Synthesis and characterization of high quantum yield graphene quantum dots via pyrolysis of glutamic acid and aspartic acid

Due to their promising numerous novel applications, such as photovoltaics, organic light-emitting diodes, fuel cells, bioimaging, biosensing, environmental monitoring, and the other interaction with biological systems, graphene quantum dots (GQDs) have steadily become a rising star as a new graphene derivatives member. In this work, we demonstrate a novel, simple, and facile technique for the synthesis of graphene quantum dots. We also investigate the optical and structural properties of the quantum dots using some characterization techniques including high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), UV–Vis absorption, and photoluminescence. The effect of temperature, pyrolysis time, and co-precursor concentration on quantum yield was investigated. The optimum circumstances were found to be a 5% aspartic acid concentration, a 5-min pyrolysis period, and a pyrolysis temperature of 185 °C. At the optimum conditions, the maximum quantum yield of GQDs was found to be 0.89 ± 0.02 and the spherical and crystal lattice structured GQDs were defined with a diameter of 2.05 ± 0.65 nm and the interplanar spacing in the crystalline petal of 0.189 nm. According to the results, the GQDs created are soluble and luminous in aqueous solution and have applications ranging from energy to life sciences.