No abstract

In this work, we report the synthesis of nitrogen (N)-doped carbon nanodots (N-CNDs) with an N doping level of 3.6 at. % by hydrothermal treatment of prawn shell and their application as fluorophores for selective and sensitive fluorescence detection of NO2 – in water. The results demonstrate that NO2 – detection by directly fluorescent quenching at N-CNDs fluorophores can achieve an analytical detection linear range up to 1.0 mM with a detection limit of 1.0 μM. The obtained detection limit of NO2 – using N-CNDs fluorophores is dramatically lower than the maximum limit value of 3.0 mg L–1 (namely, 65 μM) for NO2 – in drinking water ruled by the World Health Organization (WHO), which is very important for a practical application of the developed analytical method. The interference experiments indicate that only I– ions among all common anions and cations investigated show very adverse influence on selective detection of NO2 – by this developed N-CNDs based fluorescent determination method. Further, the fluorescence quenching of N-CNDs on NO2 – concentrations under the given experimental conditions fits a linear Stern–Volmer relationship very well, indicating a dynamic quenching process in this N-CNDs/NO2 – fluorescence sensing system. A fluorescent quenching mechanism resulted from the redox reaction between the excited oxidation state of N-CNDs under light excitation and NO2 – was proposed based on the experimental results. The findings in this work exhibit the great potential using cheap and abundant biomass-derived N-doped carbon nanodots as fluorophores for selective and sensitive determination of environmentally harmful anions.