Solubility of Modified Catalyst-free Carbon Nanowall with Organic Solvents

Abstract In this article, chemical-vapor-deposition-(CVD)-based pristine carbon nanowall (PCNW) was modified in oxygen plasma and a hydrothermal reduction system into oxidized carbon nanowall (OCNW) and reduced oxidized carbon nanowall (rOCNW). The solubility behavior of the functional groups formed on the PCNW, OCNW, and rOCNW surfaces in ketone- and alcohol-type organic solvents was demonstrated and investigated. When the surfaces of the samples reacted with acetone and methanol were magnified, OCNW showed very high solubility. This indicated that most of the functional groups existed on the surface of OCNW, and that these functional groups reacted the most with the organic solvents, forming H bonding. The dispersion analysis confirmed that the solubility was induced by the activity in the functional groups bonded with the molecules of acetone and methanol. The X-ray photoelectron spectra showed clear changes in hydroxyl and carbonyl, suggesting that hydroxyl and carbonyl are key groups. The ID/IG ratio in the Raman spectra after the reaction with the organic solvents slightly increased. Local dissociation is expected after absorption by the organic solvents into the weak points where the carbon branches were removed by the oxygen plasma. As in the experiment, the prepared CNW reacted with the organic solvents, which showed different results from the carbon-based materials.