Characteristics of CVD Grown Multi-Layer Graphene under Different Types of Precursors and Their Respective Flow Rate

Abstract

In this work, atmospheric pressure chemical vapor deposition (CVD) method was used to synthesize multi-layer graphene (MLG) on copper substrate. The MLG samples were grown under different type of liquid precursors, i.e. methanol, ethanol, and heptane, with different flow rate of hydrogen (H 2 ) (combination of both denoted as precursor flow rate). The transferred graphene film onto glass substrate have good coverage area as evident from AFM measurements, however, morphological differences were less notable among precursor types. Post-processing of Raman results revealed an inverse relation of the graphene crystallite size (L a ) and average distance between point defects (L D ) toward precursor flow rate and ascending order of hydrocarbon compound. Furthermore, analysis on the G band indicated that graphene synthesized from lower order hydrocarbon compounds possessed better crystalline quality since the peak position was comparable to that of a relaxed state, i.e. at 1580 cm −1 . Transmittance data of the samples were used to deduce the number of graphene layers. Overall, the synthesized graphene consisted of 3∼19 layers. A direct relation between number of graphene layers and precursor flow rate was observed from there.

Interfacial Engineering of Graphene Nanosheets at MgO Particles for Thermal Conductivity Enhancement of Polymer Composites

“…It is clearly shown that the microsized MgCO 3 granules were orderly assembled by wafer-like nanosheets, unlike the general cubic structure with epitaxial growth along one crystalline direction [19]. The size of MgCO 3 granules was well controlled in the range of 5–10 μm, providing desirable platforms for the growth of graphene with microsized planar sheets [20]. Upon high-temperature decomposition, the MgCO 3 precursors were transformed to MgO templates with slightly decreased size, accompanied by the degradation of sheet thickness (Figure 1c,d).…”

“…It was accompanied by the observation of D band located at 1330 cm −1 , pointing to the existence of structural defects of graphene. The 2D band (excited by a double-resonant Raman process) located at 2677 cm −1 was attributed to the double resonance effects of the D band, indicating the existence of few-layer graphene presented in G@MgO [20,29]. The presence of ordered and graphitized carbons attached to the MgO particles, instead of normal graphene oxide, probably contribute to the promotion of interfacial adhesion and TC [30].…”