PNNL-13501 - Pacific Northwest National Laboratory

Advanced Thin Film Materials Based on Functionalized Carbon Nanotube Composites
Yufei Gao (a) , Jay W. Grate, Johanes H. Sukamto, David A. Nelson, Theva Thevuthasan, Greg S. Herman
Study Control Number: PN00006/1413
Carbon nanotubes are emerging as a new, advanced material for the next century. Functionalization of these carbon
nanotubes will further enhance their potential applications and usefulness. Applications envisioned include the next
generation hydrogen storage material, durable and sensitive chemical sensors, and membranes for energy-efficient
separation of ions.
Project Description
We investigated functionalized carbon nanotube
composite materials with the aim of exploring their
chemical and physical properties. The proposed research
was based on our recently developed novel synthesis
technique for producing carbon nanotube thin films with
controlled properties, together with our expertise in metal
decoration and polymer derivatization of various surfaces.
The scope of the work encompasses fundamental studies
on the growth and modification of carbon nanotube films,
patterning, characterization of interactive properties, and
exploratory experiments to demonstrate the functionality
of these novel materials in applications such as hydrogen
storage.
Introduction
Carbon nanotubes are emerging as a new advanced
material for the next century. Because of the combination
of their high mechanical strength, tailorable electronic
properties, high surface area, light weight, and excellent
chemical and thermal stability, carbon nanotubes exhibit a
variety of potential applications ranging from hydrogen
storage, electronic nano-devices, fuel cells, and batteries.
To date, most of the fundamental research on carbon
nanotubes has been focused on their growth mechanism
and direct measurements of various physical properties.
Modifying the surfaces of carbon nanotubes with
functional materials exhibiting useful chemical and
physical properties will add a new aspect of promise for
the applications of this family of novel materials.
However, the fundamental study of such advanced
composite materials is absent in the literature, and their
tremendous potential is yet to be realized.
Approach
Following an approach similar to one described by
Li et al. (1996), support substrates for carbon nanotubes
were initially coated with a thin film of porous silica
impregnated with metal catalysts (such as, Fe, Ni, or Co).
Carbon nanotubes were subsequently grown by chemical
vapor deposition (CVD) techniques employing ethylene
as the carbon source. The resulting carbon nanotube films
were typically characterized by scanning electron
microscopy and transmission electron microscopy.
We have investigated two types of surface modifications.
First, nanoparticles of platinum were coated
electrochemically using commercial solutions. Second,
electroactive polymers (polyvinylferrocene) have been
coated on carbon nanotubes by solvent casting methods.
For hydrogen storage studies, we used an element-specific
ion-beam technique developed at this Laboratory based
on nuclear reaction analysis for determining the
concentration of absorbed hydrogen (H2).
Results and Accomplishments
Aligned and crack-free carbon nanotube films are critical
for many applications (field emission devices). We have
successfully grown aligned carbon nanotube films on
stainless steel foils as shown in Figures 1a to 1c. A
stainless steel foil was first coated with a thin film of
porous silica impregnated with iron. The carbon
nanotubes were subsequently grown on the substrate at
750ºC using ethylene as the carbon source. The cracks
seen in Figure 1a are possibly caused by cracks on the
(a) Yufei Gao and Johanes H. Sukamoto resigned from Pacific Northwest National Laboratory. Chris Aardahl assumed responsibility for
this project.
Materials Science and Technology 303