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Nonmetal Si[O.sub.x] nanoparticles (NPs) have tailored few-layer graphenes (FLGs) into graphene nanoribbons (GNRs) and regular pieces with smooth-edges. The studies have shown the possibility for atomically precise graphene device fabrication without metal contamination and have shown the potential catalytic activity of nonmetal NPs for the hydrogenation of carbon materials.

A simple and efficient method is described for realizing the growth of single walled carbon nanotubes (SWNTs) with a metal-catalyst-free chemical vapor deposition (CVD) process. The successful growth of SWNTs using nonmetal catalyst has helped in understanding the growth mechanism of SWNTs, which has facilitated the controllable synthesis and applications of carbon nanotubes.

Recently, chemical synthesis of a range of large nanographene molecules with various shapes and sizes opened a new path to utilize them in various applications and devices. However, due to their extended aromatic cores and high molecular weight, film formation of large nanographene molecules, bearing more than 90 sp² carbon atoms in aromatic cores, is very challenging, which has prevented their applications such as in thin-film transistors. Here, we developed an effective approach to prepare films of such large nanographene molecules using a vapor-phase transport (VPT) technique based on molecule sublimation. The VPT of these molecules was made possible by combining the molecules and the target substrate in a small confinement of vacuum-sealed glass tube, so that a small amount of sublimation can be utilized to create films. Surprisingly, such heavy and large molecules can be deposited on any substrate by this method to create films of assembled large nanographene molecules while maintaining their aromatic cores intact, which was confirmed using mass spectrometry measurements. Moreover, field-effect transistors based on these films are depleted and show significantly improved current on/off ratio compared to previous large nanographene-based transistors fabricated using liquid-phase-based process. Our work shows that VPT deposition can be a viable technique to prepare films based on large nanographene molecules and potentially other high molecular weight compounds, which may find exciting applications in electronics and optoelectronics. [ABSTRACT FROM AUTHOR]

To understand in-depth the nature of the catalyst and the growth mechanism of single-walled carbon nanotubes (SWCNTs) on a newly developed silica catalyst, we performed this combined experimental and theoretical study. In situ transmission electron microscopy (TEM) observations revealed that the active catalyst for the SWCNT growth is solid and amorphous SiOx, nanoparticles (NPs), suggesting a vapor-solid-solid growth mechanism. From in situ TEM and chemical vapor deposition growth experiments, we found that oxygen plays a crucial role in SWCNT growth in addition to the well-known catalyst size effect. Density functional theory calculations showed that oxygen atoms can enhance the capture of -CHx and consequently facilitate the growth of SWCNTs on oxygen-containing SiOx, NPs. [ABSTRACT FROM AUTHOR]

The article presents a study on the crystallographic orientation of graphene nanoribbons (GNRs) through the catalytic tailoring of nonmetal SiOx nanoparticles (NPs) compared to metal NPs. It mentions the ideal way of opening gaps in the electronic structure of graphene in GNRs as metal NP's intrinsic properties remained. Moreover, the tailored graphene is realized by nonmetal movement in which tailored trenches exhibits high crystallographic orientation compared to metal NPs.