Fluorobenzene and Water-Promoted Rapid Growth of Vertical Graphene Arrays by Electric-Field-Assisted PECVD

Vertical graphene (VG) arrays show exposed sharp edges, ultra-low electrical resistance, large surface-to-volume ratio, and low light reflectivity, thus having great potential in emerging applications, including field emission, sensing, energy storage devices, and stray light shields. Although plasma enhanced chemical vapor deposition (PECVD) is regarded as an effective approach for the synthesis of VG, it is still challenging to increase the growth rate and height of VG arrays simultaneously. Herein, a fluorobenzene and water-assisted method to rapidly grow VG arrays in an electric field-assisted PECVD system is developed. Fluorobenzene-based carbon sources are used to produce highly electronegative fluorine radicals to accelerate the decomposition of methanol and promote the growth of VG. Water is applied to produce hydroxyl radicals in order to etch amorphous carbon and accelerate the VG growth. The fastest growth rate can be up to 15.9 µm h^-1 . Finally, VG arrays with a height of 144 µm are successfully synthesized at an average rate of 14.4 µm h^-1 . As a kind of super black material, these VG arrays exhibit an ultra-low reflectance of 0.25%, showing great prospect in stray light shielding.

Nitrogen, Oxygen-Codoped Vertical Graphene Arrays Coated 3D Flexible Carbon Nanofibers with High Silicon Content as an Ultrastable Anode for Superior Lithium Storage

Free-standing and foldable electrodes with high energy density and long lifespan have recently elicited attention on the development of lithium-ion batteries (LIBs) for flexible electronic devices. However, both low energy density and slow kinetics in cycling impede their practical applications. In this work, a free-standing and binder-free N, O-codoped 3D vertical graphene carbon nanofibers electrode with ultra-high silicon content (VGAs@Si@CNFs) is developed via electrospinning, subsequent thermal treatment, and chemical vapor deposition processes. The as-prepared VGAs@Si@CNFs electrode exhibits excellent conductivity and flexibility because of the high graphitized carbon nanofiber network and abundant vertical graphene arrays. Such 3D all-carbon architecture can be fabulous for providing a conductive and mechanically robust network, further improving the kinetics and restraining the volume expansion of Si NPs, especially with an ultra-high Si content (>90 wt%). As a result, the VGAs@Si@CNFs composite demonstrates a superior specific capacity (3619.5 mAh g^-1 at 0.05 A g^-1 ), ultralong lifespan, and outstanding rate capability (1093.1 mAh g^-1 after 1500 cycles at 8 A g^-1 ) as a free-standing anode for LIBs. It is believed that this work offers an exciting method for developing free-standing and high-energy-density electrodes for other energy storage devices.