Department of Materials Science and Engineering, Tokyo Institute of Technology, Tokyo, 152-8552, Japan.
Department of Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8571, Japan.
Nat Commun. 2019 Oct 25;10(1):4880. doi: 10.1038/s41467-019-12903-1.
Hydrogen boride nanosheets (HB sheets) are facilely synthesized via ion-exchange treatment on magnesium diboride (MgB) in an acetonitrile solution. Optical absorption and fluorescence spectra of HB sheets indicate that their bandgap energy is 2.8 eV. According to first-principles calculations, optical absorption seen at 2.8 eV is assigned to the electron transition between the σ-bonding states of B and H orbitals. In addition, density functional theory (DFT) calculations suggest the other allowed transition from the σ-bonding state of B and H orbitals to the antibonding state with the gap of 3.8 eV. Significant gaseous H release is found to occur only under photoirradiation, which causes the electron transition from the σ-bonding state to the antibonding state even under mild ambient conditions. The amount of H released from the irradiated HB sheets is estimated to be 8 wt%, indicating that the sheets have a high H-storage capacity compared with previously reported metal H-storage materials.
硼化氢纳米片（HB 纳米片）可通过在乙腈溶液中对二硼化镁（MgB）进行离子交换处理来轻松合成。HB 纳米片的光吸收和荧光光谱表明其带隙能为 2.8eV。根据第一性原理计算，在 2.8eV 处观察到的光吸收归因于 B 和 H 轨道的σ键态之间的电子跃迁。此外，密度泛函理论（DFT）计算表明，另一个允许的从 B 和 H 轨道的σ键态到带隙为 3.8eV 的反键态的跃迁。仅在光照下才发现显著的气态 H 释放，这导致即使在温和的环境条件下，电子也从σ键态跃迁到反键态。从辐照的 HB 纳米片中释放的 H 的量估计为 8wt%，表明与先前报道的金属 H 存储材料相比，该纳米片具有高的 H 存储容量。
