Phase Control of Solid-Solution Nanoparticles beyond the Phase Diagram for Enhanced Catalytic Properties

Dongshuang Wu; Kohei Kusada; Susan Meñez Aspera; Hiroshi Nakanishi; Yanna Chen; Okkyun Seo; Chulho Song; Jaemyung Kim; Satoshi Hiroi; Osami Sakata; Tomokazu Yamamoto; Syo Matsumura; Yusuke Nanba; Michihisa Koyama; Naoki Ogiwara; Shogo Kawaguchi; Yoshiki Kubota; Hiroshi Kitagawa

doi:10.1021/acsmaterialsau.1c00048

Phase Control of Solid-Solution Nanoparticles beyond the Phase Diagram for Enhanced Catalytic Properties

ACS Mater Au. 2021 Nov 15;2(2):110-116. doi: 10.1021/acsmaterialsau.1c00048. eCollection 2022 Mar 9.

Authors

Dongshuang Wu¹, Kohei Kusada¹, Susan Meñez Aspera², Hiroshi Nakanishi², Yanna Chen³, Okkyun Seo³, Chulho Song³, Jaemyung Kim³, Satoshi Hiroi³, Osami Sakata³, Tomokazu Yamamoto^{4

5}, Syo Matsumura^{4

5}, Yusuke Nanba^{6

7}, Michihisa Koyama^{6

7}, Naoki Ogiwara¹, Shogo Kawaguchi⁸, Yoshiki Kubota⁹, Hiroshi Kitagawa¹

Affiliations

¹ Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
² National Institute of Technology, Akashi College 679-3 Nishioka, Uozumi, Akashi, Hyogo 674-8501, Japan.
³ Synchrotron X-ray Group and Synchrotron X-ray Station at SPring-8, National Institute for Materials Science, Sayo, Hyogo 679-5148, Japan.
⁴ Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395, Japan.
⁵ The Ultramicroscopy Research Center, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395, Japan.
⁶ Center for Green Research on Energy and Environmental Materials, National Institute for Materials Science. 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
⁷ Research Initiative for Supra-Materials, Shinshu University, 4-17-1 Wakasato, Nagano, Nagano 380-8553, Japan.
⁸ Research & Utilization Division, Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan.
⁹ Department of Physical Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan.

Abstract

The crystal structure, which intrinsically affects the properties of solids, is determined by the constituent elements and composition of solids. Therefore, it cannot be easily controlled beyond the phase diagram because of thermodynamic limitations. Here, we demonstrate the first example of controlling the crystal structures of a solid-solution nanoparticle (NP) entirely without changing its composition and size. We synthesized face-centered cubic (fcc) or hexagonal close-packed (hcp) structured Pd _x Ru_1-x NPs (x = 0.4, 0.5, and 0.6), although they cannot be synthesized as bulk materials. Crystal-structure control greatly improves the catalytic properties; that is, the hcp-Pd _x Ru_1-x NPs exceed their fcc counterparts toward the oxygen evolution reaction (OER) in corrosive acid. These NPs only require an overpotential (η) of 200 mV at 10 mA cm^-2, can maintain the activity for more than 20 h, greatly outperforming the fcc-Pd_0.4Ru_0.6 NPs (η = 280 mV, 9 min), and are among the most efficient OER catalysts reported. Synchrotron X-ray-based spectroscopy, atomic-resolution electron microscopy, and density functional theory (DFT) calculations suggest that the enhanced OER performance of hcp-PdRu originates from the high stability against oxidative dissolution.