Denary High-Entropy Oxide Nanoparticles Synthesized by a Continuous Supercritical Hydrothermal Flow Process

Shota Hanabata; Kohei Kusada; Tomokazu Yamamoto; Takaaki Toriyama; Syo Matsumura; Shogo Kawaguchi; Yoshiki Kubota; Yoshihide Nishida; Masaaki Haneda; Hiroshi Kitagawa

doi:10.1021/jacs.3c07351

Denary High-Entropy Oxide Nanoparticles Synthesized by a Continuous Supercritical Hydrothermal Flow Process

J Am Chem Soc. 2024 Jan 10;146(1):181-186. doi: 10.1021/jacs.3c07351. Epub 2023 Dec 28.

Authors

Shota Hanabata¹, Kohei Kusada^{1

2}, Tomokazu Yamamoto³, Takaaki Toriyama³, Syo Matsumura^{3

4}, Shogo Kawaguchi⁵, Yoshiki Kubota⁶, Yoshihide Nishida⁷, Masaaki Haneda⁷, Hiroshi Kitagawa¹

Affiliations

¹ Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
² The HAKUBI Center for Advanced Research, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
³ The Ultramicroscopy Research Center, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
⁴ Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
⁵ Center for Synchrotron Radiation Research, Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 675-5198, Japan.
⁶ Department of Physics, Graduate School of Science, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
⁷ Advanced Ceramics Research Center, Nagoya Institute of Technology, 10-6-29 Asahigaoka, Tajimi, Gifu 507-0071, Japan.

PMID: 38153046
DOI: 10.1021/jacs.3c07351

Abstract

High-entropy oxide nanoparticles (HEO NPs) have been intensively studied because of their attractive properties, such as high stability and enhanced catalytic activity. In this work, for the first time, denary HEO NPs were successfully synthesized using a continuous supercritical hydrothermal flow process without calcination. Interestingly, this process allows the formation of HEO NPs on the order of seconds at a relatively lower temperature. The synthesized HEO NPs contained 10 metal elements, La, Ca, Sr, Ba, Fe, Mn, Co, Ru, Pd, and Ir, and had a perovskite-type structure. Atomic-resolution high-angle annular dark-field scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy measurements revealed homogeneous dispersion of the 10 metal elements. The obtained HEO NPs also exhibited a higher catalytic activity for the CO oxidation reaction than that of the LaFeO₃ NPs.