The fabrication of N-doped carbon dots by methionine and their utility in sensing Cu2+ in real water

Copper ions (Cu2+) are ubiquitous in the ecosystem and cause serious environmental pollution, posing a threat to human health. Therefore, sensitive detection of Cu2+ is urgently needed. Herein, we employed a solvothermal method to prepare blue-emitting carbon dots (Met-CDs) using formamide (FA) and methionine (Met) as precursors, with a high quantum yield (QY) of 38%. Based on the good optical stability of Met-CDs and selective quenching by Cu2+, a sensitive probe using Met-CDs for the detection of Cu2+ in water was successfully designed. Within the linear range of 0.15–2 μM, the limit of detection (LOD) was determined to be as low as 47.7 nM, enabling the quantitative detection of Cu2+. Moreover, the recovery data of the spiked analysis of lake/river water samples were also satisfactory and verified the feasibility of the probe by the analysis of Cu2+ in natural conditions.