, no need for interventions in this part expect language upgrades. Results and discussion – From the XRD data I would not say that you have 100% tetragonal BTO, since you seem to not have any peak splitting for the 38.8 2theta peak, which is quite characteristic for tetragonal BTO. In my opinion you have a mixture of cubic and tetragonal, which could be elucidated by a more in-depth analysis of the XRD or by the addition of a complementary technique like Raman to elucidate this? In other words, pay particular attention to make this correct and believable, otherwise I will suggest immediate reject in the second round. For the SEM EDX analysis would be useful to see the EDX of the pure BTO also, to compare with the doped samples. Optical data seems to be fine, and the photocatalytical experiment was conducted in depth and includes reusability and multiple cycles so also seems to be fine. But check line 288 again for Bi/Ba?? Preparation of samples and measurements – Maybe add more details for XRD, SEM, and spectrometer. Conclusions – When you address the XRD then rewrite, if necessary, this part in conclusion also. Literature – Up to date and sufficient. For now I suggest major revision.

Language and style also need to be heavily upgraded.

Author Response

Reviewer 2

 

1- Language and style also need to be heavily upgraded.

 

Response to comment No. 1

 

• The English language was modified in the total manuscript (highlighted in the revised manuscript). Hope that the modifications in the level required by the reviewer

2- Abstract – Please recheck it carefully because in the end you talk about Bismuth/Fe₂O₃ based catalysts??

 

Response to comment No. 2

 

• The abstract was carefully modified according to reviewer comment (highlighted in the revised manuscript).

 

3- Introduction – Provides a sufficient overview of the topic and highlights the novelty of your work, no need for interventions in this part expect language upgrades.

 

Response to comment No. 3

 

• The introduction was modified (language upgrades) according to reviewer comment (highlighted in the revised manuscript).

 

 

4- From the XRD data I would not say that you have 100% tetragonal BTO, since you seem to not have any peak splitting for the 38.8 2theta peak, which is quite characteristic for tetragonal BTO. In my opinion you have a mixture of cubic and tetragonal, which could be elucidated by a more in-depth analysis of the XRD or by the addition of a complementary technique like Raman to elucidate this? In other words, pay particular attention to make this correct and believable, otherwise I will suggest immediate reject in the second round.

 

Response to comment No. 4

• In many literature, the splitting of (002) and (200) was used to check the formation of tetragonal or cubic phase for pure, doped and codoped BaTiO₃.
• As well, the ratio of the lattice parameters (c/a) is used to analyze the phase of BaTiO₃.
• The XRD was modified and discussed according to reviewer comment (highlighted in the revised manuscript) as follow:

 

“For all samples, the splitting of (002) and (200) planes within 2θ = 44-46◦ (inset Figure 1) verifies the formation of tetragonal phase and ruled out the cubic phase (both planes combine in one peak) [26]. As presented in Table 1, the ratio of (c/a) supported the tetragonal phase for all samples.”

 

Figure 1. XRD analysis of (a): BaTiO₃, (b): BaTi_0.96Cu_0.04O₃, (c): BaTi_0.96Cu_0.02V_0.02O₃ and (d): BaTi_0.96Cu_0.02Nb_0.02O₃samples.

 

 

 

5- For the SEM EDX analysis would be useful to see the EDX of the pure BTO also, to compare with the doped samples.

 

Response to comment No. 5

 

• In this period, the EDX device is malfunction. I hope from the reviewer to consider this situation and accept the two analysis of the codoped samples.

6- Check line 288 again for Bi/Ba?? 

 

Response to comment No. 6

 

• The line 288 was corrected for Bi/Ba error (highlighted in the revised manuscript).

7- Preparation of samples and measurements – Maybe add more details for XRD, SEM, and spectrometer.

 

Response to comment No. 7

 

• More details for XRD, SEM, and spectrometer was added to the revised manuscript (highlighted in the revised manuscript).

 

8- Conclusions – When you address the XRD then rewrite, if necessary, this part in conclusion also.

 

Response to comment No. 8

 

• The conclusions was modified and discussed according to reviewer comment (highlighted in the revised manuscript).

 

Author Response File: Author Response.pdf

Reviewer 3 Report

In this article, several photocatalysts composed of BaTiO₃, BaTi_0.96Cu_0.04O₃, BaTi_0.96Cu_0.02V_0.02O₃ and BaTi_0.96Cu_0.02Nb_0.02O₃ powders were prepared by solid state reaction. BaTi_0.96Cu_0.02Nb_0.02O₃ catalyst shows a high mineralization efficiency and stability. This article is recommended for publication in Catalysts after major revision. Please find below the specific comments.

1. Experimental section including detailed preparation methods of the catalysts seems missing in this manuscript.

2. The author highlights in this manuscript several times that the piezoelectric behavior of BaTiO₃ facilitates effective charge separation. However, they didn’t show any direct evidence on charge separation. Experimental data such as PL spectra, photocurrent density variation, etc should be supplemented to prove such statement. Suggested references: (1) Nanomaterials 2022, 12, 904; (2) Chem. Eng. J. 2021, 424, 130444; (3) Nano Res. 2023, 16, 371-376; etc.

3. Line 42-44: Compared to those mentioned here, other more important visible-light driven photocatalyst materials are missing, for example Fe₂O₃, WO₃, g-C₃N₄, etc.

4. In view of the physicochemical properties of the doped photocatalysts after the reaction, further structural characterization data of the used catalysts are needed to prove the stability.

5. Conclusions section could be more concise.

Moderate editing of English language is required.

Author Response

1. Experimental section including detailed preparation methods of the catalysts seems missing in this manuscript.

 

Response to comment No. 1

 

 

• According to journal style, the Experimental section ( Preparation and measurements) is introduced in the final part of the manuscript before conclusion (highlighted in the revised manuscript).

 

 

2. The author highlights in this manuscript several times that the piezoelectric behavior of BaTiO₃ facilitates effective charge separation. However, they didn’t show any direct evidence on charge separation. Experimental data such as PL spectra, photocurrent density variation, etc. should be supplemented to prove such statement. Suggested references: (1) Nanomaterials2022, 12, 904; (2) Chem. Eng. J.2021, 424, 130444; (3) Nano Res. 2023, 16, 371-376; etc.

 

Response to comment No. 2

 

• The author used the available techniques to characterize the samples, I hope from the reviewer to consider this situation.

 

• The author expected the good charge separation from the observed enhancements in the photocatalytic activity after incorporation of dopants.

 

 

 

3. Line 42-44: Compared to those mentioned here, other more important visible-light driven photocatalyst materials are missing, for example Fe₂O₃, WO₃, g-C₃N₄, etc.

 

Response to comment No. 3

 

• The suggested photocatalyst materials were introduced in the revised manuscript with reference number 5, 16 and 17 (highlighted in the revised manuscript).

…………………………………………………………………………………….

 

4. In view of the physicochemical properties of the doped photocatalysts after the reaction, further structural characterization data of the used catalysts are needed to prove the stability.

 

Response to comment No. 4

 

• The XRD of the best catalyst after the photo-degradation reaction was introduced in the revised manuscript as Figure 15(highlighted in the revised manuscript).

 

 

5. Conclusions section could be more concise.

 

Response to comment No. 5

 

• The conclusions was modified and discussed according to reviewer comment (highlighted in the revised manuscript).

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6- Moderate editing of English language is required.

 

Response to comment No. 6

 

• The English language was modified in the total manuscript (highlighted in the revised manuscript). Hope that the modifications in the level required by the reviewer.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

① "The author used the available techniques to characterize the samples, I hope from the reviewer to consider this situation. The author expected the good charge separation from the observed enhancements in the photocatalytic activity after incorporation of dopants".

- "Enhancements in the photocatalytic activity after incorporation of dopants" doesn't certainly mean "good charge separation". It may only because of the improved light absorbance (Fig. 8). Without any experimental evidence, the so-called "good charge separation" by piezoelectric effect is totally untenable.

 

② Fig. 15: Instead of only showing one curve, the XRD patterns of BaTi_0.96Cu_0.02Nb_0.02O₃ after and before (d in Fig. 1) photocatalytic test should be merged together and compared carefully.

Moderate editing of English language is required.

Author Response

Reviewer 3

 

1- The author used the available techniques to characterize the samples, I hope from the reviewer to consider this situation. The author expected the good charge separation from the observed enhancements in the photocatalytic activity after incorporation of dopants

 

- "Enhancements in the photocatalytic activity after incorporation of dopants" doesn't certainly mean "good charge separation". It may only because of the improved light absorbance (Fig. 8). Without any experimental evidence, the so-called "good charge separation" by piezoelectric effect is totally untenable.

 

 

Response to comment No. 1

 

• Thank you very much for your comments.
• Based on your comment, the author modified the manuscript as follows:

 

• The title was modified to “New BaTi₉₆Cu_0.02X_0.02O₃ (X = V, Nb) photocatalysts for dyes effluent remediation: Broad visible light response”.

 

• With respect to the point of the charge separation, since we haven’t the suitable technique for analysis of this point, the author not confirmed it in the second discussion of revised manuscript.

 

• The discussion of the photocatalytic part was basically related to high absorption of visible light spectrum.

 

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2- Fig. 15: Instead of only showing one curve, the XRD patterns of BaTi_0.96Cu_0.02Nb_0.02O₃ after and before (d in Fig. 1) photocatalytic test should be merged together and compared carefully.

 

 

Response to comment No. 2

 

• The Figure was modified according to reviewer comment in the revised manuscript (highlight in the revised manuscript).

 

Author Response File: Author Response.pdf