Hydrogen peroxide enhanced glow-type chemiluminescence of hydrazine hydrate modified carbon quantum dots-potassium...

Most known chemiluminescence (CL) systems are flash-type that generate weak luminescence and decline quickly after dozens of seconds, while the glow-type CL systems have stable emission for an extended period to achieve accurate quantitation. In this work, a long-term CL system based on hydrazine-hydrate (N₂H₄·H₂O) modified carbon quantum dots (N-CQDs) as a luminescent probe, with K₂S₂O₈ and H₂O₂ as co-reactants, was proposed. The CL emission enhanced by H₂O₂ increased 18-fold more than that of N-CQDs and K₂S₂O₈ direct reaction, and decayed by 5% of the maximum intensity over 700 s. In the reaction system, K₂S₂O₈ and H₂O₂ co-reactants can promote each other to continuously generate corresponding radicals (•OH, O₂^•-, ¹O₂), which in turn trigger the CL emission of N-CQDs. This phenomenon was identified as the primary cause for the production of persistent CL. In addition, a stable and selective CL sensor based on the N-CQDs-K₂S₂O₈-H₂O₂ CL enhancing system was developed for ascorbic acid quantitation in the linear range from 0.1 to 10.0 mM with a detection limit of 0.036 mM. The method has been applied to the analysis of tablet samples and holds potential in pharmaceutical analysis field.