Specific Synchrotron Radiation Facilities Users Community (SpRUC)

The solid?liquid interface plays a crucial role as the reaction field for an extremely wide range of practical phenomena, including energy and environmental materials such as batteries, electrolytes, corrosion protection, and heterogeneous catalysis, as well as wetting, friction and lubrication, and the functional expression of polymer materials. However, at the interface, chemical reactions, charge transfer, mass transport, and structural relaxation proceed simultaneously and strongly influence one another, and the temporal and spatial scales involved are diverse, leaving numerous unresolved issues, including those related to non-equilibrium statistical mechanics. To understand the essence of these phenomena, advanced in situ/operando measurements that simultaneously capture the entire interface under real-world conditions, and the integrated analysis based on them, are indispensable. This research group aims to understand interface functionality by transcending the conventional framework that separates the solid?liquid interface into a “solid surface” and a “liquid side.” Instead, it views the interface as a single dynamic system in which the structures and electronic states of both the solid and liquid sides are interconnected in response to external fields such as potential, current, light, temperature, stress, and flow. Specifically, we adopt a perspective that views the liquid side (solvent, ions, reaction species) not merely as an environment, but as an integral “part of the material” inseparable from the solid, aiming to understand the concerted functional expression at the interface. Therefore, this research group prioritizes the advancement of measurement and analysis techniques that simultaneously capture information from the liquid side?such as solvent/ion rearrangement and the formation of reaction intermediates?alongside changes in the solid surface structure and electronic state under identical conditions and at the same time. This enables the elucidation of phenomena such as electric double layer formation, adsorption/desorption processes, stabilization mechanisms of reaction intermediates, and dynamic modulation of wettability and friction properties as causal relationships across the entire interface. From the perspective of synchrotron radiation science, facilities such as SPring-8 and NanoTerasu, along with XFEL facilities, serve as the core measurement infrastructure for capturing the “interconnection between the solid and liquid sides” in situ/operando under applied external fields targeted by this research group. X-rays can access the interface region through sample cells, enabling simultaneous tracking of solid surface changes and solvent/ion rearrangement by leveraging elemental and chemical state selectivity. Furthermore, multifaceted observation integrating diffraction, scattering, and spectroscopy experimentally visualizes the causal relationships underlying interface functionality, connecting to theoretical development and material design. This research group aims to advance solid?liquid interface studies incorporating real-world environments and operating conditions, based on cutting-edge synchrotron radiation measurement techniques, thereby contributing to the fundamental understanding of unexplained phenomena and the creation of new material and device design guidelines.