Kim Changwook, Choi Yong Soo, Lee Seung Mi, Park Joon T, Kim Bongsoo, Lee Young Hee
Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea.
J Am Chem Soc. 2002 Aug 21;124(33):9906-11. doi: 10.1021/ja026538h.
We have investigated systematically the effects of various gas adsorbates (H2, N2, O2, and H2O) on the electronic structures and the field emission properties of open edges of single-walled carbon nanotubes by density functional calculations. All of the molecules, except N2, dissociate and chemisorb on open nanotube edges with large adsorption energies. The Fermi levels are moved toward the valence (conduction) bands for O2 (H2, H2O) adsorption induced by the Mulliken charge transfer on the tube edge. The Fermi level shift for N2 adsorption is negligible. Adsorption of H2O enhances the field emission current, whereas H2 adsorption does not affect the field emission current much because of the absence of the density of states near the Fermi level. The correlation of the electronic structures and the field emission current is further discussed.
我们通过密度泛函计算系统地研究了各种气体吸附质（H₂、N₂、O₂和H₂O）对单壁碳纳米管开放边缘的电子结构和场发射特性的影响。除N₂外，所有分子都会解离并以较大的吸附能化学吸附在开放的纳米管边缘。由于管边缘的穆利肯电荷转移，O₂（H₂、H₂O）吸附会使费米能级向价带（导带）移动。N₂吸附引起的费米能级移动可忽略不计。H₂O的吸附增强了场发射电流，而H₂的吸附对场发射电流影响不大，因为费米能级附近不存在态密度。进一步讨论了电子结构与场发射电流之间的相关性。
