Synthesis and upconversion luminescence of N-doped graphene quantum dots

Abstract
A hydrothermal approach was developed for the synthesis of N-doped graphenequantum dots (N-GQDs) by cutting N-doped graphene. The N-GQDs obtained have a N/C atomic ratio of ca. 5.6% and diameter of 1–7 nm. The photoluminescence(PL)properties of the N-GQDs were investigated. It was found that the N-GQDs possess bright blue PL and excellent upconversion PLproperties.