12CaO·7Al₂O₃ 表面 H⁻ 阴离子发射的特征与机理

Features and mechanism of H- anion emission from 12 CaO x 7 Al2O3 surface.

作者信息

Huang Fan, Li Jiang, Wang Lian, Dong Ting, Tu Jing, Torimoto Yoshifumi, Sadakata Masayoshi, Li Quanxin

机构信息

Department of Chemical Physics, Lab of Biomass Clean Energy, University of Science & Technology of China, Hefei, Anhui, 230026, PR China.

出版信息

J Phys Chem B. 2005 Jun 23;109(24):12032-7. doi: 10.1021/jp050006g.

DOI:10.1021/jp050006g

PMID:16852484

Abstract

The hydrogen anion (H-) and other anionic species (O-, OH-, e-) in the gas phase, emitted from the synthesized crystal surface of 12 CaO x 7 Al2O3-H- (C12A7-H-), have been observed. The emission intensity of all the anionic species strongly depends on the sample surface temperature and the extraction field. H- has the highest emission branch ratio, and the extraction field can reduce its apparent activation energy. H- emission current at a microA/cm2-level has been achieved, which is about 4 orders of magnitude higher than that obtained from the thermal desorption process of CaH2. The observed anions of H- and OH- are attributed to their migration from the C12A7-H- cages onto the surface [i.e., Y-(cages) --> Y-(surface) --> Y-(gas phase) (Y = H, OH)]. The weak O- and electron emission would both arise from the dissociation of O2-: O2-(surface) --> O-(surface) + e-(surface) --> O-(gas phase) + e-(space).

摘要

已观察到从12CaO·7Al₂O₃ - H⁻（C12A7 - H⁻）合成晶体表面发射出的气相中的氢阴离子（H⁻）和其他阴离子物种（O⁻、OH⁻、e⁻）。所有阴离子物种的发射强度强烈依赖于样品表面温度和提取场。H⁻具有最高的发射分支比，并且提取场可以降低其表观活化能。已实现了微安/平方厘米级别的H⁻发射电流，这比从CaH₂的热解吸过程中获得的电流高约4个数量级。观察到的H⁻和OH⁻阴离子归因于它们从C12A7 - H⁻笼迁移到表面上[即，Y⁻（笼）→Y⁻（表面）→Y⁻（气相）（Y = H，OH）]。较弱的O⁻和电子发射都将源于O²⁻的解离：O²⁻（表面）→O⁻（表面）+ e⁻（表面）→O⁻（气相）+ e⁻（空间）。