A Comprehensive Review of the Development of Perovskite Oxide Anodes for Fossil Fuel-Based Solid Oxide Fuel Cells (SOFCs): Prospects and Challenges

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper provides a comprehensive review of the development of perovskite oxide anodes in fossil fuel based solid oxide fuel cells (SOFCs), and explores their prospects and challenges.

SOFCs play a key technological role in renewable energy as they can generate electricity cleanly and efficiently. This is a good research topic.

The below are comments:

1. This review paper contains a large scope. And this manuscript is very long. A large number of references are cited.
2. The article introduces the components and functions of SOFCs, particularly anode materials such as perovskite, Ruddlesden Popper oxide, and spinel, as well as their structure property relationships, including ionic and electronic conductivity, thermal expansion coefficient, and acidity/alkalinity.Those was good and classical for SOFCs. And the authors have presented those results in section 2.
3. The article also introduces some common reforming catalysts, including active sites, supports, and electrochemical testing, which have a significant impact on catalyst performance.
4. In addition, the article also explores the operating principles and thermodynamics of methane reforming. I believe the methane reformingcould be an individual topic. The section 3 can be moved to an separate article. This is on the methane reforming processes, but not SOFC.
5. The tittle can be revised with a focus on the methane reformingand SOFC application.
6. If the authors emphasize the data by 3D CFD simulation, this can be presented in an earlier section. First briefly discuss the fluid flow inside the SOFC.
7. In section 6.1 gas composition change section, the CFD results can be presented and summarized.
8. Section 7 is not lengthy as the other sections. Besides, the thermodynamic equilibrium can be a fundamental aspect and could be presented in a earlier section.
9. Besides, the computational fluid dynamics (CFD) model studies cannnot be grouped in the section numerical thermodynamic equilibrium simulations. This is somehow fluid flow and kinetics studies. A separate review on this topic are typically presented in papers.
10. You can replot a figure 7 to replace this one.

Author Response

This paper provides a comprehensive review of the development of perovskite oxide anodes in fossil fuel based solid oxide fuel cells (SOFCs), and explores their prospects and challenges.

SOFCs play a key technological role in renewable energy as they can generate electricity cleanly and efficiently. This is a good research topic.

Thank you for the opportunity to review the manuscript.

The below are comments:

 

1. This review paper contains a large scope. And this manuscript is very long. A large number of references are cited.

Since the manuscript try to have a comprehensive overview of SOFC applications by using perovskite catalysts the subsections include solid state chemistry, SOFCs components and functions. At the same time one of the important catalytic reactions for producing hydrogen and oxidate hydrogen for power generation is steam methane reforming reaction. As a result, manuscript covers steam methane reforming reaction mechanism and common applied catalysts. One of the novel sections of the manuscript is the simulation and modeling of electrochemical performance to predict catalytic activity in SOFCs applications. The research challenges in SOFCs by applying steam methane reforming shows an overview of catalyst stability and coke formation issues. In conclusion, I believe the sub-sections are well-designed to give readers the opportunity to having a broad understanding of SOFCs in different aspects.

1. The article introduces the components and functions of SOFCs, particularly anode materials such as perovskite, Ruddlesden Popper oxide, and spinel, as well as their structure property relationships, including ionic and electronic conductivity, thermal expansion coefficient, and acidity/alkalinity. Those was good and classical for SOFCs. And the authors have presented those results in section 2.

In Section 2 the manuscript reviews SOFCs parts including anode materials, substrate properties including ionic and electronic conductivity to elaborate on electrochemistry dependency on materials properties.

1. The article also introduces some common reforming catalysts, including active sites, supports, and electrochemical testing, which have a significant impact on catalyst performance.

In the reforming part as a common technique for high yield hydrogen production, POM, DRM, and BRM techniques are compared. After explaining why SMR is the most efficient technique the manuscript shows common methane reforming nickel-based catalysts and their operating conditions.

1. In addition, the article also explores the operating principles and thermodynamics of methane reforming. I believe the methane reforming could be an individual topic. The section 3 can be moved to a separate article. This is on the methane reforming processes, but not SOFC.

Thank you for the comment. The main reason for putting sections for methane reforming is one of the important aspects of SOFCs is using reforming reactions internally. Integration of SMR-SOFCs helping save more money since methane reforming reaction using the same heat source of SOFCs and produce power. As a result, I believe section 3 should be a part of the manuscript.

1. The tittle can be revised with a focus on the methane reforming and SOFC application.

Thank you for the smart comment. I believe the highlight part of fossil fuel-based applying in SOFCs indicates methane reforming reaction.

1. If the authors emphasize the data by 3D CFD simulation, this can be presented in an earlier section. First briefly discuss the fluid flow inside the SOFC.

Thank you for the comment. Regarding discussion about fluid flow on page 35 lines 1054 to 1071 were added.

1. In section 6.1 gas composition change section, the CFD results can be presented and summarized.

In Section 6 the manuscript talking about research challenges of SOFC in reforming and one of the influential factors in this area is gas composition change entering the active SOFC region. For the CFD (computational study) section 7 elaborating on CFD model of SMR reaction. I believe it is better these two parts be separated.

1. Section 7 is not lengthy as the other sections. Besides, the thermodynamic equilibrium can be a fundamental aspect and could be presented in a earlier section.

In Section 7, another related studies were added on page 34 lines 1005 to 1040. For thermodynamic since its combine to equilibrium simulations of SMR it is better to discuss in section 7.

1. Besides, the computational fluid dynamics (CFD) model studies cannot be grouped in the section numerical thermodynamic equilibrium simulations. This is somehow fluid flow and kinetics studies. A separate review on this topic are typically presented in papers.

Combining thermodynamic equilibrium with CFD simulations in SMR leads to considering chemical feasibility and realistic transport. To highlight the importance of thermodynamic equilibrium study in SMR I have added 3 more studies on section 7. This sections were added on page 34 lines 1005 to 1040.

 

1. You can replot a figure 7 to replace this one.

Fig 7 was replotted and replaced on page 7.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript is a comprehensive review of the development of perovskite oxide anodes for fossil fuel-based SOFC. The author systematizes current achievements, analyses key problems and suggests promising research directions. The work is important in view of the growing interest in sustainable energy technologies and contributes to the understanding of the material science aspects of SOFCs. The article is well structured and logically divided into sections: from an introduction to the principles of SOFC operation to analysis of catalyst deactivation mechanisms and modeling. This allows the general reader to progress through the subject in a consistent manner.

The manuscript may be published in the journal, but there are a number of issues that authors need to address. See my suggestions below.

(i) There are numerous typos and grammatical errors, some phrases are hard-to-read. This requires thorough proofreading of the text and alignment of terminology.

(ii) The topic chosen by the authors for the review is currently very topical, so there is a large number of papers. I recommend updating the list of literature used by adding publications from 2022-2024. Some relevant papers (e.g. on hybrid materials) are not mentioned.

(iii) As the title suggests, the authors have attempted not only to describe what is happening in this area of research, but also to discuss future perspectives. Most of the experiments are described under laboratory conditions. In this respect, it would be interesting to add a section on perspectives, discussing in particular industrial scaling, durability in real conditions, etc.

(iv) Are there examples of real usage of perovskite anodes? It will be useful to briefly discuss this aspect, including problems encountered in their use in commercial applications and ways to solve them.

Comments on the Quality of English Language

The English could be improved to more clearly express the research.

Author Response

The manuscript is a comprehensive review of the development of perovskite oxide anodes for fossil fuel-based SOFC. The author systematizes current achievements, analyses key problems and suggests promising research directions. The work is important in view of the growing interest in sustainable energy technologies and contributes to the understanding of the material science aspects of SOFCs. The article is well structured and logically divided into sections: from an introduction to the principles of SOFC operation to analysis of catalyst deactivation mechanisms and modeling. This allows the general reader to progress through the subject in a consistent manner.

The manuscript may be published in the journal, but there are a number of issues that authors need to address. See my suggestions below.

Thank you for your feedback and time to review the manuscript.

• There are numerous typos and grammatical errors, some phrases are hard-to-read. This requires thorough proofreading of the text and alignment of terminology.

The manuscript read carefully, and all typos and grammatical mistakes were corrected.

• The topic chosen by the authors for the review is currently very topical, so there is a large number of papers. I recommend updating the list of literature used by adding publications from 2022-2024. Some relevant papers (e.g. on hybrid materials) are not mentioned.

Some of the recent literatures were added to the manuscript on pages 3-4  lines between 83 to 94, page 9 lines between 232 to 240, page 21 lines 577 to 587, page 27 lines between 781 to 790.

• As the title suggests, the authors have attempted not only to describe what is happening in this area of research, but also to discuss future perspectives. Most of the experiments are described under laboratory conditions. In this respect, it would be interesting to add a section on perspectives, discussing in particular industrial scaling, durability in real conditions, etc.

In conclusion and future work section some of the future perspectives were discussed. It was added on page 36 lines between 1101 to 1103.

(iv) Are there examples of real usage of perovskite anodes? It will be useful to briefly discuss this aspect, including problems encountered in their use in commercial applications and ways to solve them.

Based on this comment following sections were added for applications of perovskite anodes in lab or large scale together with their challenges in SOFC system. Page 33 between lines 967 to 982 and Page 33 lines between 983 to 989.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have carefully revised the manuscript. It is now available for publication in the journal.