The Preparation Of N,S Co-doped Dual-emission Carbon:Dots And The Detection Of P-nitrophenol And Copper Ions

Copper is one of the most widely used industrial metal,as well as one of the most discharged pollutants.Recently,investigations on copper-related neurodegenerative diseases has attracted extensive attention.Thus,it is desirable to explore detection method for the monitor of copper content in environmental water.p-Nitrophenol（p-NP）is widely used in insecticidal pesticide,dyes/pigments and pharmaceuticals.However,p-NP can hardly be decomposed in dissimilar surroundings,but it can be accumulated in the food chain easily.If untaken by human body,p-NP can cause methemoglobinemia and damage in liver and kidney。Since p-NP contaminants can cause severe harm to the health of human beings and environment,establishing a rapid,simple,low-cost and sensitive protocol for examining of trace p-NP in environmental samples is of considerable significance.In this study,N,S co-doped dual-emissive carbon dots（N,S-CDs）are prepared by hydrothermal treatment of thiourea and citric acid in N-N dimethylformamide.The as-prepared N,S-CDs exhibit narrow size distribution of 1.20±0.42 nm。X-ray photoelectron spectroscopy（XPS）reveals that the as-prepared CDs consists of carbon（63.35%）,nitrogen（9.69%）,oxygen（24.42%）,and sulfur（2.54%）.The UV-Vis absorption spectra of the CDs is characterized by the peaks centered at 335nm and537nm.The as-prepared CDs exhibit excitation-dependent fluorescent emission with two excitation/emission centers at 380/460 nm and 550/625 nm。The fluorescence excited at 380 nm can be quenched by p-NP due to the overlap of the absorption spectra（300-400 nm）between CDs and p-NP.A detection method for p-NP is accordingly found with a linear range of 0-150μM and a detection limit（LOD）of 6.47μM.High selectivity of the method gives rise to satisfactory results in real water sample test.Meanwhile,the fluorescence of CDs（excited at 550 nm）can be quenched by copper cations and the quenched intensity linearly enhance with the increase of Cu²⁺concentration in the range of 0-10μM.A detection method for Cu²⁺is found with LOD of 0.60μM.Most of the coexisting metal cations and ions exhibit slight interference and thus provides satisfactory results for detection of copper in real water sample.