2. Experimental Section
2.1
Synthesis of SCNTs
Pristine CNTs were prepared by a previously-reported chemical vapor
deposition process,23,24 using a
FeMo/Al2O3 catalyst. As a simplified
synthesis process, SCNTs were prepared in a quartz fixed bed reactor
using a SO2 and N2 mixture as S source.
In a typical run, CNTs (5 g) were added into the vertical quartz reactor
and heated to 900 ℃ in an Ar flow (0.4 L/min). Then, a gas mixture (0.1
L/min) containing 84 wt% N2 and 16 wt%
SO2 was introduced and maintained for 30 min. After
cooled to room temperature in Ar flow, the product was collected and
labeled as SCNT-SO2. As a control sample, SCNTs were
also prepared by a post-processing using MgSO4 as S
source,22 labeled as SCNT-M.