One-pot fabrication of fluorescent carbon nitride nanoparticles with high crystallinity as a highly selective and sensitive sensor for free chlorine

A facile one-pot solvothermal strategy was used to prepare fluorescent carbon nitride nanoparticles (CNNPs) using tartaric acid and urea as carbon and nitrogen sources at relatively low temperatures. The obtained CNNPs were characterized by multiple analytical techniques. The CNNPs with fluorescence (FL) quantum yield up to 17.9% exhibited excellent selectivity and sensitivity of fluorescence quenching for free chlorine. The quenching rate was quick, and the linear response range of free chlorine was from 0 to 30   μM. The limit of detection (LOD) was as low as 13   nM, which was much lower than that of the most widely used N,N -diethyl- p -phenylenediamine (DPD) colorimetric method. This sensing system exhibits many advantages, such as short response time (less than 1   min), excellent selectivity, high sensitivity, and wide linear response range. The results show that this method has promising potential applications in the detection of free chlorine in real water samples.