Carbon nanotubes, nanorings, and nanospheres: Synthesis and fabrication via chemical vapor deposition—a review

Abstract

Research work published since 2010 on the synthesis of carbon nanotubes (CNTs), carbon nanorings (CNRs), and carbon nanospheres (CNSs) using the chemical vapor deposition (CVD) process is reviewed. The effect of CVD process parameters on carbon nanomaterials morphology, such as diameter, yield, and quality was reviewed. The mechanism of CVD formation and growth of carbon nanomaterials was reviewed in detail. The catalyst materials used to synthesize these carbon allotropies were discussed in detail. The formation mechanism of carbon nanomaterials indicates that the variables of the CVD process parameters that appear to control growth are not directly manipulated in the CVD process. Rather, it is determined by complex interactions between variables. The impact of CNTs, CNRs, and CNSs was discussed using the schematic representation. The researchers who published the articles in the CNTs, CNRs, and CNSs for the past decade were discussed. From the intensive literature review, it was found that as compared to CNTs there is not much research was undertaken in synthesizing spheres and rings. But spheres and rings are capable of performing better than CNTs structure in energy storage, and sensors.

Fabrication of tunable band gap carbon based zinc nanocomposites for enhanced capacitive behaviour

“…Carbon nanospheres are formed as a result of the pairing of pentagonal and heptagonal carbon rings which form circular concentric graphite layers and are called carbon nanospheres. They can be synthesized by a variety of methods including chemical deposition method (CVD), hydrothermal method and by usage of hydrocarbons and biomass [11][12][13][14][15][16][17][18]. They can be used in a variety of applications viz.…”

Direct Growth of Binder-Free CNTs on a Nickel Foam Substrate for Highly Efficient Symmetric Supercapacitors

“…In addition, methane, ethylene, acetylene, xylene, benzene, and carbon monoxide are commonly used CNT precursors. According to previous knowledge from the literature, acetylene is a well-known precursor gas to tailor the molecular structure and morphology of CNTs grown in low temperate (600–900 °C) ranges. , Three types of CNT purification procedures, including chemical, physical, and a combination of both, have been used to purify CNTs. The chemical purification process was useful due to its selectivity, cost-effectiveness, easy availability, and fast kinetics of oxidation of carbonaceous impurities from pristine CNTs, whereas the physical purification process is quite complex, time-consuming, and less effective in removing carbon impurities.…”

Pulsed Laser Deposition of Carbon-Based Materials: A Focused Review of Methods and Results

“…Therefore, many experimental techniques have been and are still being developed to produce C-based materials with controlled chemistry and morphology, aiming both to implement scalable methods for industry applications and to gain fundamental insight into currently less understood aspects of carbon chemistry. These include chemical methods, such as chemical synthesis [5][6][7], Chemical Vapor Deposition (CVD) [8][9][10][11][12][13], pyrolysis [14][15][16] and Atomic Layer Deposition (ALD) [17][18][19][20], and physical deposition methods, such as sputtering [17][18][19][20] and Molecular Beam Epitaxy (MBE) [21][22][23].…”