Biomass Photoreforming for Hydrogen Production over Hierarchical 3DOM TiO₂-Au-CdS

Round 1

Reviewer 1 Report

The authors reported the biomass photoreforming for hydrogen production over hierarchically 3DOM TiO2-Au-CdS. This work is interesting and meaningful. This manuscript could be considered for publishing in Catalysts after addressing the following issues.

1. Please observe the lattice fringes of Au and TiO2 by HR-TEM as shown in Fig. 2c.
2. It seems that the fitting of Au 4f level in Fig.3b did not fulfil the fitting rules of XPS peaks (ratio of peak area: 2p3/2:2p1/2=2:1; 2d5/2:2d3/2=3:2; 2f7/2:2f5/2=4:3. Refer to: Journal of Colloid and Interface Science 608 (2022) 2058–2065; Chemical Engineering Journal 401 (2020) 126135). Moreover, please provide the XPS results of individual TiO2, Au, and CdS for comparing with 3DOM TiO2-Au-CdS.
3. Please provide the UV-vis results of individual TiO2, Au, and CdS for comparing with 3DOM TiO2-Au-CdS as shown in Fig. 4.
4. Please investigate the activities of photocatalytic H2 generation under visible light irradiation. Moreover, please evaluate the apparent quantum yields (refer to: Chemical Engineering Journal 431 (2022) 134101) if possible.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The authors reported the photocatalytic H2 production from the aqueous solution containing glucose, cellobiose or dissolving pulp over the ternary TiO2-Au-CdS 3D ordered macroporous structure. This work is very interesting, and I recommend it publish in Catalysts afeter minor revision.

1. In the Experimental, the authors seemed to conduct their H2 production experiment without the removal of air. Can you explain the reaction pathway of H2 production from Glucose?
2. The authors mentioned that CO is a main product. Then how did it come from? And what about CO2?
3. The authors mentioned “The hydrogen production is triggered by the proton reduction reaction by photogenerated electrons. Herein, it could be foreseen that acid condition with more concentration of protons should be more beneficial for hydrogen production.”Surely the proton reduction from H+ is not the key mechanism for H2 production. More detailed mechanism should be provided.
4. More references should be cited. Adv. Colloid Interface Sci., 2021, 295, 102493 and J. Phys. Chem. Lett. 2013, 4 (20), 3479-3483.
5. The writing should be improved before publication.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Zhong et al. present a very interesting topic, which is photocatalytic hydrogen production via the photoreforming of biomass over modified TiO₂ photocatalysts. The manuscript is well written and the results are well presented. However, there are some issues that need to be addressed:

1- In the introduction, the authors should write more about the previous works in the field of photocatalytic reforming over TiO₂ photocatalysts. The authors can cite the followings: (10.1016/j.jphotochem.2018.04.008), (10.3390/ma13173800), and (10.1002/cssc.201200085)

2- In the introduction, the authors should present more facts about TiO2 photocatalysis including its advantages and disadvantages.

3- In some publications, Pt as a catalyst shows better performance than Au when using a Xe lamp as a light source (e.g. 10.1021/acsaem.0c00826). Have the authors tried to use Pt or dual Pt-Au catalysts instead of Au? If yes, please mention the results. If not, the authors should mention this point.

4- The authors should mention the mechanisms of the photoreforming of glucose, including the reaction of CH₄ and CO formation.

5- It has been shown, that the formation of CH₄ would consume H radicals. From the results, it can be seen that although H₂ has a high formation rate from Glucose, higher CH₄ amounts have been formed as well. Can the authors comment on this!

6- The authors mentioned that the highest H₂ production was achieved at pH = 1. At pH < pHzpc of TiO₂ (between 5 - 6), the surface charge is mostly positive. At acidic pH, OH groups on glucose could be reversibly protonated. From this point of view, the interaction between TiO₂ surface and glucose is minimum in an acidic medium, thus the reaction could be negatively affected. Can the authors explain their results?

7- It is highly recommended to study the adsorption of each of the three substrates on the photocatalyst surface and see any relation to the photocatalytic activity. 

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Accept.

Author Response

Thanks again for reviewer's positive and constructive suggestions!

Reviewer 3 Report

Zhong et al. present a very interesting topic, which is photocatalytic hydrogen production via the photoreforming of biomass. The manuscript in its revised version is well written and the results are well presented. The authors have responded to the most critical points, therefore the manuscript can be accepted in its revised version.

Author Response

Thanks again for reviewer's positive and constructive suggestions!