Microwave-assisted ultrafast and facile synthesis of fluorescent carbon nanoparticles from a single precursor: preparation, characterization and their application for the highly selective detection of explosive picric acid

An ultrafast and facile method for the preparation of fluorescent nitrogen-doped carbon nanoparticles (CNPs) from a single precursor (ammonium citrate dibasic serving as both the carbon and nitrogen source) has been developed using a cheap home-use microwave oven. The obtained CNPs showed a strong blue fluorescence with a quantum yield of similar to 20% and displayed excitation-independent fluorescence behavior. The effects of preparation conditions on the fluorescence behavior of the CNPs were systematically investigated, while the as-prepared CNPs were thoroughly characterized using various advanced techniques. The mechanism of nanoparticle formation was also discussed and proposed. Furthermore, it was found that, interestingly, explosive picric acid (PA) could quench the fluorescence signal of the CNPs significantly and selectively, while other nitroaromatic explosives have insignificant effect on their fluorescence intensity. The excellent sensing performance for picric acid could be attributed to the synergistic effect of its low molecular orbitals, the presence of fluorescence resonance energy transfer as well as acid-base interactions between the picric acid and fluorescent CNPs. These findings here suggest a simple way to prepare highly fluorescent CNPs, which holds great promise in the development of sensitive and selective sensors for PA detection.