ElectroActive Materials Team

Achieving hole conduction in wide-gap compound semiconductors is challenging because the anionic p orbitals that form the valence band maximum (VBM), which acts as the conduction pathway for holes, are highly localized. We proposed a new method to modify the VBM through covalent interactions with filled cationic p orbitals. In rocksalt-type LaN, the interaction between N 2p orbitals and filled La 5p orbitals broadens the valence band width and imparts the delocalization of the holes (Fig. 1(a))[ 1 ].

Barium orthosilicate oxynitride-hydride Ba₃SiO_5-xN_yH_z is a newly synthesized compound as a transition-metal-free catalyst for efficient ammonia synthesis. Using DFT calculations, we determined the optimized structure for Ba₃SiO_2.5NH₂ consists of SiO₂NH tetrahedra and Ba₆H octahedra (Fig.1(b)), which is prone to anion vacancies and activates hydrogen and nitrogen. [ 2 ]. A striking result is that this material exhibits high catalytic activity for NH₃ synthesis, comparable to that of Ru-Cs-loaded MgO, a milestone catalyst, without loading a transition metal.