S.A.M. Zobir

Synthesis and nucleation-growth mechanism of almost catalyst-free carbon nanotubes grown from Fe-filled sphere-like graphene-shell surface

This finding focuses on the optimization of synthesis time for the transformation of Fe-filled spherical-like graphene shell (GS) to almost catalyst-free carbon nanotube (CNT) structure using two-stage catalytic chemical vapor deposition apparatus. The camphor oil and ferrocene were used as carbon precursor and catalyst respectively, following the variety growth of graphene-family nanomaterials for 2, 4, 6, 8, 10, 30, and 60 min at 800°C synthesis temperature. The graphene-family nanomaterial properties were characterized using field emission scanning electron microscope, high resolution transmission electron microscope, micro-Raman spectrometer, thermogravimetric, and carbon-hydrogen-nitrogen-sulfur/oxygen (CHNS/O) analyzer. The result of field emission scanning electron microscopy analysis reveals that the CNTs were observed with high aspect ratio at 60-min synthesis time. The dependence of integrated intensity ratio of D-band and G-band (ID/IG) presented that ID/IG ratio sharply decreases with longer synthesis time. At higher synthesis time, thermogravimetric and CHNS/O analysis of CNT can obviously improve with decreases of non-carbonaceous material and transition metal catalyst. The nucleation-growth model of Fe-filled spherical-like GS to almost catalyst-free CNT has been highlighted to explain the change in growth mode.

Raman spectroscopic study of carbon nanotubes prepared using Fe/ZnO-palm olein-chemical vapour deposition

Multiwalled carbon nanotubes (MWCNTs) were synthesized using Fe/ZnO catalyst by a dual-furnace thermal chemical vapor deposition (CVD) method at 800-1000°C using nitrogen gas with a constant flow rate of 150 sccm/min as a gas carrier. Palm olein (PO), ferrocene in the presence of 0.05M zinc nitrate, and a p-type silicon wafer were used as carbon source, catalyst precursor, and sample target, respectively. D, G, and G′ bands were observed at 1336-1364, 1559-1680, and 2667-2682 cm-1, respectively. Carbon nanotubes (CNTs) with the highest degree of crystallinity were obtained at around 8000?C, and the smallest diameter of about 2nm was deposited on the silicon substrate at 1000°C.

The Effect of Precursor Vaporization Temperature on the Growth of Vertically Aligned Carbon Nanotubes Using Palm Oil

Carbon nanotubes (CNTs) were fabricated from palm oil using the thermal chemical vapor deposition technique utilizing a two furnace system. The effect of precursor vaporization temperature of the first furnace, in the range of 300-600°C was systematically studied with the synthesis temperature (second furnace) fixed at 750°C for a total time of 30 min. The samples were characterized using field emission scanning electron microscopy and micro-Raman spectroscopy. CNTs of various packing densities and diameters were synthesized with the varying precursor vaporization temperature. Based on micro-Raman measurements nanotube defect level and the presence of SWCNT were dependent on the vaporization temperature. Vertically aligned CNTs (VACNTs) were found to grow within the vaporization temperature range of 400-500°C, with well graphitized and higher yield obtained at 450°C with excellent lateral alignment, uniform nanotubes diameter (~15 nm), orientation and distribution within the CNT bundles. At vaporization temperatures of 300-350°C and 500-600°C, lower growth rate, bigger nanotubes diameter and higher ID/IG ratio were observed which indicated lower nanotubes quality that produced at both temperature ranges.

Electrical properties of carbon nanotubes synthesis by double furnace thermal-CVD technique at different temperatures on porous silicon template

Multiwalled Carbon Nanotubes (MWCNs) were synthesized using double-furnace thermal chemical vapor deposition technique at 700 – 900 °C on porous silicon nanostructure (PSiNs). Palm oil used as a carbon natural source, ferrocene as a catalyst and nitrogen gas as a carrier gas. The precursor were vaporized at 475 °C carried by nitrogen gas which flow at constant rate 150 sccm/min. Carbon nanotubes characterized by using Raman Spectroscopy and field emission scanning electron microscopy (FESEM) to check its structure and crystallites before tested with I-V probe. Au contact used as a metal contact deposited on CNTs layer. Carbon nanotubes (CNTs) with uniform diameter were found grown on porous silicon for each temperature used. Based on micro-Raman spectroscopy result, the peak of carbon nanotubes (around 1 300 to 1 600 nm) was detected. The I-V characteristic of CNTs deposited had different profile when deposited at different temperature.

Structural and Thermal Properties of ACNT by Modified Deposition Method: Growth Time Approach

The knowledge of fabrication method plays an important role in the preparation of aligned carbon nanotubes (ACNT) from natural hydrocarbon feedstock. Here ACNT were successfully synthesized by two-stage catalytic chemical vapor deposition method using organic oil (camphor oil) as a precursor. Synthesis was carried out at a fixed growth temperature of 800 °C and in different growth time: 10, 20, 30, 40, 50 and 60 minutes. The optimized condition for the growth of ACNT produced a small amount of by-product amorphous carbon and highly uniform crystal structure. The experimental results demonstrated that formation ACNT is also dependent on the growth time. The nanotubes were characterized by field emission scanning electron microscopy and micro-Raman spectroscopy. Thermal properties were evaluated by thermogravimetric analysis.

Electrical Contact of Au with CNTs Deposited at Different Deposition Temperatures on Silicon Substrate

In this work, the electrical properties of carbon nanotubes were deposited on silicon substrate at different temperatures studied. CNTs were deposited on silicon at temperature 700 to 850 0C by using double-furnace thermal chemical vapor deposition technique. Carbon nanotubes with diameters of 20 to 30 nm were successfully synthesized on a silicon substrate. In this system, carbon nanotubes were grown directly on the p-type silicon. The samples were characterized using field emission scanning electron microscopy and micro-Raman spectroscopy. Based on micro-Raman spectroscopy result, the peak carbon nanotube (around 1 300 to 1 600 nm) was detected. Good electrical contact produced when Au sputter on CNTs characterized by I-V probe. Samples CNTs produced at 850 OC possess good conducting compare to other.

The Structural Properties of Carbon Nanotubes Grown on Porous Silicon-Based Materials by Thermal Chemical Vapor Deposition Method

In this paper, carbon nanotubes on porous silicon substrate were developed in order to get high quality nanotubes for various kind of application. CNTs were deposited on porous silicon nanostructures (PSiN) at 750 0C on porous silicon by using double-furnace thermal chemical vapor deposition technique. Align carbon nanotubes with diameters of 15 to 30 nm were successfully synthesized on a porous silicon substrate. In this system, carbon nanotubes were grown directly on the p-type porous silicon surface at 750 0C for a total time of 30 minutes. The samples were characterized using field emission scanning electron microscopy and micro-Raman spectroscopy. Align carbon nanotubes (ACNTs) bundle with uniform diameter (~20 nm) were found grown on porous silicon at certain area. Based on micro-Raman spectroscopy result, the peak of silicon at ~520 nm and peak of carbon nanotube (around 1 300 to 1 600 nm) was detected.

Synthesis of Carbon Nanotubes Using Zinc Nitrate as a Catalyst by Aerosol-Assisted Catalytic Single Furnace CVD

Carbon nanotubes were synthesized from the aerosol-assisted catalytic CVD method using palm oil as the precursor and 0.05M zinc nitrate solution as the catalyst. The deposition temperature of the single furnace aerosol-assisted catalytic CVD ranged from 750 to 950 oC. The samples were then characterized using field emission scanning electron microscope (FESEM), Raman spectroscopy and thermogravimetric analysis (TGA). CNTs with different diameters and distribution were produced at certain deposition temperature and amorphous carbons were also present in the samples.

Properties of Amorphous Carbon Microspheres Synthesised by Palm Oil‐CVD Method

Amorphous carbon microspheres were synthesized using a dual‐furnace chemical vapour deposition method at 800–1000° C. Palm oil‐based cooking oil (PO) and zinc nitrate solution was used as a carbon source and catalyst precursor, respectively with PO to zinc nitrate ratio of 30:20 (v/v) and a silicon wafer as the sample target. Regular microsphere shape of the amorphous carbons was obtained and a uniform microsphere structure improved as the carbonization temperature increased from 800 to 1000° C. At 800° C, no regular microspheres were formed but more uniform structure is observed at 900° C. Generally the microspheres size is uniform when the heating temperature was increased to 1000° C, but the presence of mixed sizes can still be observed. X‐ray diffraction patterns show the presence of oxide of carbon, ZnO phase together with Zn oxalate phase. Raman spectra show two broad peaks characteristic to amorphous carbon at 1344 and 1582 cm−1 for the D and G bands, respectively. These bands become more prominent...