Zhao Yufeng, Lusk Mark T, Dillon Anne C, Heben Michael J, Zhang Shengbai B
National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
Nano Lett. 2008 Jan;8(1):157-61. doi: 10.1021/nl072321f. Epub 2007 Dec 11.
Transition-metal (TM) boride and carboride nanostructures are studied as model organometallic materials for hydrogen storage. The dispersed TM atoms function as H2 sorption centers on the surface of the boron or carbon-boron substrate. The flexibility offered in the variety of possible structures permits the study of the effect of the TM-TM distance on the storage capacity. When the TMs are too close to one another, TM-TM bonding reduces the capacity. Even when separated by distances larger than the normal TM-TM bond length, delocalization of TM valence electrons can still lower the hydrogen capacity. An optimal TM-TM distance for the structural motifs studied here is approximately 6 A. Our study also permitted the evaluation of new TM boride nanostructures. We predict a low-energy single-walled scandium triboride (ScB3) nanotube that can bind approximately 6.1 wt % hydrogen with a binding energy of 22 approximately 26 kJ/mol.
过渡金属（TM）硼化物和碳硼化物纳米结构作为储氢的模型有机金属材料被研究。分散的TM原子在硼或碳硼基底表面充当H₂吸附中心。各种可能结构所提供的灵活性使得能够研究TM-TM距离对储存容量的影响。当TM彼此过于靠近时，TM-TM键合会降低容量。即使被分隔的距离大于正常的TM-TM键长，TM价电子的离域仍会降低储氢容量。此处研究的结构基序的最佳TM-TM距离约为6埃。我们的研究还允许对新型TM硼化物纳米结构进行评估。我们预测一种低能量的单壁三硼化钪（ScB₃）纳米管，它可以结合约6.1 wt%的氢，结合能为22至26 kJ/mol。
