3-D porous hierarachical nanostructured materials by low temperature green plasma chemistry and plasma-surface interactions for applications in energy storage

Abstract

In this paper we present the review of various research works that our group has done to develop a simple and environmentally-friendly approach for (i) green plasma chemistry based synthesis of free standing 3-D carbon nanostructures, particularly graphene nanomesh and vertical graphene, using low flash point sustainable essential oils that vaporize easily and can be easily admitted into plasma chamber just like any gaseous precursor, and (ii) nano-structurization as well functionalization of prefabricated commercial material surfaces by low temperature plasma-surface interactions to prepare 3-D porous hierarchical materials. In first set of experiments, the 3-D vertical graphene (synthesized using indigenously designed RF plasma enhanced chemical vapor deposition/processing facility) were then anchored by suitable energy storage active material such as nanosheets of MnO2 and MoS2 to prepare MnO2@3DVG and MoS2@3DVG electrode for supercapacitor and lithiumion battery assembly. Dense packed vertical graphene based 3D nanostructures were found to exhibit enhanced performance for energy storage applications due to their unique hierarchical structure and reactive edges. In second set of experiments, plasma-surface interaction was used as the tool to process the commercial carbon fibers and nickel foam to create nitrogen functionalized 3-D porous hierarchical nanostructured networks. Few fold improvement in Li-ion storage and excellent overall electrochemical performance was exhibited by nitrogen functionalized 3-D porous nanoarchitectured surface making this method an attractive pathways for development of next generation energy storage devices.