Degradation of Organic Dye Congo Red by Heterogeneous Solar Photocatalysis with Bi₂S₃, Bi₂S₃/TiO₂, and Bi₂S₃/ZnO Thin Films

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article demonstrates an increase in the efficiency of photodegradation of Congo red dye using natural solar radiation due to the use of Bi2S3/ZnO and Bi2S3/TiO2 heterostructured photocatalysts. The article presents some interesting new results. However, there are a number of principled issues that require correction:

11)     The formed Bi2S3/ZnO and Bi2S3/TiO2 materials have not been characterized convincingly enough. Figs. 2 (a,b), 6 (a,b) and 10 (a,b) do not show any visible differences in materials. The determination of the amount of components of TiO2 and ZnO films by EDX (Figs. 6(c,d) and 10 (c,d)) is at the limit of sensitivity of this method. The presence of TiO2 and ZnO phases in the X-ray diffraction patterns (Figs. 7 and 11) is also at the limit of sensitivity of this method. In this regard, for more complete substantiation it is necessary to add studies using method specializing in surface investigation, such as AES, XPS, Electronography or TEM.

22)    What are the thicknesses of the formed Bi2S3, TiO2 and ZnO thin films? This important information is missing from the article.

33)    The optical studies of Bi2S3/ZnO and Bi2S3/TiO2 thin films show contradictory results. The band gap (Eg) of bulk ZnO is 3.4 eV, Eg of TiO2(anatase) is 3.2 eV. It is logical that modification of Bi2S3 with wider-bandgap ZnO shifts the absorption edge of the Bi2S3/ZnO material more towards blue compared to Bi2S3/TiO2. It is also logical, taking into account the optical studies of the original 2Bi2S3 (Eg=1.9 eV) and 3Bi2S3 (Eg=1.95 eV), that in the series 2Bi2S3/TiO2 and 3Bi2S3/TiO2 the absorption edge shifts towards blue. Why in the same situation in the series 2Bi2S3/ZnO and 3Bi2S3/ZnO there is a shift towards the red? This is not clear. This result requires re-examination or explanation.

44)    There is also a lack of optical studies of TiO2 thin film and ZnO thin film separately.

55)    The authors presented the results of the Congo red degradation studies separately on Bi2S3, but did not present them separately on TiO2 and ZnO. These studies would provide a complete picture of the advantages of using the heterostructured form of Bi2S3/ZnO and Bi2S3/TiO2 photocatalysts.

Author Response

Reviewer 1

Response to referees for Ms. Ref. No.:  catalysts-3156998

First of all, we would like to thank the Editori and the reviewers for all their comments and suggestions on the paper. We have corrected and completed the paper to address their comments and suggestions.

Response to reviewer #1

Comments and Suggestions for Authors

The article demonstrates an increase in the efficiency of photodegradation of Congo red dye using natural solar radiation due to the use of Bi2S3/ZnO and Bi2S3/TiO2 heterostructured photocatalysts. The article presents some interesting new results. However, there are a number of principled issues that require correction:

1. The formed Bi2S3/ZnO and Bi2S3/TiO2 materials have not been characterized convincingly enough.

A) Figs. 2 (a,b), 6 (a,b) and 10 (a,b) do not show any visible differences in materials.

R. Thanks for the observation, there was a mistake. I apologize for the error.

The figures 2 (A) and (B) were change for the correct material for 2 layers Bi2S3 and 3 layers Bi2S3. We have mentioned that the crystal growth is observed when the number of CBD increase.

“In Figure 2B, crystal growth is observed compared to Figure 2A due to the third layer of the chemical bath. The methodology followed by Carrillo and collaborators [39] was entirely reproducible, resulting in the same morphology.”

B) The determination of the amount of components of TiO2 and ZnO films by EDX (Figs. 6(c,d) and 10 (c,d)) is at the limit of sensitivity of this method.

Although we are at the limits of detection of the EDX analysis we have added supplementary material mapping the constituent elements of the samples by EDX. These can be seen in figures FS2, FS3, FS5 and FS6 where the presence of homogeneously distributed elements of Bi, S, O, Ti or Zn is demonstrated. The description in the manuscript was mentioned in the manuscript as follows:

“Also, it is observed by means of EDAX analysis shown in Fig. S2 and Fig. S3, where the elemental distribution of Bi, S, Ti and O is homogeneous.”

“Additionality is observed by means of EDAX analysis shown in Fig. S5 and Fig. S6, where the elemental distribution of Bi, S, Zn and O is homogeneous.

C) The presence of TiO2 and ZnO phases in the X-ray diffraction patterns (Figs. 7 and 11) is also at the limit of sensitivity of this method.

The TiO₂ and ZnO phases in the X-ray diffraction patterns have already been reported in [47] and [67]. To clarify how to obtain these, we have added a short description in the corresponding sections:

“Figure 7 show distinct intensity peaks in the diffractograms indicating characteristic orientations of the TiO₂ nanoparticles. The (1 0 1) orientation corresponds to the anatase phase and according to the TiO₂ NpS reported in [47].”

“Characteristic peaks in the crystallographic planes (1 0 1) and (1 0 0) are shown for ZnO, corresponding to the hexagonal wurtzite crystal structure [51] and according to the ZnO NpS reported in [67] .”

D) In this regard, for more complete substantiation it is necessary to add studies using method specializing in surface investigation, such as AES, XPS, Electronography or TEM.

Thank you for your suggestion. Now we do not have access to rapid analyses to make more characterizations. Definitely, these will be done in the future.

22)    What are the thicknesses of the formed Bi2S3, TiO2 and ZnO thin films? This important information is missing from the article.

R. We have not measured the thickness of the materials, but each material changes the absorbance or transmittance, and we can relate this with the thickness, this is demonstrated with optical characterization absorbance or transmittance UVVIS spectra, we add in Supplementary Material Transmittance UVVis spectra:

“Transmittance spectra can be seen in FS1. “

“Transmittance spectra can be seen in FS4. “

“Transmittance spectra can be seen in FS7. “

 

33)    The optical studies of Bi2S3/ZnO and Bi2S3/TiO2 thin films show contradictory results. The band gap (Eg) of bulk ZnO is 3.4 eV, Eg of TiO2 (anatase) is 3.2 eV. It is logical that modification of Bi2S3 with wider-bandgap ZnO shifts the absorption edge of the Bi2S3/ZnO material more towards blue compared to Bi2S3/TiO2. It is also logical, taking into account the optical studies of the original 2Bi2S3 (Eg=1.9 eV) and 3Bi2S3 (Eg=1.95 eV), that in the series 2Bi2S3/TiO2 and 3Bi2S3/TiO2 the absorption edge shifts towards blue. Why in the same situation in the series 2Bi2S3/ZnO and 3Bi2S3/ZnO there is a shift towards the red? This is not clear. This result requires re-examination or explanation.

R. We have added more information to give response to reviewer:

“The absorption edges of the thin films 2 layers Bi₂S₃/ZnO range from 700 nm to 450 nm. A blue shift, indicating a shift towards shorter wavelengths, was observed compared to Bi₂S₃ thin films without ZnO. Additionally, the 3-layer Bi₂S₃/ZnO films showed a red shift towards the visible region [53]. The addition of ZnO resulted in enhanced absorption in the visible region, because absorbs a small part of visible light near 400 nm, but it is not enough because It is the limit in the region UV and visible, so a material towards the visible region is required to take advantage of the source of solar radiation [54], this one reason that is expanding the photocatalytic activity of Bi₂S₃ thin films. Transmittance spectra can be seen in FS7.

The addition of ZnO enhances the photocatalytic activity of Bi₂S₃ thin films in the ultraviolet-visible spectrum so that the range of OH radical formation is broader. Hence, sunlight becomes a viable radiation source, falling within the range of 450 to 700 nm [55]. Thus, photons with energies greater than those depicted in Figure 12 (2.45 eV and 2.0 eV) can induce radical formation, leading to pollutant reduction. The bandgap increases significantly when ZnO is added to Bi₂S₃ thin films as the metal oxide exhibits a bandgap of 3.3 eV [56]. AL-Zahrani has different bang gaps of Bi₂S₃/ZnO, where the cationic concentration (amount of positive charges present on the surfaces of materials) provoke the band gap energy blue shift, in this case has a heterostructure with anionic concentration because the materials are type n therefore has shift towards the red [54].”

References:

[53] AL-Zahrani, A.A.; Zainal, Z.; Talib, Z.A.; Lim, H.N.; Holi, A.M. Bismuth sulphide

decorated ZnO nanorods heterostructure assembly via controlled SILAR cationic

concentration for enhanced photoelectrochemical cells. Mater. Res. Express 2020, 7,

doi:10.1088/2053-1591/ab6e2e.

[54] Qi, K.; Cheng, B.; Yu, J.; Ho, W. Review on the improvement of the photocatalytic

and antibacterial activities of ZnO. J. Alloys Compd. 2017, 727, 792–820.

[55] Borges, M.E.; Sierra, M.; Méndez-Ramos, J.; Acosta-Mora, P.; Ruiz-Morales, J.C.;

Esparza, P. Solar degradation of contaminants in water: TiO2 solar photocatalysis

assisted by up-conversion luminescent materials. Sol. Energy Mater. Sol. Cells 2016,

155, 194–201, doi:10.1016/j.solmat.2016.06.010.

[56] Nikam, P.R.; Baviskar, P.K.; Sali, J. V.; Gurav, K. V.; Kim, J.H.; Sankapal, B.R. SILAR coated Bi2S3 nanoparticles on vertically aligned ZnO nanorods: Synthesis and characterizations. Ceram. Int. 2015, 41, 10394–10399, doi:10.1016/j.ceramint.2015.03.239.

44)    There is also a lack of optical studies of TiO2 thin film and ZnO thin film separately.

R. As we have mentioned previously, the TiO₂ and ZnO materials used in this research have already been reported in [47] and [57], in addition we have added more description:

“The absorption spectrum of the 2-layer Bi₂S₃/TiO₂ exhibits a blue shift about the 3-layer Bi₂S₃/TiO₂ thin film, enabling excitation with longer wavelengths in the visible region, associated with electro-hole pair generation [54]. Transmittance spectra can be seen in FS4.

The TiO₂ induce shifts toward to UV region due exhibits an absorption edge in 400 nm [29]. “

References

[54] Peng, S.; Huang, Y.; Li, Y. Rare earth doped TiO2-CdS and TiO2-CdS composites

with improvement of photocatalytic hydrogen evolution under visible light irradiation.

Mater. Sci. Semicond. Process. 2013, 16, 62–69, doi:10.1016/j.mssp.2012.06.019.

[29] Qi, K.; Cheng, B.; Yu, J.; Ho, W. Review on the improvement of the photocatalytic

and antibacterial activities of ZnO. J. Alloys Compd. 2017, 727, 792–820.

55)    The authors presented the results of the Congo red degradation studies separately on Bi2S3, but did not present them separately on TiO2 and ZnO. These studies would provide a complete picture of the advantages of using the heterostructured form of Bi2S3/ZnO and Bi2S3/TiO2 photocatalysts.

R. We have expanded the discussions in section 2.2.3 and 2.3.3 giving more detail about what was requested

“2.2.3. Optical characterization of Bi₂S₃/TiO₂ thin films

The absorption spectrum of the 2-layer Bi₂S₃/TiO₂ exhibits a blue shift about the 3-layer Bi₂S₃/TiO₂ thin film, enabling excitation with longer wavelengths in the visible region, associated with electro-hole pair generation [54]. Transmittance spectra can be seen in FS4.

The TiO₂ induce shifts toward to UV region due exhibits an absorption edge in 400 nm [29]. “

Both heterostructures can initiate the REDOX process of pollutants due to strong absorption in the visible region [48].

“2.3.3. Optical characterization of Bi₂S₃/ZnO thin films

The absorption edges of the thin films 2 layers Bi₂S₃/ZnO range from 700 nm to 450 nm. A blue shift, indicating a shift towards shorter wavelengths, was observed compared to Bi₂S₃ thin films without ZnO. Additionally, the 3-layer Bi₂S₃/ZnO films showed a red shift towards the visible region [53]. The addition of ZnO resulted in enhanced absorption in the visible region, because absorbs a small part of visible light near 400 nm, but it is not enough because It is the limit in the region UV and visible, so a material towards the visible region is required to take advantage of the source of solar radiation [54], this one reason that is expanding the photocatalytic activity of Bi₂S₃ thin films. Transmittance spectra can be seen in FS7.  

The addition of ZnO enhances the photocatalytic activity of Bi₂S₃ thin films in the ultraviolet-visible spectrum so that the range of OH radical formation is broader. Hence, sunlight becomes a viable radiation source, falling within the range of 450 to 700 nm [55]. Thus, photons with energies greater than those depicted in Figure 12 (2.45 eV and 2.0 eV) can induce radical formation, leading to pollutant reduction. The bandgap increases significantly when ZnO is added to Bi₂S₃ thin films as the metal oxide exhibits a bandgap of 3.3 eV [56]. AL-Zahrani has different bang gaps of Bi₂S₃/ZnO, where the cationic concentration (amount of positive charges present on the surfaces of materials) provoke the band gap energy blue shift, in this case has a heterostructure with anionic concentration because the materials are type n therefore has shift towards the red [54].”

References

[29] Qi, K.; Cheng, B.; Yu, J.; Ho, W. Review on the improvement of the photocatalytic

and antibacterial activities of ZnO. J. Alloys Compd. 2017, 727, 792–820.

 

[53] AL-Zahrani, A.A.; Zainal, Z.; Talib, Z.A.; Lim, H.N.; Holi, A.M. Bismuth sulphide

decorated ZnO nanorods heterostructure assembly via controlled SILAR cationic

concentration for enhanced photoelectrochemical cells. Mater. Res. Express 2020, 7,

doi:10.1088/2053-1591/ab6e2e.

 

[54] Peng, S.; Huang, Y.; Li, Y. Rare earth doped TiO2-CdS and TiO2-CdS composites

with improvement of photocatalytic hydrogen evolution under visible light irradiation.

Mater. Sci. Semicond. Process. 2013, 16, 62–69, doi:10.1016/j.mssp.2012.06.019.

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In this research, a series of Bi₂S₃-based heterogeneous photocatalysts, specifically Bi₂S₃/TiO₂ and Bi₂S₃/ZnO, were developed to enhance the photocatalytic efficiency of pure Bi₂S₃ in degrading Congo red. While the physicochemical characteristics and degradation performance of the synthesized samples have been thoroughly examined, the manuscript lacks logical organization and contains numerous evident errors. In summary, I believe this article requires significant revisions before it can be deemed suitable for publication in the journal "Catalysts."

1. The number of Figures in this article is excessive. To facilitate easier comparison among the various materials (Bi₂S₃, Bi₂S₃/TiO₂, and Bi₂S₃/ZnO), it is recommended to consolidate their SEM images, XRD patterns, contact angles, and DRS spectra into a single figure for each category. This approach would help keep the total figure count below 8. Furthermore, the related discussions should be streamlined to create a more concise paragraph.

2. Certain errors need to be addressed. For instance, the SEM images of Bi₂S₃ and Bi₂S₃/ZnO depicted in Figures 2 and 10 appear to be identical. Additionally, the label for the contact angle of Bi₂S₃/TiO₂ in Figure 9 does not correspond correctly with the accompanying images. Furthermore, there are issues with superscripts and subscripts related to Bi₂S₃ found in Lines 101, 320, and 321, among others.

3. In addition to the band gap value, the positions of the conduction band and valence band are essential indicators for photocatalysts, as they influence the redox potential. To determine the values of E_CB and E_VB, it is recommended to cite several important references. Additionally, the revised manuscript includes a detailed explanation to ensure the precise locations of CB and VB are clearly defined.

[1] F. Ye, J. Qian, J.J. Xia, L.F. Li, S.J. Wang, Z.X. Zeng, J. Mao, M. Ahamad, Z.R. Xiao, Q.R. Zhang, Efficient photoelectrocatalytic degradation of pollutants over hydrophobic carbon felt loaded with Fe-doped porous carbon nitride via direct activation of molecular oxygen, Environ Res, 249 (2024), 118497.

[2] P.L. Wang, S.Y. Fan, X.Y. Li, J. Duan, D.K. Zhang, Modulating the molecular structure of graphitic carbon nitride for identifying the impact of the piezoelectric effect on photocatalytic H₂O₂ production, ACS Catalysis, 2023, 13, 9515-9523.

4. In Figure 14, the author highlights that the 2 Bi₂S₃/ZnO film demonstrates superior efficiency in degrading Congo Red compared to other samples. However, the overall degradation rate is capped at just 21.93% within 30 minutes. This raises the question of why the author does not evaluate their performance over a longer duration, once the pollutants can be completely decomposed.

5. In order to showcase the complete elimination of pollutants, it is essential to present the total organic carbon (TOC) removal data for Bi₂S₃-based materials.

Comments on the Quality of English Language

Moderate editing of English language required

Author Response

 

Reviewer 2

Response to referees for Ms. Ref. No.:  catalysts-3156998

First of all, we would like to thank the Editori and the reviewers for all their comments and suggestions on the paper. We have corrected and completed the paper to address their comments and suggestions.

Response to reviewer #2

Comments and Suggestions for Authors

1. The number of Figures in this article is excessive. To facilitate easier comparison among the various materials (Bi₂S₃, Bi₂S₃/TiO₂, and Bi₂S₃/ZnO), it is recommended to consolidate their SEM images, XRD patterns, contact angles, and DRS spectra into a single Figure for each category. This approach would help keep the total Figure count below 8. Furthermore, the related discussions should be streamlined to create a more concise paragraph.

R. Thanks for your observation, Figures 3, 4, 7, 8,11, and 12 were edited, where each Figure contains the same material differentiating them in layers in the bismuth sulfide. Figure 15 was edited by joining the graph of absorbances of Congo red concentrations and the degradation kinetics concerning time.

The Figures edited were the XRD (X-ray diffraction), where the intensity of the peaks is higher for the three-layer bismuth sulfide than that of the two-layer bismuth sulfide, Figures 3 (A) and 3 (B) are joined into a single Figure, becoming only Figure 3, the Figure 3 is appreciating better the comparison in each material indicating the crystalline phases of each of the materials.

We have added description:

“Fig. 3 displays various diffraction patterns where the characteristic peak of the Bi₂S₃ thin films appears on the crystallographic plane (2 2 1), corresponding to the orthorhombic structure”

 

The Figure 4 (A) and 4 (B) are joined into a single Figure, becoming only Figure 4.

We have added description:

“The absorption spectra in Figure 4 show a shift to the right (red shift) as the number of layers increases from 2 to 3. Also, in the range of 750nm to 550 nm”

“Regarding the band gap energy, Tauc's method (see Figure 4) [42] was used and reported values of 1.9 eV and 1.95 eV were obtained.”

The Figure 7 (A) and 7 (B) are joined into a single Figure, becoming only Figure 7.

The Figure 8 (A) and 8 (B) are joined into a single Figure, becoming only Figure 8.

We have added description:

“The absorption spectrum of the 2-layer Bi₂S₃/TiO₂ exhibits a blue shift about the 3-layer Bi₂S₃/TiO₂ thin film, Figure 8,”

“Figure 8 show the bandgaps obtained using Tauc's method for the two-layer and three-layer of Bi₂S₃/TiO₂ films, resulting in 2.3 eV and 2.35 eV, respectively”

The Figure 11 (A) and 11 (B) are joined into a single Figure, becoming only Figure 11.

We have added description:

“Figure 11 display the diffractogram peaks of the material separately, as it is con-sidered a heterojunction, where the ZnO is deposited by spin-coating and neither ma-terial is structurally modified.”

The Figure 12 (A) and 12 (B) are joined into a single Figure, becoming only Figure 12.

We have added description:

“The absorption edges of the thin films 2 and 3 layers Bi₂S₃/ZnO range from 750 nm to 450 nm (see Figure 12).”

“Thus, photons with energies greater than those depicted in Figure 12 (2.45 eV and 2.0 eV) can induce radical formation, leading to pollutant reduction”

The Figure 15 (A) and 15 (B) are joined into a single Figure, becoming only Figure 15.

We have added description:

“In Figure 15 show the absorbance related to organic contaminant degradation reveals a primary absorption edge at 497 nm”

“And in Figure 15 show, the degradation time of the highest efficiency was calculated, showing the degradation kinetics of the organic pollutant”

2. Certain errors need to be addressed. For instance, A) the SEM images of Bi₂S₃and Bi₂S₃/ZnO depicted in Figures 2 and 10 appear to be identical. B) Additionally, the label for the contact angle of Bi₂S₃/TiO₂ in Figure 9 does not correspond correctly with the accompanying images.  C) Furthermore, there are issues with superscripts and subscripts related to Bi₂S₃ found in Lines 101, 320, and 321, among others.

R. A) Exactly the images are the same. There was a mistake. I apologize for the error. The Figure 2 was changed by the correct micrograph. We have mentioned that the crystal growth is observed when the number of CBD increase. So add the image correct in the text.

B) To clarify the description the description was changed according to the Figure 9 (A) and 9 (B).

“The contact angle of the 2-layer and 3-layer thin films (Figures 9 and B) show a contact angle of 95.3⁰ to 86.0⁰ respectively”

C) The subscript of Bi₂S₃was corrected.

3. In addition to the band gap value, the positions of the conduction band and valence band are essential indicators for photocatalysts, as they influence the redox potential. To determine the values of E_CBand E_VB, it is recommended to cite several important references. Additionally, the revised manuscript includes a detailed explanation to ensure the precise locations of CB and VB are clearly defined.

[1] F. Ye, J. Qian, J.J. Xia, L.F. Li, S.J. Wang, Z.X. Zeng, J. Mao, M. Ahamad, Z.R. Xiao, Q.R. Zhang, Efficient photoelectrocatalytic degradation of pollutants over hydrophobic carbon felt loaded with Fe-doped porous carbon nitride via direct activation of molecular oxygen, Environ Res, 249 (2024), 118497.

[2] P.L. Wang, S.Y. Fan, X.Y. Li, J. Duan, D.K. Zhang, Modulating the molecular structure of graphitic carbon nitride for identifying the impact of the piezoelectric effect on photocatalytic H₂O₂ production, ACS Catalysis, 2023, 13, 9515-9523.

R. The methodology band gap is used the constant Planck is associated to mayor edge absorption with wavelength of the material in study, therefore we use Tauc's method, the articles that you recommended use the photoelectrochemical measurements, we don’t have the equipment in this moment to do measurements. The bandgap determined in our research is consistent with what others have reported. We have mentioned this in the corresponding sections.

4. In Figure 14, the author highlights that the 2 Bi₂S₃/ZnO film demonstrates superior efficiency in degrading Congo Red compared to other samples. However, the overall degradation rate is capped at just 21.93% within 30 minutes. This raises the question of why the author does not evaluate their performance over a longer duration, once the pollutants can be completely decomposed.

R. It starts with an initial concentration of 20.011 mg/L after 30 minutes of exposure to solar irradiation decreases the concentration to 15.727 mg/L,15.904 mg/L, 13.846 mg/L, 15.237 mg/L, 15.460 mg/L, 15.691 mg/L for the 2Bi₂S₃, 3 Bi₂S₃, 2 Bi₂S₃/ZnO, 3 Bi₂S₃/ZnO, 2 Bi₂S₃/TiO₂ and 3 Bi₂S₃/TiO₂ respectively, hence giving a minor concentration gives variables for Equation 1 ( ). Obtaining the variables can do the kinetic degradation for any time.

The description for this in the text is as follows

“And in Figure 15 show, the degradation time of the highest efficiency was calculated, showing the degradation kinetics of the organic pollutant. The 2 Bi₂S₃/ZnO material degrades 100% at 300 min, according to the solution of equation 1 as a first-order integral, deriving equation 1:”

  eq 1.

5. In order to showcase the complete elimination of pollutants, it is essential to present the total organic carbon (TOC) removal data for Bi₂S₃-based materials.

R. Thank you for your suggestion but we don’t have the equipment in this moment to do measurements. But, the absorption spectrum of a solution of Congo red concentration demonstrates that decreasing or transforming the organic pollutant. In the Figure 15 and table 1 show concentrations after photocatalysis.

The description for this in the text is as follows:

“Table 1 shows the summary of each of the replicas of the photocatalytic activity exposed for 30 minutes with each of the different materials”

“In Figure 15 show the absorbance related to organic contaminant degradation reveals a primary absorption edge at 497 nm. As the organic molecule transforms and its concentration decreases, this edge diminishes. Notably, the absorbance edges show a decreasing trend, characterized by a π → π * electronic transition with a bathochromic shift (red shift), indicating absorption at longer wavelengths”

“And in Figure 15 show, the degradation time of the highest efficiency was calculated, showing the degradation kinetics of the organic pollutant.”

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

On the whole, the authors responded to the comments and made changes to the article to take them into account. 

Author Response

Reviewer 1

Response to referees for Ms. Ref. No.:  catalysts-3156998

First of all, we would like to thank the Editori and the reviewers for all their comments and suggestions on the paper. We have corrected and completed the paper to address their comments and suggestions.

Response to reviewer #1

Comments and Suggestions for Authors

1. On the whole, the authors responded to the comments and made changes to the article to take them into account.

R. Thank you for your revision.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In the initial round of revisions, many questions were effectively addressed. However, a few issues remain unresolved. For instance, it is recommended to consolidate the Tauc plots of 2 Bi₂S₃ and 3 Bi₂S₃ from the revised Figure 4, as well as those of 2 Bi₂S₃/TiO₂ and 3 Bi₂S₃/TiO₂ in the revised Figure 8, and 2 Bi₂S₃/ZnO and 3 Bi₂S₃/ZnO in the revised Figure 12 into a single figure as the insert picture. Once this issue is resolved, it may be deemed suitable for publication in the journal "Catalysts."

Comments on the Quality of English Language

Minor editing of English language required.

Author Response

Reviewer 2

Response to referees for Ms. Ref. No.:  catalysts-3156998

First of all, we would like to thank the Editori and the reviewers for all their comments and suggestions on the paper. We have corrected and completed the paper to address their comments and suggestions.

Response to reviewer #2

Comments and Suggestions for Authors

1. In the initial round of revisions, many questions were effectively addressed. However, a few issues remain unresolved. For instance, it is recommended to consolidate the Tauc plots of 2 Bi₂S₃and 3 Bi₂S₃from the revised Figure 4, as well as those of 2 Bi₂S₃/TiO₂ and 3 Bi₂S₃/TiO₂ in the revised Figure 8, and 2 Bi₂S₃/ZnO and 3 Bi₂S₃/ZnO in the revised Figure 12 into a single figure as the insert picture. Once this issue is resolved, it may be deemed suitable for publication in the journal "Catalysts."

R. Thanks for your observation, the mentioned graphs have been consolidated:

2. Minor editing of English language required.

R. The manuscript has been revised.

Author Response File: Author Response.pdf