Mohd Warikh Abd Rashid

X-Ray and Morphological Characterization of Al-O Thin Films Used for Vertically Aligned Single-Walled Carbon Nanotube Growth

Al oxide (Al-O) films used as catalyst-support layer for vertical growth of carbon nanotubes (CNTs) were characterized by means of X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission, and scanning electron microscopies (TEM and SEM). EB-deposited Al films (20 nm) were thermally-oxidized at 400 o C (10 min, static air) to produce the surface structure of Al-O. The Al-O was found amorphous and after the incorporation with Co catalyst, the grown CNTs were twisted together before vertically grown. The prepared Al-O surface is an electron-acceptor-dominated (oxygen-rich) surface where the formation of active catalyst could be enhanced to promote the vertically aligned CNT growth.

A simple and room temperature sol–gel process for the fabrication of cobalt nanoparticles as an effective catalyst for carbon nanotube growth

Cobalt catalyst thin films were prepared on silicon wafers using a spin coating process. The detailed structural characteristics of the cobalt films/particles and synthesized carbon nanotubes were studied using X-ray analysis, high resolution electron microscopy, and Raman spectroscopy. The thickness of the catalyst thin films can be controlled by controlling the spin coating parameter, and the thickness of the films can be reduced by increasing the spin speed. Cobalt catalyst particles can be achieved by post-heat treatment within the range of 450–600 °C. However, increasing the post-heat treatment temperature may lead to larger particle formation. The optimum values of thin film thickness and particle size were 12.1 nm at 8000 rpm and 10.6 nm at 450 °C, respecively. The study also demonstrated that single-walled carbon nanotubes could be grown from cobalt catalyst particles via catalytic chemical vapor deposition of ethanol.

Electrophoretic Deposition and Heat Treatment of Steel-Supported PVDF-Graphite Composite Film

Polymeric poly (vinyliden fluoride) (PVDF) is nontoxic. It possesses a better mechanical flexibility and requires a lower synthesis temperature, as compared to the piezoceramic counterparts. In order to achieve a competitive advantage against the current piezoelectric sensor, graphite could replace a more expensive silver-palladium as the electrodes for the piezoelectric PVDF. This paper reports the preliminary results on the synthesis of steel-supported graphite-PVDF/PVDF/graphite-PVDF composite films using the two-step process, consisted of the electrophoretic deposition (EPD) and heat treatment. The composite films were characterized by means of the optical microscopy, scanning electron microscopy, X-ray diffraction and differential scanning calorimetry. The heat treated graphite-PVDF electrode deposited by EPD provides adequate mechanical strength for the subsequent depositions of pure PVDF layer and the second layer of graphite-PVDF composite electrode. However, the final heat treatment stage did not eliminate the fine and large cracks of the composite film, which might be attributed to high residue stresses and weak bonding between graphite and PVDF particles in the post-heat treated composite films. Nevertheless, the increase in final heat treatment temperature of the composite film at Stage 3 improved the graphite and PVDF grain alignment, as well as its crystallinity.