Optical Absorbance of Graphenic Carbon from Coconut Shells in Different Solvents for Film Preparation

Graphene-based materials have been widely developed in various applications, both in electronics and optoelectronics. It is because of their attractive characteristics, such as flexible structure, large surface area, and excellent thermal, mechanical, and optoelectronic properties. In this research, the optical absorbance of coconut shell-based carbon materials was studied in the exfoliation process and the type of solvent. To determine the effect of optical absorption and particle size of graphene carbon from coconut shells on solvents, we used two types of solvents, namely Deionized (DI) water and a mixture of DMSO and DI (DMSO/DI) with a fraction of 1:10. The exfoliation process is carried out by dissolving graphene powder from coconut shell powder that has been synthesized and heated at 400°C into DI water and DMSO/DI mixture with a concentration of 0.01 g/ml. Ultrasonication is carried out with time variations of 60, 180, 300, and 420 minutes. After ultrasonication for 420 minutes, the absorbance peak was at 241 nm with an average particle size of 134 nm in the solvent DMSO/DI mixture. For the DI solvent, the absorbance peak was at 243 nm with an average particle size of 198 nm. This study showed that the DMSO/DI mixed solvent with a fraction of 1:10 could produce a smaller average particle size than the DI solvent, but the absorbance spectrum is less clear at a wavelength of less than 240 nm compared to the DI water. Furthermore, these two solvents can be used to prepare graphenic carbon films from coconut shells because they are easy to obtain, cheap, and can reduce particle size by ultrasonication.