【公開日：2024.07.25】【最終更新日：2024.06.26】

課題データ / Project Data

課題番号 / Project Issue Number

23AE0004

利用課題名 / Title

In-situ XAFS study of noble metal high entropy alloy nanoparticles with high stable and excellent activity under CO oxidation conditions

利用した実施機関 / Support Institute

日本原子力研究開発機構 / JAEA

機関外・機関内の利用 / External or Internal Use

外部利用/External Use

技術領域 / Technology Area

【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）-

【重要技術領域 / Important Technology Area】（主 / Main）革新的なエネルギー変換を可能とするマテリアル/Materials enabling innovative energy conversion（副 / Sub）-

キーワード / Keywords

XAFS, high-entropy alloy, CO oxidation, catalysts

利用者と利用形態 / User and Support Type

利用者名（課題申請者）/ User Name (Project Applicant)

Wu Dongshuang

所属名 / Affiliation

Nanyang Technological University

共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes

O. Seo,O. Sakata,J. Tang,Y. Wang,H. Gu

ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes

松村　大樹

利用形態 / Support Type

（主 / Main）共同研究/Joint Research（副 / Sub）-

利用した主な設備 / Equipment Used in This Project

AE-006：エネルギー分散型XAFS装置

報告書データ / Report

概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)

The purpose of this beam time is to observe the electronic structure change of metal alloy nanoparticles from monometallic to high-entropy alloy nanoparticles during the gas atmosphere.

実験 / Experimental

First, we observed the ex situ XAFS of the samples in the pellet form. For the in situ measurement, focusing on the In K-edge and Mn K-edge, the samples were pressurized and fitted into the in situ holder provided by Dr. Matsumura. The XAFS spectra were obtained under different atmospheres including vacuum, H₂ (1 bar and 9 bar), CO₂ (1 bar and 9 bar) with varying temperatures (RT to 773 K).

結果と考察 / Results and Discussion

During this beamtime, we have confirmed that all the liquid metal-based nanoparticles are covered by metal oxide layers on their surfaces. The thickness of the surface oxide layers is highly dependent on the particle size. Small NPs have thicker layers. We also found that the formed oxide layers have shorter M-O bond lengths than their corresponding crystalline metal oxides. These results are in line with the XPS as well as the XRD results. As for the liquid metal loaded on support, we found that the liquid metal tends to get lattice oxygen from the supported metal oxides and forms the amorphous liquid metal oxides. We also find that the coordination of metals is changed by changing the gas atmosphere. Moreover, MnO₂ was found to be unstable during the CO₂ and H₂ atmospheres. With a long-term gas phase treatment, MnCO₃ was found. This suggests the activity of MnO₂ for CO₂ hydrogenation but also the instability.

図・表・数式 / Figures, Tables and Equations

その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)

成果発表・成果利用 / Publication and Patents

論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)

口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.

特許 / Patents

特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件