CNFs and CNTs grow on a substrate by several methods. One of the most commonly used methods is catalytic chemical vapor deposition.Some times from SEM images it becomes very difficult to differentiate between them. Is there any other techniques available to differentiate them without any further confusion.
Are they both on the same substrate?
If not then try micro-Raman you can discriminate the two.
If they are on the same substrate, it will be harder, but I guess that a thermal treatment of the wafers would work since the CNFs would have a lower degradation temperature than the CNTs.
No they are not on same substrate. I have carried out Raman analysis for CNF samples and got two characteristic peaks at approximately 1350 and 1590 cm-1, respectively. I do not have that much idea for CNT samples. Will I get some additional peaks after performing micro Raman analysis of CNT samples.
Hi,
Secondary electron SEM mainly gives morphological information. Therefore CNT and CNF will look similar in SEM images as fibrous materials.
If you can do high resolution TEM, then it will be more straightforward. CNTs generally have concentric tubular atomic planes while CNF, I believe, will be stacked cup or with atomic planes perpendicular to the fiber direction.
Apropos micro Raman, I have not tested with CNF so I can't talk about it. CNTs are also graphitic nanomaterials, similar to CNFs, and will generally give 2 most dominant peaks, which are D peak (about 1350 cm-1, depends on the excitation light) and G peak (about 1580 cm-1), similar to your CNFs. They have very similar nature anyway. Additional peaks you may see are D' peak at ~1600 cm-1, and second order peaks somewhere in the range 2700-3200 cm-1.
Regards,
KC
From Raman, it s pretty difficult to distinguish between CNF and MWCNT.. there are far too many variables in MWCNT like number of walls, their orientation, crystallinity, catalystimpurities etc. which affects location and intensity of D and G peaks.
Best option is HR-TEM
I suggest you to first opt for High resolution TEM. Low temperature Raman may work.
High resolution TEM will give you an unambiguous result.
CNFs look like stacked cup - Herringbone structure.
CNTs look like concentric cylinders.
. The main difference between CNTs and CNFs is the orientation of graphitic structure along the filament axis. As the graphitic layers of CNTs are parallel to the axis while it is out of the plane in case of CNFs. The exposed surface of CNFs mainly consists of prismatic planes (node and inter node) and possess high adsorption capacity when compared to the graphite basal planes of the CNT
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