【公開日：2023.08.01】【最終更新日：2023.07.28】

課題データ / Project Data

課題番号 / Project Issue Number

22OS0032

利用課題名 / Title

高分解能電子顕微鏡観察による炭化金属ナノ結晶の構造解析

利用した実施機関 / Support Institute

大阪大学 / Osaka Univ.

機関外・機関内の利用 / External or Internal Use

内部利用（ARIM事業参画者）/Internal Use (by ARIM members)

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）マルチマテリアル化技術・次世代高分子マテリアル/Multi-material technologies / Next-generation high-molecular materials（副 / Sub）次世代ナノスケールマテリアル/Next-generation nanoscale materials

キーワード / Keywords

ナノ粒子, 触媒, 有機合成, グリーンケミストリ―,電子顕微鏡/Electron microscopy,電子回折/Electron diffraction

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)

水垣 共雄

所属名 / Affiliation

大阪大学

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

山口渉

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

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

OS-008：電界放出型200kV高分解能電子顕微鏡

報告書データ / Report

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

Introduction of additional elements into metal nanoparticles is a key technique for developing novel catalysts. Among them, non-noble metal carbides have attracted significant attentions as electro- and photocatalysts. Compared to non-noble metal carbides, the catalytic potential of noble metal carbides, such as palladium carbides (PdC_x), has rarely been studied due to their limited synthetic methods. Therefore, in this work, we synthesized well-defined PdC_x with cubic morphology by the hydrothermal method and explored their catalytic functions for the hydrogenation of nitrobenzene to aniline. Notably, PdC_x showed significantly higher turnover frequency (TOF) than Pd nanocubes (Pd cubes), demonstrating that the introduction of carbon atoms imparted superior activity to Pd cubes.

実験 / Experimental

Pd cubes were prepared by the surfactant-mediated method using capping agents. Subsequently, the obtained Pd cubes were treated by the hydrothermal method to produce PdC_x. Transmission electron microscopy (TEM) images were obtained using a Hitachi HF-2000 microscope operated at 200 kV.

結果と考察 / Results and Discussion

TEM images of Pd cubes show the formation of cubic particles ranging from 7–20 nm in width (Figures 1a-c). After the carbon-doping of Pd cubes, their particle size and cubic shape were retained (Figures 1d-f). To investigate the catalytic potential of PdC_x, the hydrogenation of nitrobenzene to aniline using PdC_x and Pd cubes was carried out at 30 ^oC under 1 bar of H₂ (Figure 2). Pd cubes exhibited poor activity to afford a trace amount of aniline, while PdC_x showed over 500 times higher activity based on the TOF than Pd cubes. PdC_x also represented high TOF values independent of their crystalline sizes. These results clearly demonstrate that the incorporating carbon atoms play a key role in improving catalytic activity of Pd cubes. In conclusion, selective and size-controllable synthesis of PdC_x was achieved. PdC_x gave significantly higher TOF for the hydrogenation of nitrobenzene than Pd cubes, demonstrating the high catalytic potential of PdC_x in organic synthesis. Incorporation of carbon atoms strongly improves the catalysis of single Pd nanoparticles, which will open up an exciting research field on noble metal carbide catalysts for organic synthesis.

図・表・数式 / Figures, Tables and Equations

Figure 1. TEM images of Pd and PdC_x nanocubes with controllable particle size.

Figure 2. Performance of nano PdC_x and nano Pd for the reduction of nitrobenzene.

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

This work was supported by JSPS KAKENHI Grant No. 21K04776.

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.

1. Sarmiento Diaz Marcelo Junior, Sho Yamaguchi, Takato Mitsudome, Tomoo Mizugaki, Osaka-Kansai International Symposium on Catalysis (OKCAT2022) (2022.11.11).

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