▎ 摘　　要

We synthesized nitrogen-doped graphene quantum dots (N-GQDs) under a high temperature range of 800-1200 degrees C and high pressure of 4.0 GPa through a solid-to-solid process. The graphite N in N-GQDs has a strong negative induction effect on the band gap. Without the interference of surface groups, the direct band gap of these N-GQDs increased with increased nitrogen doping, resulting in tunable photoluminescence (PL) with a high PL efficiency. Based on the recognized PL rules, we synthesised N-GQDs with a higher doping concentration and near ultraviolet light-emittance.