Determination of ferric ion via its effect on the enhancement of the chemiluminescece of the permanganate-sulfite system by nitrogen-doped graphene quantum dots.

Nitrogen-doped graphene quantum dots (NGQDs) are shown to strongly enhance the integrated chemiluminescence (CL) of the permanganate-sulfite system. The mechanism of enhancement was investigated, and the catalytic effect of the NGQDs was proven. In contrast to other carbon-based nanomaterials, the enhancement by NGQDs is independent of particle size and surface. However, the pyridinic nitrogen on the surface of the NGQDs facilitates the transformation of dissolved oxygen into H2O2 and the generation of hydroxyl radicals. This induces the increase of CL intensity. However, in the presence of Fe3+, the nitrogen functions and phenol groups on the surface of the NGQDs will chelate it, and the CL signal is decreased as a result. This effect was used to design an assay for Fe3+ that has a wide response range (1 × 10-8 - 1 × 10-6 M) and a 4 nM detection limit. The method was successfully applied to the determination of Fe3+ in spiked real water samples. Graphical abstract Nitrogen-doped graphene quantum dots (NGQDs) are demonstrated to strongly enhance the integrated chemiluminescence (CL) of the permanganate-sulfite system. The pyridinic N-atoms in NGQDs facilitate the transformation from dissolved oxygen into H2O2 and the generation of •OH radicals. This leads to the highly enhanced CL of the system. In the presence of Fe3+, which will be chelated by the nitrogen functions and phenol groups on the surface of the NGQDs, the CL signal is decreased.

A novel electrochemiluminescence resonance energy transfer system of luminol-graphene quantum dot composite and its application in H2O2 detection.

Luminol-nitrogen doped graphene quantum dot (luminol-NGQDs) nanocomposite was synthesized and a novel electrochemiluminescence resonance energy transfer (ECL-RET) process occurred between luminol as the donor and NGQDs as the acceptor in the composite. This ECL-RET effect helped luminol-NGQDs composite produced an anodic ECL signal without coreactants. The ECL-RET mechanism was also studied based on the fluorescence spectra, the ultraviolet-visible absorption spectra and the electrochemiluminescence (ECL) spectra. Based on the significant sensitization effect of hydrogen peroxide on luminol-NGQDs ECL signal, an ECL method for the sensitive determination of hydrogen peroxide was established and then applied to the detection of hydrogen peroxide in water samples.