▎ 摘　　要

L-Tryptophan (Trp) functionalized graphene quantum dots (Trp-GQDs) were prepared via a thermal cracking method, using Trp and citric acid (CA) as raw material. The as-obtained Trp-GQDs show stronger blue photo-luminescence (PL) than simple graphene quantum dots (GQDs). The presence of Trp can obviously improve the luminescent properties of GQDs. The possible mechanism was investigated for the formation and luminescence properties of the Trp-GQDs. Furthermore, the Trp-GQDs exhibit a good liner relationship between fluorescence response and pH variation within the pH range of 4-12. More importantly, Trp-GQDs still perform well in sensitivity to pH values in real water samples. The results indicate that the probe shows great potential in pH detection.