Preparation of pH-responsive fluorescent carbon dots under extreme alkaline conditions

Abstract

Carbon dots (CDs) were prepared via a one-step solvothermal method using L-aspartate as the carbon source and ammonia as the solvent. The prepared CDs exhibited pH-sensitive properties and a color changing response to extreme alkaline pH ranges (12.0–14.0). O-related defect and N-related defect states induced by the protolated amino groups on the CD surfaces alternately dominated the fluorescence emission with a change in pH value, and the luminescence of different defect states was greatly affected by the excitation wavelength, which endowed the CDs with different pH-dependent fluorescence emission behavior under different light excitation. Based on the fluorescent emission behavior, which could be adjusted with a change in pH, the CDs showed potential application value as an instant inspection.