Surface Hydride Composition of Plasma-Synthesized Si Nanoparticles

We have determined the surface hydride composition of amorphous and crystalline Si nanoparticles (NPs) (3-5 nm) synthesized in a low-temperature SiH(4)/Ar plasma using in situ attenuated total reflection Fourier-transform infrared spectroscopy and H(2) thermal effusion measurements. With increasing power to the plasma source, the particles transition from amorphous to crystalline with a corresponding increase in the fraction of SiH species on the surface. The surface hydride composition indicates that Si NPs synthesized at higher plasma powers crystallin in the gas-phase due to a greater degree of plasma-induced heating, which enhances the desorption rates for SiH(2) and SiH(3). Furthermore, these Si NPs do not contain any detectable H in the bulk

Carbon monoxide-induced reduction and healing of graphene oxide

Graphene oxide holds promise as a carbon-based nanomaterial that can be produced inexpensively in large quantities. However, its structural and electrical properties remain far from those of the graphene sheets obtained by mechanical exfoliation or by chemical vapor deposition unless efficient reduction methods that preserve the integrity of the parent carbon-network structure are found. Here, the authors use molecular dynamics and density functional theory calculations to show that the oxygen from the main functional groups present on graphene oxide sheets is removed by the reducing action of carbon monoxide; the energy barriers for reduction by CO are very small and easily overcome at low temperatures. Infrared and Raman spectroscopy experiments confirm the reduction in CO atmosphere and also reveal a strong tendency for CO to heal vacancies in the carbon network. Our results show that reduced graphene oxide with superior properties can be obtained through reduction in CO atmosphere