物理化学学报 >> 2009, Vol. 25 >> Issue (09): 1713-1720.doi: 10.3866/PKU.WHXB20090828

研究论文 上一篇    下一篇

微孔晶体材料C12A7-Cl-的表面氯负离子发射性能和机理

孙剑秋, 宋崇富, 宁珅, 林少斌, 李全新   

  1. 中国科学技术大学化学物理系, 生物质洁净能源实验室, 合肥 230026|阜阳师范学院化学系, 安徽 阜阳 236041
  • 收稿日期:2009-04-13 修回日期:2009-05-18 发布日期:2009-09-03
  • 通讯作者: 李全新 E-mail:liqx@ustc.edu.cn

Features and Mechanism of Chlorine Anion Emission from Microporous Crystal C12A7-Cl- Surface

SUN Jian-Qiu, SONG Chong-Fu, NING Shen, LIN Shao-Bin, LI Quan-Xin   

  1. Laboratory of Biomass Clean Energy, Department of Chemical Physics, University of Science &Technology of China, Hefei 230026, P. R. China|Department of Chemistry, Fuyang Normal College, Fuyang 236041, Anhui Province, P. R. China
  • Received:2009-04-13 Revised:2009-05-18 Published:2009-09-03
  • Contact: LI Quan-Xin E-mail:liqx@ustc.edu.cn

摘要:

利用飞行时间质谱(TOF-MS)观测到氯负离子从合成的微孔晶体材料C12A7-Cl-(11CaO·7Al2O3·CaCl2)表面发射出来, 详细研究了C12A7-Cl-的发射特性, 包括发射强度分支比、温度效应、电场效应和表观活化能. 在我们的检测范围内从C12A7-Cl-表面发射的离子中绝大部分是氯负离子(最大强度分支比为98%), 此外还有弱的氧负离子和电子发射. 各种离子的绝对发射电流强度都随着表面温度升高或引出电场强度的增加而显著增强, 随着引出电场强度从200增加到1200 V·cm-1, 氯负离子发射的表观活化能从180.9 kJ·mol-1减小到110.0 kJ·mol-1. 氯负离子和C12A7-Cl-表面之间的结合能大约是228 kJ·mol-1. 研究了氯负离子的发射稳定性, 并且应用一种电化学注入法, 以获得持续的氯负离子发射. 基于上述实验还讨论了氯负离子的形成和发射机理. 目前的方法可望被用于发展氯负离子储存/发生器.

关键词: 氯负离子, C12A7-Cl-, 发射特性, 电化学注入

Abstract:

Chlorine anion (Cl-) emission from the synthesized microporous crystal surface of C12A7-Cl- (11CaO·7Al2O3·CaCl2) was observed by time-of-flight mass spectrometry (TOF-MS). We investigated the emission features of C12A7-Cl- (including branching ratios of emission intensity, temperature effect, electric field effect, and apparent activation energy) in detail. The anionic species emitted from the C12A7-Cl - surface were dominant by Cl- anions (maximum branching ratio of intensity: 98%) while a weak O- anion emission and electron emission were also observed. The emission current densities of the anionic species were significantly enhanced by the increase of sample surface temperature or extraction electric field strength. The apparent activation energies for the Cl- emission decreased from 180.9 to 110.0 kJ·mol-1 as the extraction electric field strength increased from200 to 1200 V·cm-1. The binding energy between the Cl- anion and the C12A7-Cl- surface was about 228 kJ·mol-1. The stability of the Cl- emission was also investigated and an electrochemistry implantation method was adopted to obtain a sustainable Cl- emission. We also discussed the formation and emission mechanism of Cl- anions based on the above investigations. This method may be potentially useful to develop a reservoir or generator of Cl- anions.

Key words: Chlorine anion, C12A7-Cl-, Emission feature, Electrochemistry implantation

MSC2000: 

  • O646