S. Ike, R. Vander Wal
Penn State University,
United States
Keywords: graphene oxide (GO), Novolac, synthetic graphite, templating, graphitization
Summary:
Increasing graphite demand for energy storage applications creates an urgent need to make graphite using precursors and processes that are affordable and friendly to the environment. Non-graphitizing precursors such as polymers, biomass, etc. are known for their abundance, low cost, sustainability, and high carbon content; therefore, graphitizing them will be a welcome achievement. In this work, a process of converting a non-graphitizing precursor, a phenolic resin novolac (N) into a graphitic carbon is presented. This was achieved by the addition of five additives categorized as graphene oxide (GO) and its derivatives, reduced graphene oxide (RGO) and graphene nanoplatelets (GPL) with varied oxygen group concentrations. The hypothesis is that the additives act as templates that promote matrix aromatic alignment to their basal planes during carbonization (physical templating) in addition to forming radical sites that bond to the decomposing matrix (chemical templating). Results showed that the addition of RGO additives of equivalent oxygen content, 15.4 at.(%) and 14.4 at.(%), to the novolac matrix (RGO-N) gave parallel results and show the best graphitic quality after high temperature treatment (HTT) as measured by XRD. Selected area electron diffraction showed the formation of sheet stacks and well-defined lattice fringes in the graphitized RGO-N materials. In contrast, XRD results show the addition GO additive of twice or more oxygen content ≥ 30.8 at.(%) to the novolac matrix (GO-N) led to poor graphitic quality after HTT. This suggests that there is a threshold of oxygen content in GO additives needed to induce graphitization of the novolac matrix. This work is important because of the current need for graphitic materials, especially for energy storage applications. Additionally, the templating technique could be a more environmental and cost-effective method to turn non-graphitizing precursors into graphitizable ones.