Carbon nanotubes coated with diamond nanocrystals and silicon carbide by hot-filament chemical vapor deposition below 200 °C substrate temperature

Gough

et al. 2019

Carbon

114

Nanosized and crystalline sp 3-bonded carbon materials were prepared over large surface areas up to ~33x51 m 2 from the exposure of few-layer graphene (FLG) to H radicals produced by the hotfilament process at low temperature (below 325 C) and pressure (50 Torr). Hybrid materials were also obtained from the partial conversion of FLG. sp 3-C related peaks from diamond and/or lonsdaleite and/or hybrids of both were detected in UV and visible Raman spectra. C-H bonding was directly detected by Fourier Transform Infrared (FTIR) microscopy over an area of ~150 m 2 and one single component attributed to sp 3-C-H mode was detected in the C-H stretching band showing that carbon is bonded to one single hydrogen and strongly suggesting that the sp 3-C materials obtained are ultrathin films with basal planes hydrogenated. The experimental results are compared to computational predictions and comprehensively discussed. Those materials constitute new synthetic carbon nanoforms after fullerenes, nanodiamonds, carbon nanotubes and graphene. This opens the door to new research in multiple areas for the development of new potential applications and may have wide scientific impact, including for the understanding of extraterrestrial diamond-related structures and polytype formation mechanism(s).

Section: Hydrogenation Processmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Low temperature, pressureless sp2 to sp3 transformation of ultrathin, crystalline carbon films

Gough

et al. 2019

Carbon

114

“…A commercial hot filament reactor was used for the hydrogenation process [21]. The specific experimental details related to the synthesis of diamane and diamanoid/graphene hybrids were previously disclosed [2,17,18].…”

Section: Hydrogenation Processmentioning

confidence: 99%

“…The hotfilament process was successfully used to grow crystalline nanodiamonds at low substrate temperature, below 300 • C, on temperature-sensitive substrates such as kapton ® VN [49][50][51]. Notably, it was then used to conformally coat carbon nanotube bundles with diamond and SiC nanocrystals from solid carbon and silicon sources exposed to H at ~190 • C, before the nanotubes could be etched away [21,52]. Figure 1a displays a typical UV Raman spectrum of such a material (see the corresponding scanning electron microscopy image in Figure 1b), showing a sharp diamond peak at about 1325 cm −1 from diamond nanocrystals at the surface of nanotube bundles.…”

Section: Hot-filament Process To Efficiently Hydrogenate Graphene Materialsmentioning

confidence: 99%

Progress on Diamane and Diamanoid Thin Film Pressureless Synthesis

Puech

et al. 2021

Nanometer-thick and crystalline sp3-bonded carbon sheets are promising new wide band-gap semiconducting materials for electronics, photonics, and medical devices. Diamane was prepared from the exposure of bi-layer graphene to hydrogen radicals produced by the hot-filament process at low pressure and temperature. A sharp sp3-bonded carbon stretching mode was observed in ultraviolet Raman spectra at around 1344–1367 cm−1 while no sp2-bonded carbon peak was simultaneously detected. By replacing bi-layer graphene with few-layer graphene, diamanoid/graphene hybrids were formed from the partial conversion of few-layer graphene, due to the prevalent Bernal stacking sequence. Raman spectroscopy, electron diffraction, and Density Functional Theory calculations show that partial conversion generates twisted bi-layer graphene located at the interface between the upper diamanoid domain and the non-converted graphenic domain underneath. Carbon-hydrogen bonding in the basal plane of hydrogenated few-layer graphene, where carbon is bonded to a single hydrogen over an area of 150 μm2, was directly evidenced by Fourier transform infrared microscopy and the actual full hydrogenation of diamane was supported by first-principle calculations. Those results open the door to large-scale production of diamane, diamanoids, and diamanoid/graphene hybrids.

“…1b. A commercial hot filament reactor (BWI 1000 model from Blue Wave Semiconductors) was used for the hydrogenation process [9]. The specific experimental details related to the synthesis of diamanoïds were previously disclosed [2].…”

mentioning

confidence: 99%

Raman evidence for the successful synthesis of diamane

Cruz

et al. 2020

Carbon

Diamane was prepared from the exposure of bi-layer graphene to H radicals produced by the hot-filament process. A sharp sp 3 -bonded carbon stretching mode was observed by UV Raman spectroscopy while no sp 2 -bonded carbon peak was simultaneously detected. This is the first time that Raman spectra of genuine diamane are reported, which, meanwhile, are the very first evidence for the successful synthesis of genuine diamane. First principle calculations support possible full hydrogenation and confirm the hydrogenated AB configuration to be the most stable one. We believe those results constitute a milestone in the path towards the synthesis of high-quality diamane and open the door to large-scale production. Genuine diamane consists of two crystalline sp 3 −bonded carbon layers for which half of the carbon atoms are hydrogenated while the other half bond the two layers to each other [1,2]. The material stability was first predicted by Chernozatonskii et al in 2009 [1]. The increasing interest in this new 2D wide bang-gap semiconducting material comes, in particular, from its potential use in electronics [3]. Recently, the synthesis of stable 2D nanometer-thick and crystalline sp 3 -bonded carbon, was unambiguously shown for the first time [2,4]. This breakthrough was achieved from