Carbon, one of the most abundant materials, is very attractive for many applications because it exists in a variety of forms based on dimensions, such as zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and-three dimensional (3D). Carbon nanowall (CNW) is a vertically-oriented 2D form of a graphene-like structure with open boundaries, sharp edges, nonstacking morphology, large interlayer spacing, and a huge surface area. Plasma-enhanced chemical vapor deposition (PECVD) is widely used for the large-scale synthesis and functionalization of carbon nanowalls (CNWs) with different types of plasma activation. Plasma-enhanced techniques open up possibilities to improve the structure and morphology of CNWs by controlling the plasma discharge parameters. Plasma-assisted surface treatment on CNWs improves their stability against structural degradation and surface chemistry with enhanced electrical and chemical properties. These advantages broaden the applications of CNWs in electrochemical energy storage devices, catalysis, and electronic devices and sensing devices to extremely thin black body coatings. However, the controlled growth of CNWs for specific applications remains a challenge. In these aspects, this review discusses the growth of CNWs using different plasma activation, the influence of various plasma-discharge parameters, and plasma-assisted surface treatment techniques for tailoring the properties of CNWs. The challenges and possibilities of CNW-related research are also discussed.
Millimetre-scale patterns formed by plasmas above a surface can drive the formation of and at the same time be directly affected by nano- and micro-scale patterns on that surface.
Vertically oriented graphenes have been grown for more than a decade, but until now the chemical and physical mechanisms underlying their growth have not been fully defined and understood. For this reason, we build a multi-scale, multi-factor model which is thoroughly verified using a large body of experimental data to provide a significant insight into the chemical and physical processes that determine nucleation, growth and structure formation of vertically aligned graphenes in plasma environments. Roles of chemical and physical processes that cannot be directly characterized using presently available experimental techniques, e.g. surface diffusion of adatoms and radicals, are also studied using this model. The leading role of surface diffusion fluxes, rather than direct influx from the gas phase, is confirmed, with ion bombardment being a key factor in ‘switching’ the growth modes by generating surface defects and hence, increasing the surface adsorption energy. Thus, the hydrocarbon radicals generated on a substrate as a result of bombardment are shown to diffuse to the nanoflakes and catalyze the reactions, and serve as the primary source of material to build the nanoflakes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.