High Quantum Yield Fluorescent Chitosan-Based Carbon Dots for the Turn-On-Off-On Detection of Cr(VI) and H₂O₂

One-pot hydrothermal carbonization approach was employed to synthesize the blue-emission carbon dots derived from chitosan (Cs) and o-phenylenediamine (OPD). The Cs-based carbon dots (Cs-CDs) possessed a certain high quantum yield of 58% and exhibited excellent solubility, stability and fluorescence response in aqueous solutions. The Cs-CDs were designed as a sensor for Cr(VI) and H2O2 determination. The sensing strategy of Cr(VI) was based on the inner filter effect (IFE) and static quenching effect (SQE), showing a good linear correlation ranging from 1 to 130μM with a detection limit (LOD) of 0.91μM. In addition, the determination for H2O2 was attributed to the elimination of IFE (EIFE) due to the reduction reaction and the detection for H2O2 was in the linear range from 1.0 to 200.0μM with LOD of 0.51μM. Finally, the proposed designed sensor could be simply applied for detection of Cr(VI) and H2O2 in real samples.