Ag and N-doped carbon dot-enhanced H2O2-Co2+ chemiluminescence and its application for the determination of Co2+ and hydroquinone

In this study, Ag and N-doped carbon dots (Ag-NCDs) were used to enhance the ultraweak H2O2-Co2+ (a Fenton-like reaction) chemiluminescence (CL) reaction, in which Ag-NCDs were found to have the functions of catalyst, chelator, and luminophore. Under the co-catalysis of Co2+ and Ag-NCDs, H2O2 dissociation was facilitated, resulting in increased generation of active (OH)-O-center dot and O-center dot(2)- radicals. Thus, the CL intensity of the Ag-NCDs-H2O2-Co2+ system was significantly higher than that of the H2O2-Co2+ system and the Ag-NCDs-H2O2 system. Co2+ catalyzes the reaction through complex formation with Ag-NCDs' surface amino groups, thereby accelerating H2O2 decomposition. The CL intensity of the H2O2-Co2+ system increased with increasing Co2+ concentration in the range from 0.4 mM to 40.0 mM with a detection limit of 0.07 mM. Furthermore, we observed that HQ can effectively quench the Ag-NCDs-H2O2-Co2+ CL signal. This led to the application of the CL system for HQ detection, achieving quantitative measurements within the 0.2-20.0 mM concentration range with a detection limit of 0.04 mM. It also enabled sequential determination of Co2+ and HQ in egg yolk, vitamin B12, and water samples, offering simplicity, time-saving, and higher selectivity.

Automated summary

In this study, Ag and N-doped carbon dots (Ag-NCDs) were used to enhance the ultraweak H2O2-Co2+ chemiluminescence reaction. Ag-NCDs acted as catalyst, chelator, and luminophore, facilitating H2O2 dissociation and generating more active radicals. The study also developed a chemiluminescence system for HQ detection and enabled sequential determination of Co2+ and HQ in different samples, providing simplicity, efficiency, and selectivity.