Advancements in Plasma-Enhanced Chemical Vapor Deposition for Producing Vertical Graphene Nanowalls

Abstract

In recent years, vertical graphene nanowalls (VGNWs) have gained significant attention due to their exceptional properties, including their high specific surface area, excellent electrical conductivity, scalability, and compatibility with transition metal compounds. These attributes position VGNWs as a compelling choice for various applications, such as energy storage, catalysis, and sensing, driving interest in their integration into next-generation commercial graphene-based devices. Among the diverse graphene synthesis methods, plasma-enhanced chemical vapor deposition (PECVD) stands out for its ability to create large-scale graphene films and VGNWs on diverse substrates. However, despite progress in optimizing the growth conditions to achieve micrometer-sized graphene nanowalls, a comprehensive understanding of the underlying physicochemical mechanisms that govern nanostructure formation remains elusive. Specifically, a deeper exploration of nanometric-level phenomena like nucleation, carbon precursor adsorption, and adatom surface diffusion is crucial for gaining precise control over the growth process. Hydrogen’s dual role as a co-catalyst and etchant in VGNW growth requires further investigation. This review aims to fill the knowledge gaps by investigating VGNW nucleation and growth using PECVD, with a focus on the impact of the temperature on the growth ratio and nucleation density across a broad temperature range. By providing insights into the PECVD process, this review aims to optimize the growth conditions for tailoring VGNW properties, facilitating applications in the fields of energy storage, catalysis, and sensing.

Vertical graphene nanowalls supported hybrid W2C/WOx composite material as an efficient non-noble metal electrocatalyst for hydrogen evolution

“…To overcome the above challenges, here, we proceed with the preparation of hybrid compounds of W 2 C/WO x (where x: 2 or 3) deposited on VGNWs. VGNWs show high specific surface area, comparable to this of CNTs, excellent electrical conductivity, scalability, and compatibility with transition metal compounds, which make them an ideal support system for the deposition of WC [ 20 ]. VGNWs are deposited through chemical vapor deposition, using CH 4 as a precursor gas, and elemental W is deposited on them via magnetron sputtering in Ar atmosphere.…”

Graphene nanowalls grown on copper mesh

“…For the most part, graphene films are produced with the basal plane parallel to a substrate. However, in recent years, the study of nanoscaled graphitic carbon sheets with basal planes oriented vertically to a surface, also called graphene nanowalls (GNW s ) or vertical graphene (VG), has drawn increased attention from the community [12][13][14][15][16][17]. The films of GNW s commonly aggregate large numbers of intertwined sheets, where each nanowall is composed of one to a few tens of wavy graphene layers that extend laterally for hundreds of micrometers [15,18,19].…”

“…However, in recent years, the study of nanoscaled graphitic carbon sheets with basal planes oriented vertically to a surface, also called graphene nanowalls (GNW s ) or vertical graphene (VG), has drawn increased attention from the community [12][13][14][15][16][17]. The films of GNW s commonly aggregate large numbers of intertwined sheets, where each nanowall is composed of one to a few tens of wavy graphene layers that extend laterally for hundreds of micrometers [15,18,19]. Given their orientation, both the bottom and top surfaces of the vertically-aligned graphene stack are exposed which, added to its cross-sectional surface (i.e.…”

Processing and Functionalization of Vertical Graphene Nanowalls by Laser Irradiation

“…Conclusively, with the control of the laser fluence and number of applied pulses, the crystal quality of the VGNWs can be modified on demand. This feature can serve for the tuning of the physicochemical properties of the VGNWs and has important implications on their use on energy storage, catalysis, and sensing applications …”

“…This feature can serve for the tuning of the physicochemical properties of the VGNWs and has important implications on their use on energy storage, catalysis, and sensing applications. 31 …”