Photocatalytic Degradation of Tetracycline Hydrochloride by Mn/g-C3N4/BiPO4 and Ti/g-C3N4/BiPO4 Composites: Reactivity and Mechanism
and Mingyu Li 2,*Round 1
Reviewer 1 Report
The paper entitled “Photocatalytic degradation of tetracycline hydrochloride by Mn/g-C3N4/BiPO4 and Ti/g-C3N4/BiPO4 composite: reactivity and mechanism” , authored by Wei Qian, et al, reports on the synthesis methods of Mn/g-C3N4/BiPO4 and Ti/g-C3N4/BiPO4 composite, characterization like XRD and HRTEM, along with the exploration on the degradation mechanisms to reveal the role they play as photocatalyst. This paper is well structured. Their conclusions are consistently supported by their experimental findings, which are of interest for the readers of Catalysts. It could be accepted as the current format without any changes.
Author Response
The paper entitled “Photocatalytic degradation of tetracycline hydrochloride by Mn/g-C3N4/BiPO4 and Ti/g-C3N4/BiPO4 composite: reactivity and mechanism” , authored byWei Qian, et al, reports on the synthesis methods of Mn/g-C3N4/BiPO4 and Ti/g-C3N4/BiPO4 composite, characterization like XRD and HRTEM, along with the exploration on the degradation mechanisms to reveal the role they play as photocatalyst. This paper is well structured. Their conclusions are consistently supported by their experimental findings, which are of interest for the readers of Catalysts. It could be accepted as the current format without any changes.
Reply to general comments:
Thank you very much for your positive remarks.
Reviewer 2 Report
In this manuscript, the results of this research are conveyed thoughtfully and completely, and they are consistent with the experimental findings. However, the authors failed to explain and draw out the novelty of the work, this aspect needs to be improved. This work is worthwhile to be publish in this journal after major revision. The following issues should be addressed:
1. Introduction is well-organized but the importance and novelty of the research should be highlighted and more clearly stated. The authors should give some examples of works in the bibliography, to clear the advantage of their work in comparison with those works.
2. Maybe the author should compare their results clearly with other reported works, highlighting the advantage and disadvantages.
3. The authors are responsible for the English, which should be polished throughout the manuscript to clear some minor typo/grammar errors.
4. Experimental part. Please indication initial concentration of pollutant. And what is the average concentration of this pollutant in wastewater that should be clean up?
5. Authors did not performed experiments on water purification using real wastewater. It is recommended to performed experiments on real wastewater, since there are many components that can significantly affect both catalytic properties and contaminate the catalyst.
6. Authors should discuss how prepared composites can be used in real experiments. Сan the composite contaminate water, and does it make it dangerous for human consumption. How can the composite be removed from the water after purification?
7. In Introduction part, some relative reports references about using of different oxides in photocatalysis process could help:
https://doi.org/10.1007/s10904-023-02604-0, https://doi.org/10.3390/ma16062170.
Hence, I recommend it accepted for publication after Major revisions.
Comments for author File: 
Comments.pdf
Author Response
Please refer to the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
In this manuscript, the authors synthesized Ti-BPC and Mn-BPC composite materials, characterized them, and evaluated their efficacy for photocatalytic degradation of tetracycline hydrochloride under visible light illumination.
Unfortunately, the quality of the paper is not high enough. The manuscript appears to have been hastily composed, with evident oversights. Notably, there has been a lack of verification of the PDF file. For instance, on line 54, reference 14 is inaccurately attributed to Feng and is not related to the TiO2/g-C3N4/BiPO4 composite. Similarly, reference 15 is incorrectly associated with Li et al. and is unrelated to AgBr/g-C3N4/BiPO4. It is evident that there are several inconsistencies within the reference list. A meticulous review of all references is strongly advised. Additionally, on line 250, there are unreadable characters present in the manuscript.
The manuscript requires significant refinement to reach an acceptable standard. I would like to address some major concerns:
1. It appears that the sorption equilibrium was not attained prior to initiating light exposure in Figure 1, especially for Ti-BPC. This issue also applies to Figure 7. To address this, it is recommended to extend the sorption duration and include more data points in the dark phase before initiating the photoreaction.
2. Line 100 references a crystal spacing of 0.2669, without adequate explanation of its significance. Please provide clarification.
3. In lines 104-106, the detection of g-C3N4, BiPO4, and Bi does not necessarily indicate successful preparation of the ternary composite, given the absence of Mn detection. This should be rectified.
4. The weight percentages of Ti and Mn, as determined by XPS, should be clarified. Do these values align with the nominal percentages specified during the composite synthesis process?
5. Is there tangible evidence, either from XPS or FTIR analyses, demonstrating chemical interactions among TiO2, g-C3N4, and BiPO4? The synthesis must be substantiated as true composite formation, rather than a mere physical mixture.
6. On lines 138-141, please provide an in-depth explanation for how the detection of these carbon bonds supports the notion of chemical interaction between g-C3N4, BiPO4, and Mn ions.
7. Line 152 incorrectly asserts that XRD can determine the morphology of a material; this should be corrected to accurately reflect that SEM or TEM are appropriate for morphology assessment.
8. Optical properties of the composite materials, such as diffusive reflectance-UV characterization and Tauc plot analysis, should be addressed.
9. It is advisable to examine higher dosages for the optimal dose, potentially at 1.5 g/L and 2 g/L, drawing from references for guidance and please cite (e.g., Applied Catalysis B: Environmental 23.2-3 (1999): 143-157, Figure 5, and Environ. Sci. Technol. Lett. 2020, 7, 8, 613–619, Figure S3).
10. Line 222 attributes Ti-BPC's superior reactivity to its surface area; this claim necessitates supporting data, ideally obtained through BET characterization.
11. Given that TiO2 is a semiconductor, while MnCl2 is not, their respective mechanisms should differ. Please refer to and cite relevant literature (e.g., Applied Catalysis B: Environmental 184 (2016): 96-103) for guidance in diagrammatic representation.
Furthermore, some minor concerns should be addressed:
1. Clarify the contradictory statements regarding BiPO4's electron-hole separation rate and electron-hole recombination rate (lines 43 and 47).
2. Correct the assertion on line 254 and 258 that BQ scavenges electrons, as it is a superoxide radical scavenger.
3. Superscript the "+" symbol in line 255.
Minor editing of English language required
Author Response
Please refer to the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Accepted in the present form
Author Response
Reply to general comments:
Thank you very much for your positive remarks. We have thoroughly gone through and revised the manuscript based on the comments/suggestions provided by the reviewer as given below.
Reviewer 3 Report
I would like to express my gratitude for the authors' diligent efforts in revising this manuscript. While many of my concerns have been appropriately addressed, there are still some that require further clarification or revision.
1. The authors have stated that "Prior to the experiment, adsorption experiments were conducted on the composite catalyst, and the results showed that the adsorption equilibrium time was 60 mins." However, this information is not evident from the pre-sorption results depicted in Figure 1 and Figure 7, as the C/C0 ratio continuously decreased without reaching equilibrium. I would recommend that the authors include the adsorption experiment results in the Supplemental Materials for clarification.
2. While responding to my 8th comment, the authors referred to additional discussion included in the revised manuscript, pointing to "page 2, lines 4-5." However, it appears that the Supplemental Materials are absent from the submission.
3. The authors have not adequately addressed my comment #11. Considering that TiO2 is a semiconductor while MnCl2 is not, their respective mechanisms should differ when combined with g-C3N4/BiPO4. With TiO2, it forms a ternary heterojunction, and its band diagram should resemble the one presented in this paper (Applied Catalysis B: Environmental 184, 96-103, 2016). However, Figure 10 does not seem to represent this adequately but appears to represent a MnCl2-containing material instead. Consequently, I recommend that two distinct schemes be included in Figure 10 to illustrate TiO2-containing and MnCl2-containing materials separately.
Author Response
Please refer to the attachment.
Author Response File: Author Response.pdf
