Non-synthetic luminescent graphene quantum dots in coconut water for aniline sensing applications

Abstract

We report, for the first time, on non-synthetic luminescent graphene quantum dots (GQDs) which are found to naturally exist in coconut water. Identification of these GQDs was made using HRTEM, XRD, FTIR and XPS measurements. It was found that such naturally occurring GQDs have dual sizes with average size values of 4.5 nm and 6.1 nm and show luminescence in the UV and blue light regions, respectively. The obtained GQDs also show a unique excitation - independent emission and have a luminescence quantum yield of 0.6 %. The dots were utilized interestingly as an efficient luminescence turn-on optical sensor for aniline liquid detection with a low detection limit 0.234 µM.