Facile Aqueous-Phase Synthesis of Stabilizer-Free Photocatalytic Nanoparticles
Round 1
Reviewer 1 Report
The author synthesized disk-shaped BiOCl using a simple hydrolysis method and compared the catalytic reactions with or without polymer capping. However, since this paper's originality is unclear, and judged that the comparison group had not properly selected, the reject decision is made. (Resubmission is worth considering).
1) synthesis method is not original. Authors should not focus their original point on this. (Recent advances of bismuth oxychloride photocatalytic material: Property, preparation and performance enhancement, Journal of Electronic Science and Technology Volume 18, Issue 2, June 2020, 100020)
2) The counter group setting is wrong. Adding a stabilizer to the synthesized BiOCl is meaningless. Since BiOCl is already agglomerated, it is difficult to exhibit a dispersion effect as an additive under this condition. Therefore, an in-situ modification for BiOCl is recommended. Or in the case of ex-situ modification, the catalytic reaction should be conducted after removing the additives, which is suitable for the original purpose.
3) It is better to remove the contents controlling BiOCl thickness by changing the precursor concentration and Br doping on BiOCl because they are out of the overall flow.
Author Response
Reviewer#1
Comment 1. Synthesis method is not original. Authors should not focus their original point on this. (Recent advances of bismuth oxychloride photocatalytic material: Property, preparation and performance enhancement, Journal of Electronic Science and Technology Volume 18, Issue 2, June 2020, 100020)
Response 1. We appreciate for the valuable comments of the reviewer which can improve our paper. In addition to the papers mentioned by reviewer, we have compared our synthesis with previous reported method. We found the following 5 papers using a method similar to ours.
1) Study of the electronic structure and photocatalytic activity of the BiOCl photocatalyst. Applied Catalysis B: Environmental 68 (2006) 125–129
2) Hydrolytic synthesis of flower like BiOCl and its photocatalytic performance under visible light. Materials Letters 108(2013)168–171
3) Facile synthesis of BiOCl nano-flowers of narrow band gap and their visible-light-induced photocatalytic property. Catalysis Communications 23 (2012) 54–57
4) Bismuth oxychloride nanoflakes: Interplay between composition-structure and optical properties. Dalton Trans., 41 (2012), 5480
5) Well-defined BiOCl colloidal ultrathin nanosheets: synthesis, characterization, and application in photocatalytic aerobic oxidation of secondary amines. Chem. Sci., 2015, 6, 1873)
They adjusted the pH of the solution to control the reactivity or added additional surfactant to form nanoparticles. On the other hand, in our method, there is no pH control or additional surfactant input. We think this is both the strength and the difference of our synthetic method.
We have added this information to the revised manuscript (Please refer line 62-63 in page 2 and ref 25-29).
Comment 2. The counter group setting is wrong. Adding a stabilizer to the synthesized BiOCl is meaningless. Since BiOCl is already agglomerated, it is difficult to exhibit a dispersion effect as an additive under this condition. Therefore, an in-situ modification for BiOCl is recommended. Or in the case of ex-situ modification, the catalytic reaction should be conducted after removing the additives, which is suitable for the original purpose.
Response 2. We would like thank to this suggestion. As pointed out by reviewer, the surface modification method we used has the effect of altering the dispersion of nanoparticles. Actually, the dispersity of the surfactant-free BiOCl nanoparticles in aqueous solution was the worst. What we considered most important in this experiment was how the reactivity changes when the surfaces of nanoparticles of the same shape and size are different. If PVP or PEI is added in the middle of manufacturing BiOCl nanoparticles, the size and shape of the manufactured nanoparticles change. Actually the surfactant-free BiOCl nanoparticles showed high reactivity despite poor dispersity. We think that this result shows the influence of surfactant in the catalytic reaction well.
Comment 3. It is better to remove the contents controlling BiOCl thickness by changing the precursor concentration and Br doping on BiOCl because they are out of the overall flow.
Response 3. We appreciate for the valuable comments of the reviewer which can improve our paper. We have removed them in the revised manuscript.
Reviewer 2 Report
Authores reported a study on BiOCl in photodegradation of a pigment such as methylene blue.
Firstly, How the synthesis proposed is better than the one proopsed by Li et al.(Li, Y., Liu, J., Jiang, J., & Yu, J. (2011). UV-resistant superhydrophobic BiOCl nanoflake film by a room-temperature hydrolysis process. Dalton Transactions, 40(25), 6632-6634)
In figure 1D, XRD spectrum of synthesized BiOCl seemd to poorly match the BiOCl reference. Which is tjeir similarity?
How did you dertimine the synthesized BiOCl composition? XPS fit must be included in the manuscript e discussed. Reporting just the singnals in the supporting informations is not sufficent.
Concerning photodegradation experiments, data are reported without error bar. In this way they are meaningless. Errors must be added and results must be compared with statistical tools such as t-test.
Additionally, Authors did not evaluate the effect of adsorption on BiOCl surface in teh methylene blue rmoval. It should be studied.
Considering the points raised above, i recommand major revisions for this paper.
Author Response
Comment 1. Firstly, How the synthesis proposed is better than the one proposed by Li et al.(Li, Y., Liu, J., Jiang, J., & Yu, J. (2011). UV-resistant superhydrophobic BiOCl nanoflake film by a room-temperature hydrolysis process. Dalton Transactions, 40(25), 6632-6634)
Response 1. We would like thank to your comment. Compared with a commented report, our method is conducted in an aqueous-phase without a supporting material such as a foil. So, we think that our synthetic method is more advantageous in terms of mass production.
Comment 2. In figure 1D, XRD spectrum of synthesized BiOCl seemed to poorly match the BiOCl reference. Which is their similarity?
Response 2. The main peaks of the BiOCl nanoplates were well matched with a previously report (Zhang, X.; Wang, L.W.; Wang, C.Y.; Wang, W.K.; Chen, Y. L.; Huang, Y. X.; Li, W. W.; Feng, Y. J.; Yu, H. Q. Synthesis of BiOClxBr1−x Nanoplate Solid Solutions as a Robust Photocatalyst with Tunable Band Structure. Chem. Eur. J. 2015, 21, 11872-11877). We believe that the intensity of the XRD peak is different due to the plate-shape shape of the nanoparticles.
Comment 3. How did you determine the synthesized BiOCl composition? XPS fit must be included in the manuscript e discussed. Reporting just the signals in the supporting information is not sufficient.
Respond 3. We appreciate for the valuable comments of the reviewer which can improve our paper. By deconvolution of the obtained XPS peak, the elemental composition ratio of BiOCl could be known through calculation. We have revised XPS data in the supporting information. In addition, we have added XPS peaks for Br doped BiOCl to Supporting information (Please refer Figure S1 and Figure S5).
Comment 4. Concerning photodegradation experiments, data are reported without error bar. In this way they are meaningless. Errors must be added and results must be compared with statistical tools such as t-test.
Respond 4. We appreciate for the valuable comments of the reviewer which can improve our paper. We have added errors bars to the revised manuscript (Please refer Figure 3 and Figure 6.).
Comment 5. Additionally, Authors did not evaluate the effect of adsorption on BiOCl surface in the methylene blue removal. It should be studied.
Respond 5. In a photocatalytic performance experiment, the catalysts are stirred in the darkness for the first 30 min. It is conducted until adsorption and desorption equilibrium is reached. This is to investigate the absorption performance of the catalyst. Photocatalyst performance can be obtained by measuring the amount of target material removed by irradiating light after the particle is de-absorbed equilibrium. Therefore, we think the effect of absorption of the catalyst can be seen from the initial 30 min experiment.
Round 2
Reviewer 1 Report
The authors mentioned to remove 'dopping' effect, but Figure 6 still shows that contents. please correct this point.
Author Response
Reviewer#1
Comment 1. The authors mentioned to remove 'dopping' effect, but Figure 6 still shows that contents. please correct this point.
Response 1. We appreciate for the valuable comments of the reviewer which can improve our paper. We have removed them in the revised manuscript.
Reviewer 2 Report
Authors answers are adequate.
Author Response
Thank you.
