IrOx Supported on Submicron-Sized Anatase TiO2 as a Catalyst for the Oxygen Evolution Reaction
, Carlos Calabrés-Casellas 1, Maria Sarret 1, Teresa Andreu 1,* and Pere L. Cabot 2,*
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe presented article is devoted to the synthesis of highly efficient iridium-containing catalysts on an oxide carrier for OER to produce green hydrogen. It is known that the use of various oxide carriers can significantly improve the characteristics of Ir catalysts, increase their stability and, as a result, reduce the content of precious metal in devices. On the other hand, due to the insufficiently high electrical conductivity of oxide materials, it is necessary to select the optimal ratio of iridium and the carrier. In general, the presented work is of undoubted interest for the development of efficient catalysts. However, several comments should be noted.
- The structure of the obtained materials has not been studied by X-ray diffraction. This method is standard and allows you to determine the phase composition of the material and calculate the average crystallite size using the Scherrer formula.
- XPS data are presented for Ir/TNT (40:60) in comparison with Ir Black, why are they not shown for Ir/TiO2 materials, for example, for the most active Ir/TiO2 (10:90).
- More information is needed about the Ir Black comparison sample, why was no comparison made with a commercial Ir/TiO2 material?
- Why was this catalyst loading on the electrode chosen? Perhaps the characteristics of the materials depend on the thickness of the catalytic layer, which can distort the data for Ir Black with a loading of 80 µg cm-2. Will this dependence be preserved when the loading is changed?
Why was only one iridium loading (40:60) studied for nanotubes? Perhaps with a more optimal amount of iridium, the specific characteristics of the material were significantly higher. In general, the material on nanotubes looks somewhat alien and it can be stated that the structure of nanotubes does not give a positive effect compared to standard TiO2.
It would be useful to add CV for TiO2 and nanotubes and determine their area. In Figure 4, the appearance of the Ir/TiO2(05:95) curve is significantly different from the others; it is necessary to explain the appearance of this curve.
The ESA calculation needs to be presented in more detail and summarized into one formula.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe article is well written in line with scientific soundness.
However, several concerns should
be addressed before acceptance.
1. To prove the crystalline behavior XRD may be
Ggiven for each catalyst.
2. Although the authors explained the catalysis
with onset potential for OER but another important
indicator that is Tafel slope analyses are missing.
3. Turn over frequency is very important to show
the catalysis.
4. Please specify Faradaic efficiency for each catalyst.
5. IrOx on TiO2 shows reversible 1e ET process.
Please compare reversibility characters in terms
of potential range for each catalyst. Does this process
have any involvement in catalysis of OER
6. A related article based on Ti/IrOx pertaining to HER published in Electrochimica Acta by Fahmidul Islam should be cited.
Author Response
Olease see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors answered the questions and made the necessary changes to the text of the article. The article may be accepted for publication in the journal.
