Hydrogen Ion Materials Group

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Hydrogen ions, such as protons and hydrides, play a central role in materials functions as reaction active sites and charge carriers in catalysts and electrochemical devices. We focus on the unique chemical states, diffusion behavior, and reactivity of hydrogen ions in solids, and are engaged in the development of innovative hydrogen-ion-based materials—particularly catalysts—and in elucidating their underlying mechanisms.
Our research begins with designs guided by an original intuition for materials combined with computational science, and is advanced through a unique approach that integrates in-house synthesis setups for material exploration with state-of-the-art ion beam instruments highly sensitive to hydrogen and surfaces.

In addition to first-principles calculation software and machine-learning-based molecular dynamics simulators for the design of hydrogen-ion materials, we are equipped with a wide range of experimental facilities for synthesis, characterization, and analysis, including various electric furnaces, electrochemical measurement systems, spectroscopic instruments, and catalytic performance evaluation systems. Furthermore, our laboratory possesses state-of-the-art ion beam instruments capable of probing hydrogen at surfaces and interfaces, such as a dynamic secondary ion mass spectrometer (SIMS), an in-house–built static SIMS system, low-energy ion scattering, and low-energy elastic recoil detection analysis.

Photograph of the comprehensive low-energy ion beam analysis system.

This system enables the evaluation of crystallinity and electronic states at the outermost surface of a sample, as well as compositional and structural analysis of hydrogen-containing light elements and metals.

• The world’s highest hydride-ion conductivity at room temperature
• Semiconductor sensor capable of selectively detecting hydrogen
• Identification of hydrogen as the cause of humidity-induced degradation in multilayer ceramic capacitors

(a) Arrhenius plots of ionic conductivity for lanthanum oxyhydride (symbols) and representative proton conductors (solid lines).
(b) Hydride dynamics observed in molecular dynamics simulations using machine-learning potentials.

• Magnetic Refrigeration System Group
• Superconducting System Group
• Hydrogen Production Catalyst Materials Group
• Advanced Superconducting Wire Group
• Hydrogen Ion Materials Group
• Electrochemical Energy Conversion Team