Water Oxidation over Au-Pd/TiO₂ as a Substitute for Iridium-Based Catalysts

Round 1

Reviewer 1 Report

In present study the O2 evolution reactions performed over Au-Pd/TiO2 catalysts with different composition to compare it with those of IrO2/TiO2 and IrO2/CeO2 heterogeneous catalysts using cerium ammonium nitrate (CAN). The article is devoted to the current topic of obtaining oxygen for the needs of green energy. However, a number of comments should be taken into account before publishing the article.

Among the methods for studying the structure, there is no XRD analysis, which is the standard for such materials; the work presents XRD only for TiO2. It is necessary to provide XRD data for all obtained Au-Pd based catalysts.

Previously, the authors showed that “IrO2 was found to form small clusters of less than 1 nm in size highly dispersed on the oxide support”, what is the state of Au-Pd on the surface of the support, is it an alloy or two separate phases, what is the size of the metal particles? Perhaps a TEM study would provide additional information about the structure of the material.

Figure 9 presents experimental data that does not fit well into a linear relationship, however, such dependencies are shown.

Some graphs need to be moved to supplementary materials to make the article easier to read.

Author Response

Dear Reviewer, please see attached.

Kind regards.

Hicham

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments to the Authors

In this work, the authors synthesized Au-Pd based catalysts deposited on TiO₂ to achieve efficient water oxidation catalysis. The results seem interesting, however, poor figure quality makes reading more difficult. In addition, I also found some potential issues should be addressed. Details are as follows.

1. As we all known, both Pd and Au are the noble metals, which have shown high cost. Why did the authors choose these two metals as substitute catalysts for Ir-based materials. The reason should be clarified.

2. The fine structures of catalysts should be provided, such as morphology and phase structures.

3. The XPS should be deconvolved to reveal the chemical states of catalysts.

4. The mass activities of various catalysts should be included, especially for the precious metal-based catalysts.

5. The quality of figures should be improved, otherwise we cannot obtain enough information about the main conclusions of this manuscript.

Author Response

Dear Reviewer, please see attached.

Kind regards.

Hicham

Author Response File: Author Response.pdf

Reviewer 3 Report

catalysts-2827734

Comments
The article reports the rational synthesis of Au-Pd/TiO2 with various ratios via the deposition precipitation method for the oxygen evolution reaction. The as-synthesized materials were analyzed using XPS and XRD, along with the catalytic measurements. The article could be accepted after addressing the following comments:

1. It is recommended that the authosr check the information for authors to adjust the manuscript according to the journal template.
2. The authors should rewrite the abstract to show the main findings of this study.
3. The novelty of this article should be emphasized in the introduction, as should its advances beyond recently reported studies.
4. The cost of Au-Pd is also high compared with Ir-based catalysts
5. The morphogy and distribution of metal atoms over the support are critical factors for promoting the catalytic activity. Authros should provide any spectroscopic analysis like TEM analysis to show the morphogy of the alternative materials and the interfacial interaction between Au-Pd and TiO₂.
6. The XPS is a surface analysis, so other bulk analyses like ICP should be added.
7. The figures are inconsistent; for example, in Figure 2, some smaples were analyzed and some were not. Also, the binding energy values should be revised carefully.
8. The details related to the calculation of TOF should be added.
9. The LSV curves and IT on/off are missing.
10. A comparison table will be helpful.
11. The authors should cite some more recent references. TiO₂-base catalysts for oxygen evolution reactions, and it is recommended to cite these references

https://doi.org/10.1039/D1NA00274K & https://doi.org/10.1039/C9CY02366F

Author Response

Dear Reviewer, please see attached.

Kind regards.

Hicham

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have made great efforts to polish the manuscript, but two important references are missing (Dimension Engineering in Noble-Metal-Based Nanocatalysts, Catalysts 2024, 14, 9; Ce-Doped Ordered Mesoporous Cobalt Ferrite Phosphides as Robust Catalysts for Water Oxidation, Chem. Eur. J. 2020, 26, 13305-13310). After including them, I am willing to accept its publication.

Author Response

Thank you very much for finding our revised version to be suitable for publication.  We have added the two indicated references (now ref. 2 and 22) in the revised version.

Kind regards.

Hicham