AVS 66th International Symposium & Exhibition
    Plasma Science and Technology Division Wednesday Sessions
       Session PS+EM-WeM

Paper PS+EM-WeM6
Comparison of Pulsed and Continuous Wave Argon Plasmas for the Synthesis of Vertical Graphene Nanosheets

Wednesday, October 23, 2019, 9:40 am, Room B131

Session: Plasma Processing of Materials for Energy
Presenter: Zoe Mann, Colorado State University
Authors: Z. Mann, Colorado State University
E.R. Fisher, Colorado State University
Correspondent: Click to Email
Vertical graphene nanosheets (VGNs) have unique structural and electronic properties that make them applicable in fields such as energy storage, electronics, and sensing. VGNs are often grown using high-power, high-temperature processes and hazardous or unsustainable precursors such as methane. For this reason, we sought to develop a simple, efficient, and more environmentally-friendly way to synthesize VGNs. In this work, VGNs are synthesized from butter or coconut oil (sustainable, non-toxic precursors) spread on a Ni foam or Cu substrate and then treated with a high peak power pulsed plasma process. The materials formed through this process are compared to those produced with a continuous wave treatment of equivalent power and a low peak power pulsed plasma treatment, as well as to the untreated material. We used a range of characterization techniques to assess the materials, including scanning election microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and cyclic voltammetry, providing data on the morphology, surface chemistry, bulk characteristics, and electrochemical performance, respectively. SEM imaging shows that VGNs grown by the high power pulsed PECVD technique have high surface area and abundant ultra-thin edges. XPS analysis of untreated butter and the low-power pulsed plasma treated samples reveals binding environments consistent with the chemical composition of triglycerides (the primary chemical component in butter/oil), whereas the XPS and Raman spectra of VGNs indicate the presence of sp2-hybridized carbon. Notably, cyclic voltammograms of VGNs formed on Ni foam are characteristic of a capacitor, and these materials do not exhibit the deleterious side reactions found with VGNs formed on the Cu substrate. To better understand the underlying chemistry occurring during plasma treatment, optical emission spectroscopy data were collected, revealing key information on species important for VGN synthesis, such as atomic and molecular carbon.