High-purity helical carbon nanotubes by trace-water- assisted chemical vapor deposition： Large-scale synthesis and growth mechanism  

作　　者：Fanbin Meng Ying Wang Qiang Wang Xiaoling Xu Man Jiang Xuesong Zhou Ping He Zuowan Zhou 

机构地区：[1]Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China [2]Zhonghao Heiyuan Research Institute of Chemical Industry, Zigong 643201, China

出　　处：《Nano Research》2018年第6期3327-3339,共13页纳米研究（英文版）

摘　　要：Helical carbon nanotubes （HCNTs） are highly desirable due to their unique geometrical elegance and inherent physical properties; however, high-efficiency synthesis of high-purity HCNTs with high yield and full elucidation of their growth mechanism remains challenging. Traditional methods to achieve the high-yield growth of HCNTs mainly focus on controlling the size of catalytic particles. Herein, we found that addition of trace water greatly benefits large-scale synthesis of HCNTs. Uniform HCNTs with - 100% purity can be obtained, and the yield of HCNTs can reach ~ 8,078% in a run of 6 h, much higher than that obtained without trace water and any of the reported yields. Experiments and theoretical simulations are performed to reveal that the trace water can react with the dangling bond on carbon, thus inhibiting the generation of amorphous species. Furthermore, the trace water can enhance the anisotropy of the catalyst surface. This results in different segregation rates of carbon atoms coming out of different crystal planes and further periodic mismatch of the graphite layers, thus leading to the formation of HCNTs. Therefore, this new and efficient method is promising for practical, large-scale production of HCNTs.Helical carbon nanotubes （HCNTs） are highly desirable due to their unique geometrical elegance and inherent physical properties; however, high-efficiency synthesis of high-purity HCNTs with high yield and full elucidation of their growth mechanism remains challenging. Traditional methods to achieve the high-yield growth of HCNTs mainly focus on controlling the size of catalytic particles. Herein, we found that addition of trace water greatly benefits large-scale synthesis of HCNTs. Uniform HCNTs with - 100% purity can be obtained, and the yield of HCNTs can reach ~ 8,078% in a run of 6 h, much higher than that obtained without trace water and any of the reported yields. Experiments and theoretical simulations are performed to reveal that the trace water can react with the dangling bond on carbon, thus inhibiting the generation of amorphous species. Furthermore, the trace water can enhance the anisotropy of the catalyst surface. This results in different segregation rates of carbon atoms coming out of different crystal planes and further periodic mismatch of the graphite layers, thus leading to the formation of HCNTs. Therefore, this new and efficient method is promising for practical, large-scale production of HCNTs.

关 键 词：helical carbon nanotubes trace water assist high yield and purity first-principles study growth mechanism 

分 类 号：TQ342.742[化学工程—化纤工业] O613.71[理学—无机化学]