Plasma Produced and Processed Multimaterials Based on Vertically Aligned Graphene Walls and Their Applications
Résumé
The interest in new carbonaceous materials with large effective surfaces which are in addition highly conductive and stable is growing due to the downsizing of electrical devices and the demand for new low-cost materials. Carbonaceous materials show in in particular a great potential for applications in electrochemical devices, energy storage devices or biosensors. On the other hand, there is also an emerging need for new production methods which allow an environmentally friendly, low cost and scalable synthesis of these materials.
Although there exists no miracle or unicorn method meeting all these demands, one special place in this race for new technologies are novel low temperature/cold plasma processes, which guarantee the synthesis and treatments of materials in dry processes which can go down to almost ambient temperatures.
In this work, we present plasma synthesised and functionalized carbon-based nanomaterials, alone or enrobed in polymers, and their analysis. Moreover, the underlying production process will be analysed both experimentally and by means of simulations.
The carbon nanomaterials are all produced by low temperature plasma procedures, and examples are given for different processes including catalyst-free or catalyst driven processes. All these processes result often in conductive nanostructures, like free-standing graphene, vertically aligned graphene nanosheets, thin films or nanoparticles. These materials are either pure carbons, hydrocarbons or nitrogen-containing carbons. In this presentation we will concentrate on nitrogen free and nitrogen containing vertically aligned graphene. Nitrogen introduction is obtained here either by the growth of the carbonaceous materials in a nitrogen-containing atmosphere or by means of plasma post-treatments. These post-treatment processes can lead to both doped and functionalized materials. A popular technique to simulate plasma-surface interactions is molecular dynamics (MD). MD simulations can provide insight into fundamental mechanisms like the formation of different kinds of bonds.
The plasma produced graphene stuctures can be, (depending on the applications), additionally decorated with conductive nanoparticles or thin films. One example concerns the conformal coating or enrobing with plasma polymers, as for example plasmapolyaniline. The interplay between doping, functionalization together with enrobing/decoration is advantageous and results in different surface characteristics of interest which can be useful e.g. for the synthesis of storage devices.