Mechanocatalytic Hydrogen Generation in Centrosymmetric Barium Dititanate.

Novel phase of nano materials that break the traditional structural constraints are highly desirable, particularly in the field of mechanocatalysis, offering versatile applications ranging from energy to medical diagnosis and treatment. In this work, a distinct layered barium dititanate (BaTi 2 O 5 ) nanocrystals using a pH-modulated hydrothermal method is successfully synthesized. These nanocrystals exhibit outstanding hydrogen generation capability (1160 µmol g -1  h -1 in pure water) and demonstrate remarkable performance in organic dye degradation using ultrasonication. The crystal structure of this newly discovered BaTi 2 O 5 phase, is determined by a combination of synchrotron Powder Diffraction refinement and X-ray adsorption techniques, including X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS). Density Functional Theory calculations revealed that the newly-discovered BaTi 2 O 5 phase demonstrates dipole moments along the z-axis, distributed in an antiparallel direction within a single unit cell. These inherent dipoles induce a surface polarization and a ferroelectric-flexoelectric response under mechanical stimuli when the materials go to nano dimension. With a band alignment well-suitable for hydrogen and reactive oxygen species generation, this BaTi 2 O 5 phase demonstrates promising potential for Mechanocatalysis. The discovery of this distinct phase not only enriches the material candidates for mechanocatalysis but also provides valuable insights.