Conformal chemical vapor deposition of B₄C thin films onto carbon nanotubes

The unique attributes of carbon nanotubes (CNTs) establish them as the preferred material for fabricating sophisticated membrane architectures. However, CNT membranes are also susceptible to degradation under harsh environmental conditions, necessitating protective measures to maintain their functionalities. This study presents deposition of boron carbide (B₄C) thin films as protective coatings on CNT membranes using chemical vapor deposition. Electron microscopy shows that B₄C films were uniformly deposited on the CNTs. Raman spectroscopy shows the preservation of the G and D bands, with a notable stability in the RBM bands, while XPS measurements show sp² hybridized C-C bonds and an additional shoulder characteristic of the deposited B₄C film. This suggests that the CVD process does not degrade the CNTs, but merely adds a layer of B₄C to their outer surface. This deposition process also allows for precise control over the membrane's pore size, offering the potential to fine-tune the properties of CNT membranes.