Influence of Different Defects in Vertically Aligned Carbon Nanotubes on TiO2 Nanoparticle Formation through Atomic Layer Deposition.
The chemical inertness of carbon nanotubes (CNT) requires some degree of "defect engineering" for controlled deposition of metal oxides through atomic layer deposition (ALD). The type, quantity, and distribution of such defects rules the deposition rate and defines the growth behavior. In this work, we employed ALD to grow titanium oxide (TiO2) on vertically aligned carbon nanotubes (VACNT). The effects of nitrogen doping and oxygen plasma pretreatment of the CNT on the morphology and total amount of TiO2 were systematically studied using transmission electron microscopy, Raman spectroscopy, and thermogravimetric analysis. The induced chemical changes for each functionalization route were identified by X-ray photoelectron and Raman spectroscopies. The TiO2 mass fraction deposited with the same number of cycles for the pristine CNT, nitrogen-doped CNT, and plasma-treated CNT were 8, 47, and 80%, respectively. We demonstrate that TiO2 nucleation is dependent mainly on surface incorporation of heteroatoms and their distribution rather than structural defects that govern the growth behavior. Therefore, selecting the best way to functionalize CNT will allow us to tailor TiO2 distribution and hence fabricate complex heterostructures.
Department of Materials, Federal University of Rio Grande do Sul , Porto Alegre, RS 90040-060, Brazil.|Department of Aeronautics and Astronautics, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
Luiz
L
Acauan
Department of Materials, Federal University of Rio Grande do Sul , Porto Alegre, RS 90040-060, Brazil.|Department of Chemical Engineering, Federal University of Rio Grande do Sul , Porto Alegre, RS 90040-060, Brazil.
Anna C
AC
Dias
Institute of Physics, Federal University of Rio Grande do Sul , Porto Alegre, RS 90040-060, Brazil.
Marcelo B
MB
Pereira
Institute of Physics, Federal University of Rio Grande do Sul , Porto Alegre, RS 90040-060, Brazil.
Flavio
F
Horowitz
Department of Materials, Federal University of Rio Grande do Sul , Porto Alegre, RS 90040-060, Brazil.
Carlos P
CP
Bergmann
atomic layer deposition; defects; nitrogen-doped carbon nanotubes; plasma treatment; titanium oxide; vertically aligned carbon nanotubes