Systematic investigation of the catalyst composition effects on single-walled carbon nanotubes synthesis in floating-catalyst CVD

Abstract

Enormous technological promise of single-walled carbon nanotubes (SWCNTs) can only be harnessed with the premise of controllable synthesis of SWCNTs, where catalyst composition thermodynamically plays a vital role. Herein, we have systematically investigated the effects of catalyst composition on SWCNTs synthesis, using a novel floating-catalyst chemical vapor deposition (FCCVD) system, consisting of catalyst synthesis via spark generator, FCCVD reactor and a real-time monitor of catalysts and SWCNTs. We synthesized SWCNTs from both monometallic (Fe, Co, Ni), bimetallic (Co-Ni, Co-Fe) catalyst particles and kinetically optimized yield and performance of SWCNTs films. We found that the highest yield of SWCNTs from Fe is 15 times as that of Ni SWCNTs and the Co-Ni SWCNTs film possesses best opto-electronic performance. Interestingly, the mean diameter of SWCNTs was found related to the catalyst particle size distributions, but not composition. Moreover, detailed atomic structures determination revealed that SWCNTs from Fe and Co have a wide chirality distribution spanning from zig-zag to armchair edges. However, Co-Ni SWCNTs have comparatively narrower chirality distribution having 71% SWCNTs in the chiral angle of 15–30°. Our results indicate that catalyst composition can efficiently tune yield and characteristics of SWCNTs, but it does not dramatically shift chirality of FCCVD SWCNTs.