| Project/Area Number |
22KJ2131
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| Project/Area Number (Other) |
22J10937 (2022)
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| Research Category |
Grant-in-Aid for JSPS Fellows
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| Allocation Type | Multi-year Fund (2023)
Single-year Grants (2022) |
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| Section | 国内 |
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| Review Section |
Basic Section 28030:Nanomaterials-related
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| Research Institution | Osaka University |
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Principal Investigator |
WANG YUELIN 大阪大学, 工学研究科, 特別研究員(DC2)
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| Project Period (FY) |
2023-03-08 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2023: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2022: ¥900,000 (Direct Cost: ¥900,000)
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| Keywords | DFT / AIMD / ORR / water/solid interfae / solvation energy / fuel cell |
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| Outline of Research at the Start |
We studied sp-N and pyridine N doped GDY to investigate the electrocatalytic activity of ORR. To simulate the real experiment condition, (1) Graphene (G) is applied as support under the N-doped GDY to enhance the electrode conductivity. (2) we use the ab inito molecular dynamics (AIMD) calculations to simulate the water environment with some H2O on surface to calculate the solvation energy of ORR intermediates. Finally, we performed the free energy diagram (based on thermodynamic analyses) to proving and predicting the experimentally observed activity trends for a range of materials.
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| Outline of Annual Research Achievements |
In this work, I use DFT calculations and AIMD simulations to investigate the ORR mechanism on sp-N1GDY/G and Pyri-NGDY/G. I got the following key points:
1. Under both vacuum and water conditions, ORR firstly proceeds on sp-N1GDY/G via the dissociative mechanism because O2 can be chemisorbed on a clean surface and easily dissociated rather than protonated to OOH*. However, OH* is strongly adsorbed on the sp-N1GDY/G surface, resulting in the weakening of the second O2 adsorption, and ORR takes place via the ET-OHP associative mechanism. Pyri-NGDY/G also prefers the ET-OHP associative mechanism.
2. From AIMD simulation, the H bond networks at the contact region of water and NGDY are mainly composed of six-membered rings H bond networks. H bond with water stabilizes each ORR intermediate and the free energy diagram with solvation effect agrees well with experimental data. Moreover, we found that using the ice-like bilayer model to construct the H bond networks can also give a reasonable estimation of ΔSol. Therefore, the ΔSol of these surfaces is independent of the water model, which arises from similar H bonds between adsorbates and water in the ice-like bilayer and AIMD H bond networks.
3. The sp-N1GDY/G with OH* pre-adsorbed surface has the highest ORR electrocatalytic activity and the neighboring C site of -COH-N moiety is the active site for ORR. Incorporation of solvation effect is of importance because η with solvation effect (0.46 V) is much closer to the experimental one (0.36 V).
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