交 联 剂 改 善 羧 基 化 石 墨 烯 量 子 点 荧 光 性 能

1-（3-dimethylaminopropyl）-3-ethyl carbodiimide hydrochloride（EDC）as a water-soluble carbodiimide crosslinking agent，it is widely used in nanomaterial research. The utilization of EDC is as a key component in the design and functionalization of nanomaterials for diverse applications. This study focused on carboxyl-functionalized graphene quantum dots（C-GQDs）and investigated the impact of EDC on its optical properties which has received limited attention previously. This method can effectively enhance the fluorescence intensity of C-GQDs. In experiments，C-GQDs and EDC were reacted to form C-GQDs/EDC complexes via a one-step aqueous method. Experimental results demonstrate that after reaction with EDC，the fluorescence of C-GQDs/EDC is significant enhanced by approximately 23 times. Additionally，the impact of factors such as solution concentration，light irradiation，and reaction time on fluorescence were also validated. Fluorescence spectroscopy analysis indicates that the luminescence of C-GQDs is the result of a multi-process interplay involving intrinsic，surface，and defect-state energy level transitions. Abundance of defect energy levels in original C-GQDs contributed to the weakened luminescent performance. The mechanistic analysis suggests that the activation reaction occurring between EDC and carboxyl groups plays a role in surface defect passivation，thereby improving the surface-state exciton recombination efficiency of C-GQDs. This effectively addresses the low luminescence issue of C-GQDs. This work extends the potential applications of GQDs and provides a reference for the modulation of the optical properties of GQDs.