Solid-State Protonics Based on Metal-Oxide Clusters

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K18975
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 34:Inorganic/coordination chemistry, analytical chemistry, and related fields
• Research Institution: The University of Tokyo
• Principal Investigator: Uchida Sayaka 東京大学, 大学院総合文化研究科, 准教授 (10361510)
• Co-Investigator(Kenkyū-buntansha): 菊川 雄司 金沢大学, 物質化学系, 准教授 (10637474)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: プロトン伝導 / 結晶多形 / 金属酸化物クラスター / ビスマス錯体

Outline of Final Research Achievements

In recent years, crystal polymorphs with the same composition but different crystal structures have attracted much attention in the field of crystal engineering. In this study, we synthesized ionic crystals composed of a mononuclear bismuth complex and polyoxometalate (POM). The proton conductivity of the crystals have shown that crystals with a large pore volume, which can accomodate more water molecules into the pore when humidified, show higher proton conductivity. Ionic crystals containing DMF ligands, in which tertiary amines are thought to function as proton acceptors, were also found to exhibit high proton conductivity.

Free Research Field

無機化学

Academic Significance and Societal Importance of the Research Achievements

化石燃料への依存度の少ない低炭素社会の実現に向け、水素をエネルギー源として使いこなす科学技術の重要性が高まっている。固体中のプロトンのふるまい（固体プロトニクス）に関する研究は「プロトン解離の容易さ・水素（プロトン）の電子密度の低下・プロトンキャリア密度の増加」すなわち、液体酸における「酸解離定数の増加」に代表される酸機能向上に重点がおかれてきた。一方、本研究により、結晶多形の利用により固体中のプロトン伝導性を変調できることが明らかとなった。