First-Principles Calculation and Multi-Scale Observation for a Carbon Deposition on a SOFC Anode Near the Interface
| Autor: | Katsunori Hanamura, Teppei Ogura, Hirotatsu Watanabe |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | ECS Transactions. 103:825-830 |
| ISSN: | 1938-6737 1938-5862 |
| DOI: | 10.1149/10301.0825ecst |
| Popis: | The nickel/yttria-stabilized zirconia (Ni/YSZ) and nickel/scandia-stabilized zirconia (Ni/ScSZ) have widely used as an anode for solid oxide fuel cells (SOFCs). The high operation temperature allows an SOFC to operate on a wide range of fuels, including hydrocarbons and coal syngas. Ni is also a catalyst for carbon deposition reactions which destroy the anode microstructure. Meanwhile, the carbon deposited on the electrode can be used for different ways. It is important to control the carbon deposition on the electrode; therefore, the carbon deposition model needs to be developed. In this study, carbon deposition site in the Ni/YSZ and Ni/ScSZ was studied through first-principles calculation and multi-scale observation using SEM and TEM. Observation showed that the carbon deposition was progressed not in the overall Ni surface but in the specific sites such as the interfaces and Ni(211) facet at low temperature. The carbon deposition rate strongly depended on the electrode structure at microscales. All calculations here are performed employing the periodic density functional theory (DFT) method implemented in the Vienna Ab-Initio Simulation Package (VASP). The Ni/YSZ and Ni/ScSZ atomic models are developed to discuss the CH adsorption which is the initial step of the carbon deposition. The CH adsorption energy in the concentrated vacancies at the Ni/YSZ interface was much lower than that in the Ni(111) facet, indicating that concentrated vacancies become the active site of the carbon deposition. However, the CH adsorption energy in the dispersed vacancies are almost the same as that in the Ni(111) facet. It is shown that vacancy patterns play an important role in the carbon deposition rate. The impact of dopant in the anode on the carbon deposition is also studied. DFT calculation gives an useful hint to develop the carbon deposition model with considering the electrode structure. |
| Databáze: | OpenAIRE |
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