In‐Liquid Plasma Synthesis of Nanographene with a Mixture of Methanol and 1‐Butanol

Abstract Nanometer‐size graphene sheets (nanographene) were synthesized by the in‐liquid plasma method employing a mixture of alcohols. Pure methanol in‐liquid plasma was found to not synthesize any nanographene. Pure ethanol synthesized nanographene with high crystallinity. Highly crystalline nanographene with a narrow full width‐half maximum of the Raman scattering G‐band (FWHM_G) was obtained by mixing 1‐butanol with methanol. This is due to the formation of carbon ring structures being inhibited by the addition of methanol. The ratio of added methanol determined the nanographene crystallinity and yield under a trade‐off relationship, allowing the crystallinity and nanographene yield to be controlled by controlling the ratio. Gas chromatography‐mass spectrometric analysis of by‐products in the liquids’ supernatant showed that the crystallinity of the synthesized nanographene correlated with the ratio of carbon over oxygen of the alcohol precursors (C/O), i. e., the amount of hydroxyl groups in the liquids, and hence controlling the C/O ratio can be used to control the graphene crystallinity in the in‐liquid plasma synthesis.