The influence of concentration of carbon sheets in hydrothermal synthesis of graphene quantum dots

Abstract

Graphene quantum dots (GQDs) as a derivative of graphene have attracted tremendous attention due to their great potential in a variety of advanced applications including optoelectronics, spintronics, energy conversion, sensing and so on. A green route to synthesize graphene quantum dots combining both bottom-up and top-down processes has recently been developed in our group. It involves bottom-up synthesis of carbon sheets from citric acid molecules and hydrothermally cutting the carbon sheets into graphene quantum dots. In this paper, the influence of concentration of carbon sheets on the hydrothermal cutting process was demonstrated. It is found that the concentration of carbon sheets significantly affects the hydrothermal cutting process. In order to obtain efficient cutting, an optimum concentration is necessary. Too high a concentration results in serious agglomeration of resulting graphene quantum dots, which could be indicated by the degradation of photoluminescence of the hydrothermally treated products with increase of carbon sheets concentration. On the contrary, too low a concentration means a low yield of GQDs. The study seeks to establish the relationship between the carbon sheets concentration and the efficiency of the hydrothermal cutting process.