Controllable synthesis of yellow emissive carbon dots by mild heating process and their utility as fluorescent test paper for detection of mercury (II) ions assistants by smartphone

The security of food and drink water is of great concern in our daily life, because the threat from heavy metals pollution in environment is extensively existed. Carbon dots (CDs) is promising for a wide range of applications because of its excellent chemical and optical properties. Herein, yellow emissive carbon dots (YCDs) were constructed by a facile mild condition. The YCDs emitted bright emission at 562 nm with excitation of 420 nm and the quantum yield of 17.44%. The fluorescence of YCDs can be utilized of sensing Hg2+ with limit of 16.8 nM. The mechanism of detection for Hg2+ can be attributed to static quenching effect (SQE) and dynamic quenching effect (DQE) process. A fluorescent portable paper detection platform based on YCDs integrated with a smartphone APP were developed for real-time and rapid analysis of Hg2+ with limit of 0.11 & mu;M. Notably, YCDs were successfully employed to the detection of Hg2+ in various food and real water with recoveries of 97.50 & PLUSMN; 2.63% - 108.64 & PLUSMN; 0.15%, indicated satisfied sensing performance and excellent environmental tolerance. The fluorescence sensing system based on YCDs provided a reference for the construction of portable sensors for hazardous substance monitoring.