Affiliation:
1. MDX Research Center for Element Strategy International Research Frontiers Initiative Tokyo Institute of Technology 4259 Nagatsuta, Midori‐ku Yokohama 226–8503 Japan
2. Research Center for Materials Nanoarchitectonics National Institute for Materials Science 1‐1 Namiki Tsukuba Ibaraki 305‐0044 Japan
3. Advanced Institute for Materials Research (WPI‐AIMR) Tohoku University Sendai 980–8577 Japan
Abstract
AbstractOxyhydrides have attracted attention as materials with various unique properties derived from lattice hydride ions (H−). However, their instability makes synthesis by conventional thermal synthesis methods difficult, so an appropriate synthesis strategy is required. Here, the mechanochemical synthesis of perovskite oxyhydrides BaREO2H (RE = Y, Sc) for catalyst applications is reported. The formation of BaYO2H is known to be thermodynamically unstable; however, a mechanochemical process that inevitably proceeds under non‐equilibrium conditions enables the synthesis of such a metastable oxyhydride material without any heat treatment. Furthermore, BaScO2H, which is typically obtained at very high temperatures (1000 °C) and pressure (>4 GPa), is successfully synthesized at room temperature by the mechanochemical method. The ammonia synthesis reaction over these oxyhydrides supporting Ru is significantly enhanced at low temperatures, and the ammonia synthesis rates are significantly higher than conventional oxide‐supported Ru catalysts. The mechanochemically synthesized BaREO2H has many anionic electrons with low work function at the site of H− vacancies, which enables strong electron donation to Ru and the storage of excess hydrogen adatoms from the Ru surface that results in high catalytic performance.