Gas phase infiltration of carbon nanotubes in Ni Nanofoam via liquid injection chemical vapor deposition

Abstract

We demonstrate a new approach for improving the specific surface area of Ni nanofoam (NiNF) by exploiting its high void fraction for gas-phase infiltration of carbon nanotubes (CNTs) via liquid injection chemical vapor deposition (LICVD) process. To address the poor thermal stability of NiNF at CNT growth temperatures and low CNT nucleation density, a two-step pretreatment approach is implemented. First, a thin graphitic coating is deposited to stabilize NiNF via CH4 CVD at 550°C. Second, Fe catalyst is activated by depositing a thin layer of AlxOy (~2nm) on the graphite-coated NiNF. The infiltration of CNTs at 750°C increases the BET specific surface area of the resulting hybrid NiNF by a factor of over 20. A major appeal of this approach is that it can be utilized for tuning the structural properties of other nanostructures with relatively low temperature tolerance.