Preparation of large-scale ring carbon nanotube networks and a general growth mechanism for carbon nanotubes

The electrolysis of CO$_2$ in molten carbonate has been introduced as an alternative mechanism to synthesize carbon nanomaterials inexpensively at high yield. Until recently, CO$_2$ was thought to be unreactive, making its removal a challenge. CO$_2$ is the main cause of anthropogenic global warming and its utilization and transformation into a stable, valuable material provides an incentivized pathway to mitigate climate change. This study focuses on controlled electrochemic...

Carbon nanotube (CNT) is expected for much more important and broader applications in the future, because of its amazing electrical and mechanical properties. However, today, the prospect is detained by the fact that the growth of CNTs cannot be well controlled. In particular, controlling the chirality of CNTs seems formidable to any existing growth method. In addition, a systematic method for a designed interconnected network has not been established yet, which is focused pa...

The effect of Fe and Ni catalysts on the synthesis of carbon nanotubes (CNTs) using atmospheric pressure chemical vapor deposition (APCVD) was investigated. Field emission scanning electron microscopy (FESEM) analysis suggests that the samples grow through a tip growth mechanism. High-resolution transmission electron microscopy (HRTEM) measurements show multiwalled carbon nanotubes (MWCNTs) with bamboo structure for Ni catalyst while iron filled straight tubes were obtained w...

The evolution of a continuous Fe(NO3)3 catalyst film was observed by in-situ annealing in a Transmission Electron Microscope (TEM). Such catalysts are routinely used in the catalytic growth of carbon nanotubes. The experiments reveal that crystalline particles form from the gel-like film already around 300C. At usual carbon nanotube growth temperatures of 700C, the particles are single-crystalline with a log-normal size distribution. The observations furthermore show that in ...

An oxygen assisted hydrocarbon chemical vapor deposition (CVD) method is developed to afford large-scale highly reproducible ultra high-yield growth of vertical single-walled carbon nanotubes (SWNT). It is revealed that reactive hydrogen (H)-species, inevitable in hydrocarbon-based growth, are damaging to the formation of sp2-like SWNTs. The addition of oxygen scavenges H-species and provides a powerful control over the C/H ratio to favor SWNT growth. The revelation of the ro...

Persistent currents in rings constructed from carbon nanotubes are investigated theoretically. After studying the contribution of finite temperature or quenched disorder on covalent rings, the complexity due to the bundle packing is addressed. The case of interacting nanotori and self-interacting coiled nanotubes are analyzed in details in relation with experiments.

An investigation concerning the tautness of suspended carbon nanotubes (CNTs), grown using the chemical vapor deposition (CVD) method is presented. The suspended nanotubes were analyzed with both a transmission electron microscope (TEM), and a high resolution scanning electron microscope (HR-SEM). The HR-SEM and TEM investigations revealed that the interactions between CNTs among themselves, and with the surface on which they are grown, is a primary cause for the tautness of ...

The structural and electronic properties of aluminum covered single wall carbon nanotubes (SWNT) are studied from first-principles for a large number of coverage. Aluminum-aluminum interaction that is stronger than aluminum-tube interaction, prevents uniform metal coverage, and hence gives rise to the clustering. However, a stable aluminum ring and aluminum nanotube with well defined patterns can also form around the semiconducting SWNT and lead to metallization. The persiste...

Carbon nanotubes have properties depending on the arrangement of carbon atoms on the tube walls, called chirality. Also it has been tried to grow nanotubes of only one chirality for more than a decade it is still not possible today. A narrowing of the distribution of chiralities, however, which is a first step towards chirality control, has been observed for the growth of nanotubes on catalysts composed of nickel and iron. In this paper, we have calculated carbon-metal bond e...

Carbon nanotubes have been famous since their discovery twenty years ago for their remarkable physical properties, from strength a hundred times higher than steel, to electrical current capacity a 1,000 times higher than copper. But so far they have only been produced at most up to centimeter lengths. Here are presented some proposals to combine the nanotubes in such a way to get arbitrarily long lengths while maintaining their extraordinary physical properties.