Vertically free-standing few-Layer graphene-based carbon nanosheets, also known as carbon nanowall, vertically oriented graphene nanosheets, are complicated thin film materials having a hierarchical structure produced on a substrate. Vertical graphene thin films have recently gained a lot of attention as an outstanding platform material due to its unique features. Alfa Chemistry offers custom graphene synthesis services to produce high quality vertical graphene thin films.
Plasma VG Thin Films
Different nanostructures are formed when graphene film synthesis occurs near a high-energy plasma, and Alfa Chemistry uses a strong electric field in the plasma sheath to drive the growth of graphene material in a vertical direction perpendicular to the substrate, resulting in a typical 3D graphene structure called vertical graphene (VG). Methane (CH4) and acetylene (AC) are two of the most widely used precursor gases (C2H2). We can grow VG on a variety of substrates, including glass, quartz, metals, semiconductors, and insulators. Please contact us if you have any particular requirements.
Fig 1. Growth mechanism of VG. (a) Low- and (b) high-magnification TEM images showing VG growth from the underlying buffer layer. (c) TEM image showing the formation of VG from carbon onions. (d) High-resulution TEM image showing that mismatching regions in carbon onions can act as nucleation sites for VG growth. (e)-(f) Schematic illustration of VG growth on buffer layers. (Zhao J, et al. 2014)
Method Advantages:
- The synthesis does not require a catalyst, which eliminates the need to remove metal catalysts after synthesis, making it a highly compatible device integration approach.
- External heating is not required for growth in or inside the plasma area because the high-energy plasma supplies adequate heat and energy, reducing system complexity.
Controlled Growth
Gas composition, hydrogen, carrier gas, plasma source, and external parameters can all be used to influence growth. It has been shown that increases the growth rate by altering the substrate temperature and the ratio of carbon precursor gas to hydrogen gas mixture.
The individual sheet size of the VG rises as the carbon precursor gas content increases until the saturation point is reached. Smaller individual sheet sizes and denser vertical graphene films are generated as the carbon precursor to hydrogen ratio approaches 1:1. When the carbon precursor content exceeds the hydrogen content, atomically thick graphene films form.
VG growth is influenced by a variety of substrates, including dielectric and metallic surfaces. We found that Cu is more effective in generating higher density VGs compared to dielectric substrates because Cu aids in the catalytic decomposition of hydrocarbon precursors and increases hydrocarbon radicals, resulting in denser vertical graphene nanosheets.
The shape and aspect ratio of VG is also affected by the synthesis time. The height and density of VG grow as the synthesis time increases.
Modification
VG not only has many fundamental graphene properties, such as high electrical conductivity, thermal conductivity, chemical stability, large specific surface area, and chemically active edges and defects, but it also has a high density of reactive edges and a unique 3D and linked porosity.
VGs have a lot of sharp, exposed, vertically pointed edges that can be used to adsorb functional materials and dopants like enzymes, antibodies, Au, Pt, and other things. Alfa Chemistry can also supply customers with VG material modification services. We use a novel method to change the characteristics of nanostructures without considerably increasing the weight or affecting the VG sheet's shape.
Reference
- Zhao J, et al. (2014). "A Growth Mechanism for Free-Standing Vertical Graphene" Nano Lett. 14: 3064.
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