Hydrothermal route to graphene quantum dots: Effects of precursor and temperature

This work adopts a hydrothermal approach to produce graphene quantum dots (GQDs) from different precursors including carbon nanotube (CND, graphene oxide (GO), and carbon black (Super P, SP). The report also explores the effects of hydrothermal temperature on the particle size and photoluminescence (FL) of GQDs. The experiments show that GQDs obtained from CNTs not only have the lowest particle size (similar to 1.56 nm) but also offer the highest PL intensity, as compared to the GQDs prepared from GO and SP. The study on temperature effect reveals that GQD size decreases as hydrothermal temperature increases, which can be attributed to the formation of OH radicals that cleaves graphite at higher temperature. The PL study confirms that the GQDs show a blue shift behavior as the particle size decreases. The as-prepared GQDs produce yellow and blue photoluminescence. Therefore, this study provides an efficient method to tune the PL characteristics of GQDs, easing the development of optoelectronic materials for energy and biological applications.