【作者】 杨烽； 李彦；

【Author】 Feng Yang;Yan Li;College of Chemistry,Peking University;

【机构】 北京大学化学与分子工程学院；

【摘要】 单壁碳纳米管的原位成核研究对深入了解碳纳米管的生长机制具有重要意义。我们利用球差矫正环境电镜和原位EXAFS研究了单质钴催化剂和Co₇W₆催化剂上碳纳米管的成核行为,发现Co₇W₆催化剂在700-1100℃时保持稳定的化学组成和晶态结构,原子台阶及原子间距稳定不变,并可以清晰地观察到碳纳米管的成核;而单质钴则完全不同,钴会熔融并部分碳化,而单质钴和碳化钴的共存是碳纳米管成核和生长必须的条件,可以观察到碳在催化剂中的溶解和析出。这些研究使我们深化了对碳纳米管催化成核过程机制的认识,对碳纳米管的可控生长具有重要指导意义。更多还原

【Abstract】 Revealing the catalyst structure in the working environment is crucial for understanding the controlled growth mechanism of single-walled carbon nanotubes（SWNTs）. We used the aberration-corrected environmental transmission electron microscope（ETEM） combined with electron energy loss spectroscopy to detect the Co₇W₆ catalyst structure and composition in the reaction environment. With the quantitative analysis of high-resolution image combined with simulation, we showed that theCo₇W₆ catalyst structure keep stable with carbon feeding at 700-1100 ℃. Carbon caps were clearly observed to nucleate from the Co₇W₆ nanocrystals from ETEM. We also established in situ synchrotron X-ray absorption spectroscopy operated in the atmospheric-pressure CVD and demonstrated the stable local coordination structure of Co₇W₆. No carbides or carbon diffusion induced structural change was observed from these in situ characterization. It reveals that Co₇W₆ catalysts act as the stable structuretemplate for the chirality controlled growth of SWNTs.更多还原