Matsuzaki Kohei, Saito Kei, Ikeda Yoichi, Nambu Yusuke, Yashima Masatomo
Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1-W4-17, O-okayama, Meguro-ku, Tokyo 152-8551, Japan.
Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
J Am Chem Soc. 2024 Jul 10;146(27):18544-18555. doi: 10.1021/jacs.4c04325. Epub 2024 Jun 25.
Proton conductors have potential applications such as fuel cells, electrolysis cells, and sensors. These applications require new materials with high proton conductivity and high chemical stability at intermediate temperatures. Herein we report a series of new hexagonal perovskite-related oxides, BaAlSnO ( = Gd, Dy, Ho, Y, Er, Tm, and Yb). BaErAlSnO exhibited a high proton conductivity without chemical doping (e.g., 0.01 S cm at 303 °C), which is attributed to its high proton concentration and diffusion coefficient. The high diffusion coefficient of BaErAlSnO can be attributed to the fast proton migration in the octahedral layers. The high proton concentration is attributed to full hydration in hydrated BaErAlSnO and the large amount of intrinsic oxygen vacancies in the dry sample, as evidenced by both neutron diffraction and thermogravimetric analysis. BaErAlSnO was found to exhibit high chemical stability under wet atmospheres of O, air, H, and CO. High proton conductivity and high chemical stability indicate that BaErAlSnO is a superior proton conductor. BaAlSnO ( = Gd, Dy, Ho, Y, Tm, and Yb) exhibited high electrical conductivity in wet N, suggesting that these materials also exhibit high proton conductivity. These findings will open new avenues for proton conductors. The high proton conductivity via full hydration and fast proton migration in octahedral layers in highly oxygen-deficient hexagonal perovskite-related materials would be an effective strategy for developing next-generation proton conductors.
质子导体在燃料电池、电解池和传感器等方面具有潜在应用。这些应用需要在中温下具有高质子传导率和高化学稳定性的新材料。在此，我们报道了一系列新型的六方钙钛矿相关氧化物，BaAlSnO（= Gd、Dy、Ho、Y、Er、Tm和Yb）。BaErAlSnO在未进行化学掺杂的情况下表现出高质子传导率（例如，在303°C时为0.01 S cm），这归因于其高质子浓度和扩散系数。BaErAlSnO的高扩散系数可归因于质子在八面体层中的快速迁移。高质子浓度归因于水合BaErAlSnO中的完全水合作用以及干燥样品中大量的本征氧空位，中子衍射和热重分析均证明了这一点。发现BaErAlSnO在O、空气、H和CO的潮湿气氛下表现出高化学稳定性。高质子传导率和高化学稳定性表明BaErAlSnO是一种优异的质子导体。BaAlSnO（= Gd、Dy、Ho、Y、Tm和Yb）在潮湿的N中表现出高电导率, 这表明这些材料也表现出高质子传导率。这些发现将为质子导体开辟新的途径。通过高度缺氧的六方钙钛矿相关材料中的完全水合作用和质子在八面体层中的快速迁移来实现高质子传导率，将是开发下一代质子导体的有效策略。
