“Smart poisoning” of Co/SiO2catalysts by sulfidation for chirality-selective synthesis of (9,8) single-walled carbon nanotubes

• DOI: 10.1039/c6nr05938d
• Publication Date: 2016-09-09T11:24:43Z
• Authors: Yang Yuan; H. Enis Karahan; Cansu Yıldırım; Li Wei; Özgür Birer; Shengli Zhai; Raymond Lau; Yuan Chen
• Keywords: Sulfidation; Chirality; Carbon fibers

The chirality-selective synthesis of relatively large (diameter > 1 nm) single-walled carbon nanotubes (SWCNTs) is great interest for a variety practical applications, but only few catalysts are available so far. Previous studies suggested that S (compounds) can enhance the chirality-selectivity Co in SWCNT synthesis, however, mechanism behind not fully understood, and no tailorable methodology has yet been developed. Here, we demonstrate facile approach to achieve SWCNTs by sulfidation-based poisoning silica-supported using mixture H2S H2. UV-vis-NIR, photoluminescence, Raman spectroscopy results together show resulting have narrow diameter distribution around 1.2 nm, (9,8) an abundance ∼38% among semiconducting species. More importantly, yield achieved sulfided catalyst (2.5 wt%) similar nonsulfided one (2.7 wt%). characterization X-ray diffraction, photoelectron spectroscopy, fluorescence, H2 temperature-programmed reduction shows sulfidation leads formation Co9S8 nanoparticles. However, nanoparticles reduced back regenerate metallic during SWCNTs, which maintain high yield. In this process, seemingly intermediate production with size distribution. Due fact step improves quality end-product rather than hampering growth coined process developed as "smart poisoning". This study reveals beneficial role selective also presents promising method create activity scalable synthesis.