Sol Gel Process Of Cobalt Nanopracticles Preparation As Effective Catalyst For CNT Growth Performance

Carbon nanotube (CNT) is a well known structure that has extraordinary properties and widely used in many application. The presence of metal catalyst is needed for CNT growth by CVD technique. The properties of as-grown CNT is depends on the properties of metal catalyst. The aim of this project was to produce cobalt (Co) catalyst by spin coating process for carbon nanotube (CNT) growth. It was targeting to study the catalyst thin film formation by using solution process, analyze the catalyst nanoparticles transformation from the deposited thin film and confirm the structural properties of as-grown CNT by Raman spectroscopy. This project was divided into two major parts. The first part was catalyst preparation and the second part was CNT growth. The Co catalyst was prepared by spin coating and heat treatment process. The spin speed of spin coating was varied from 6500 rpm to 8000 rpm with 500 rpm interval and spinning duration of 60 s. The post-heat treatment temperature was varied from 450 ⁰C to 600 ⁰C with interval of 50 ⁰C and heating duration of 10 minutes. The Co catalyst nanoparticles formed after heat treatment process then being used for CNT growth by alcohol catalytic CVD (ACCVD) technique. The CVD processing temperature was varied in range of 650-750 ⁰C with 25 ⁰C interval. The CVD processing time was fixed for 15 minutes. The Co catalyst and its nanoparticles were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) while the structural properties of the as-grown CNT was studied by Raman spectroscopy. The thickness of Co catalyst thin film was decreasing by the increasing of spin speed. Based on four varied value of spin speed; 6500, 7000, 7500 and 8000 rpm, the optimum spin speed with smallest thickness of Co catalyst thin film, 12.1 nm, was at 8000 rpm. Besides, the average size of Co nanoparticle was increased by the increasing of post-heat treatment temperature. The optimum temperature was found at 450 ⁰C with 10.64 nm average size of Co nanoparticles. The Co catalyst thin film was confirmed by XRD and XPS analysis to have CoO compound structure while the Co catalyst nanoparticles was in Co3O4 structure. Then, 700 ⁰C was found to be the optimum CVD processing temperature for the CNT grown on spin coated Co catalyst nanoparticles with the highest IG/ID ratio of 6.398. Additionally, the presence of SWCNT structure was confirmed by the presence of RBM peak in range of 100-400 cm-1 Raman shift measured by Raman spectroscopy. The measured SWCNT tube diameters were less than 1.5 nm. Hence, it can be concluded that the thickness of Co catalyst thin film can be controlled by controlling the spin speed of spin coating. Optimum post-heat and CVD processing temperature is crucial for Co catalyst nanoparticles formation and obtaining good quality of CNT. The as-grown CNT in this project has high potential in electronic device application due to the smaller SWCNT tube diameter and good quality

Synthesis of Fe catalyst nanoparticles by solution process towards carbon nanotube growth

The iron catalyst nanoparticles were prepared on silicon wafers by solution process, which first spins coat the solution of iron (III) nitrate nonahydrate and colloidal solution, and then are heated to obtain the formation of iron nanoparticles. The effects of different spin speed and heat treatment parameters during the solution process were investigated. As a result, the smallest thickness of the Fe catalyst thin films is 78 nm, and the smallest Fe catalyst nanoparticles, i.e. 9.67 nm, were obtained at the highest spin speed of 8000 rev min-1 and 500oC. The uniformity of the thin films was also found to increase with increasing spin speed. The particle and thickness analysis was performed by means of field emission scanning electron microscopy

Systematic review of catalyst nanoparticles synthesized by solution process: towards efficient carbon nanotube growth

Nano-field research has been expanded rapidly since those tiny materials such as carbon nanotubes (CNTs), cobalt catalyst and iron catalyst can give huge impact to the application products with their extraordinary properties. The scientific discovery of these materials can be defined as a magic key to solve the raw materials shortage and unlock the limitation performance of the devices. CNTs have been found to be one of the new nanomaterials that can improve different kind of devices’ performance. CNT can be grown on the substrates with the presence of active metal catalysts. Since small metal catalyst particles (diameter <10 nm) are crucial in growing CNTs, the deposition method of metal catalyst on the substrates has been studied. The optional processes using solutions to produce catalyst nanoparticles will be discussed in this review. Sol–gel process along with spin coating is the most suitable deposition method with low cost of production and the easiness to control particle size deposited on the substrates

Control of Cobalt Catalyst Thin Film Thickness by Varying Spin Speed in Spin Coating towards Carbon Nanotube Growth

Cobalt (Co) catalyst thin film is an active metal catalyst that can be very helpful to grow carbon nanotubes (CNTs). The catalyst thin films were prepared on silicon wafers by spin coating the solution of cobalt acetate tetrahydrate and ethanol. The effects of different spin speed parameter during the spin coating process were investigated. The findings showed that the optimum thickness of the Co catalyst thin films, i.e., 12.1 nm, was obtained at the highest spin speed of 8000 rpm. The uniformity of the thin films was also found to increase with increasing spin speed. The study also demonstrated that single-walled carbon nanotubes could be grown from Co catalyst particles after the catalytic chemical vapor deposition of ethanol. The particle and thickness analysis, as performed by means of FESEM while the existence of CNTs, was performed by Raman spectroscopy

Direct Observation Of Graphene During Raman Analysis And The Effect Of Precursor Solution Parameter On The Graphene Structures

Controlling the precursor solution parameter in preparing active catalyst film is critical in sol-gel process. The aim of this work is to validate the precursor solution parameter that affects the structural properties of graphene. Active Co3O4 film was prepared using precursor solution from cobalt acetate tetrahydrate in two different concentrations; 0.025 M and 0.05 M. One batch of the precursor solution was directly spin coated onto the substrate's surface meanwhile the second batch was kept for 4 days aging process. The studied spin speeds were 2000 rpm and 6000 rpm, and spin coated for 60 s. The active Co3O4 film was achieved by annealing at 450 °C and the graphene was grown at 900 °C of chemical vapor deposition (CVD) processing temperature for 5 min with the presence of ethanol as the carbon feedstock. The structural properties and morphology of the as-grown graphene synthesized from active Co3O4 film were characterized by Raman spectroscopy, optical microscope, and field emission scanning electron microscope (FESEM). The results demonstrated that concentration of precursor solution and the aging process affected the performance of the as-grown graphene. Agglomerates were formed in sample with 0.05 M of Co acetate tetrahydrate, however it was found that the Raman peaks intensity increased as compared to the 0.025 M sample. The precursor with 0.05 M has an acceptable chemical stability though aged for 4 days and contributed to the graphene growth. The spin coating speed was found not to affect the graphene growth at all. For aging effect, concentration 0.025 M shows unstable condition as compared to concentration 0.05 M when the precursor solution was aged for 4 days. Nonetheless, for the quality of the as-grown graphene, the ratio of Raman 2D-band over G-band intensities was less than 1.0, indicated that the graphene was in multi-layer form

Parametric Study of Spin Coating Technique to Prepare Catalyst Nanoparticles

The formation of nanosized catalyst particles from Fe- and Co-based functional solution is very important for carbon nanotube growth. The most critical factor is the uniformity of catalyst thin film thickness, because roughened surface may directly affect the size of the particles. In order to achieve good uniformity, there are few spin coating parameter need to be controlled during the spin coating process; e.g., volumes of solution, rotation speeds, and spin time. Appropriate temperature during heat treatment is another critical factor for the nanoparticle formation due to its ability to develop nanoparticle dimension consistent to that of original thickness

Active Cobalt Catalyst for Carbon Powder Growth: Sol-gel Process and Alcohol Catalytic CVD Technique

The unique properties of carbon nanotubes trigger a lot of ideas to study the ability of the material in many fields. Experimental: The research started with the preparation of cobalt catalyst by using the sol-gel method, which used cobalt acetate tetrahydrate and 2-amino ethanol solvent, followed by the actual growth of carbon nanotube by using the prepared catalyst in alcohol catalytic CVD. Results: The crystal structure, microstructure, and size of particles of the resulting cobalt-based powders were characterized by using X-ray Diffraction, Optical Microscopy, and Particle Size Analyzer, followed by, carbon nanotube growth at 700, 750, 800, and 850°C, where other parameters were fixed in order to determine the effect of CVD processing and temperature on the quality of resulting carbon-based materials. The graphitic structure of the carbon-based materials was analyzed by using Raman Spectroscopy. Conclusion: It was found that the optimum CVD processing temperature was 850°C with IG/ID ratio of 1.05

Study of mechanical and flammability properties of polypropylene/microcrystalline cellulose composites filled with nano-sized aluminium hydroxide (ATH) particles

The mechanical and flame properties of polypropylene/ microcrystalline cellulose (MCC) composites containing different loading of aluminium hydroxide (ATH) nanoparticles from 3 to 20wt% was studied. Maleic anhydride grafted polypropylene (MAPP) was used as a coupling agent in the composites. The mechanical properties of PP/MCC composites were characterized by tensile and impact tests while the flame properties were evaluated by UL-94 and oxygen index tests. It was shown that the addition of ATH improved the mechanical and flame resistance properties PP/MCC composites, mainly in the composites with MAPP. Fracture surface observations in samples with MAPP show better dispersion and adhesion of fillers (MCC and ATH). Flame retardancy also enhanced along with the ATH loading

Active phase of cobalt oxide (Co3O4) as a promising catalyst for graphene growth by alcohol catalytic chemical vapor deposition

The presence of active catalyst during graphene growth by alcohol catalytic chemical vapour deposition is a compulsory. This study is aimed to validate the effect of annealing temperature for the formation of active cobalt oxide (Co3O4) film on the graphene growth by alcohol catalytic chemical vapour deposition technique. Active Co3O4 film was prepared on silicon wafers by sol-gel process, using cobalt acetate tetrahydrate as the precursor compound and absolute ethanol as the solvent. Them active Co3O4 phase was achieved by annealing process at 450, 500, 550 and 600 °C. The graphene is grown from active Co3O4 film under 900 °C of chemical vapor deposition (CVD) processing temperature for 5 minutes. The obtained Co3O4 was characterized by x-ray diffraction and Raman spectroscopy. The as-grown graphene from active Co3O4 film annealed at 450 ⁰C was characterized by Raman spectroscopy and field emission scanning electron microscope (FESEM). The results demonstrate that spinel type cubic structure of Co3O4 could be produced at the varied annealing temperatures but the optimum XRD result was at 500 ⁰C annealing temperature. The presence of active Co3O4 phase was supported with the exhibited peaks of four Raman-active phonon modes in the Raman spectra. The quality of as-grown graphene determined from the ratio of 2D-band over G-band intensities is 1.010; an indication of few layers of graphene. Active Co3O4 film is able to produce good quality of graphene comparable with Ni and Cu catalysts. And graphene can be used in many devices, including electronic device, energy storage device, power device, and others