Electrochemiluminescence detection of Cu2+ ions by nitrogen-doped carbon quantum dots and zinc oxide composites

In this study, nitrogen-doped carbon quantum dots and ZnO (N-CQDs/ZnO) composites were prepared to improve the electrochemiluminescence (ECL) performance of carbon quantum dots (CQDs) for detecting copper ions. Nitrogen-doped carbon quantum dots (N-CQDs) were prepared by a pyrolysis method using glucosamine as a carbon source and urea as a nitrogen source. In addition, N-CQDs/ZnO composites were prepared using zinc acetate in the same way, and they were characterized by the ECL method. The ECL performance of composite ZnO materials with paper-based modified electrodes improved, and the principle of signal enhancement of the N-CQDs/ZnO composite material was demonstrated. The paper electrode was modified with the composite material to detect copper ions via the quenching reaction. The results show that the sensitivity and detection limit (6.13 × 10−9 M) of the paper ECL sensor improved across a wide linear detection range (1.0 × 10−8–1.0 × 10−3 M). Therefore, N-CQDs/ZnO composites prepared by this method have potential applications in ECL signal amplification.