微米空心碳球串珠结构的制备与形成机理

第26卷 第2期 无 机 材 料 学 报 Vol. 26

No. 2

2011年2月

Journal of Inorganic Materials

Feb. , 2011

收稿日期:

2010-04-29; 收到修改稿日期: 2010-06-03

作者简介: 杨 涛(1981−), 男, 博士研究生. E-mail: qinming530@ 通讯联系人: 祝迎春, 教授. E-mail: yzhu@

文章编号: 1000-324X(2011)02-0139-06

DOI: 10.3724/SP.J.1077.2011.00139

微米空心碳球串珠结构的制备与形成机理

杨 涛, 祝迎春, 钱霍飞, 袁建辉, 许钫钫

(中国科学院 上海硅酸盐研究所 特种无机涂层重点实验室, 上海 200050)

摘 要: 以还原Fe 粉和活性炭为原料, 通过热CVD 法制备出微米级的空心碳球串珠结构. 利用TEM 、EDS 和多点氮吸附仪进行形貌、成分、比表面积及孔径分布表征. 串珠结构由φ(1~2)μm 的空心碳球串联而成, 长度可达十几微米. 碳球的壁厚为3~5nm 的石墨球壳结构. 所制备产物的比表面积S BET 达到306.523m 2/g, 其孔径分布在中孔范围, 峰值位于3.761nm. 微米级空心碳球串珠结构的形成机理为: 含C 的Fe 微液滴在低温区凝聚并以石墨烯片层的方式析出C, 外延于Fe 液滴形成石墨层, 与Fe 液滴构成Fe/石墨层核壳结构, 石墨球壳的收缩趋势挤压Fe 液滴沿轴向移动. 循环往复上述即形成空心串珠结构. 该结构在节能材料、药物、染料和催化剂等的载体材料、储氢、储能等方面可能具有良好的应用前景.

关 键 词: 微米级; 串珠结构; 空心碳球; 比表面积; 孔径分布 中图分类号: TQ127 文献标识码: A

Synthesis and Mechanism of Micron-level Hollow Carbon Rosary Structures

YANG Tao, ZHU Ying-Chun, QIAN Huo-Fei, YUAN Jian-Hui, XU Fang-Fang

(The Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China)

Abstract: Using reduced iron powder and activated carbon as starting materials, micron-level hollow carbon ro-sary structures were synthesized by thermal CVD method. Their morphology, composition and specific surface area and pore-size distribution of the product were characterized by TEM, HRTEM, EDS and N 2 adsorption apparatus. With dozens microns in length and 1−2 μm in diameter, the rosary structures were formed by hollow carbons. The hollow carbon actually was graphite shells with 3−5 nm in thickness. The specific surface area S BET of the product was up to 306.523 m 2/g, and the pore-size was mainly distributed in the mesoporous range, whose peak mark at 3.761 nm. The mechanism of the product can be described as follows, carbon was precipitated in the form of gra-phene pieces at lower temperature by iron/C droplet, which epitaxially grew on iron/C droplet and formed graphite shells. The graphite shells and iron/C droplet constituted shell/core structures. The contraction trend of graphite shells squeezed the iron/C droplet along the axial direction. The processes above repeated and the carbon rosary structures formed. The product may have potential applications in the energy-saving materials, supporter materials for drugs/dyes/catalysts, hydrogen/energy storage materials.

Key words: micron-level; rosary structure; hollow carbon; specific surface area; pore-size distribution

由于特殊的电子结构, 碳是一种用途很广的化学元素. 二十多年来, 随着制备技术和测试技术的不断发展和改进, 除了同位素结构的石墨和金刚石, 还发现了碳的其它新奇结构, 如足球烯[1]、纳米

管[2]、石墨洋葱[3]、石墨环[4]、石墨锥[5]、串珠结 构[6-7]等等. 碳纳米管的发现, 对电子学和力学研究领域产生了深远的影响. 碳纳米结构作为一种极具吸引力的电极材料, 由于其化学稳定性、低密度、