The Construction Of Electrochemical Sensor Based On Carbon Dots And Its Analytical Application For 2,4-Dichlorophenol

As an important intermediate, 2,4-dichlorophenol(2,4-DCP) is extensively used for herbicides, fungicides and insecticides in the agriculture. However, it poses a serious ecological problem as an environmental pollutant and seriously affects both public health and environmental quality, which is due to its highly toxic, poorly biodegradable and potentially carcinogenic, and that requires to develop a simple, fast and sensitive analytical method for it. As a newly emerged fluorescent nanoparticle, carbon dots(CDs) have shown enormous potential for a wide range of applications, including bioimaging, biosensing, chemical sensing, photocatalysis and electrocatalysis. Properties of CDs, such as low toxicity, environmental friendliness, chemical stability and good conductivity make it possible to develop highly sensitive sensing platforms based on it. In the present work, we fabricated 2,4-DCP electrochemical sensors based on carbon dots, graphene and silver nanoparticles through synergic catalysis effects and investigated the electrocatalytic property of the modified electrodes to 2,4-DCP. Performance of the sensors and electric catalytic mechanism were discussed, and the sensors were successfully applied for the analysis of real samples. 1. Determination of 2,4-dichlorophenol in lake based on CDs-CTAB composite film modified glassy carbon electrodeIn this work, a novel and sensitive electrochemical sensor for 2, 4-dichlorophenol(2, 4-DCP) based on a nanocomposite of carbon dots(CDs), hexadecyltrimethyl ammonium bromide(CTAB) and chitosan(CS) was constructed through electrostatic self-assembly technology. The nanocomposite of CDs-CTAB-CS introduced a favorable access for the electron transfer and exhibited excellent electrocatalytic activity towards the oxidation of 2,4-DCP. The prepared nanocomposite was characterized by transmission electron microscopy(TEM), ultraviolet and visible spectrometry(UV-vis), Fourier transform infrared spectrometry(FT-IR) and electrochemical impedance spectra(EIS). Differential pulse voltammetry(DPV) was used for the quantitative determination of 2,4-DCP. Under the optimized experimental conditions, the oxidation peak currents of 2,4-DCP were proportional to its concentrations in the range from 0.04 to 8.0 μmolL-1 with a detection limit as 0.01 μmolL-1. The newly developed method was successfully applied for the determination of 2,4-DCP in waste water with satisfactory recoveries. 2. Determination of 2,4-dichlorophenol in lake based on Gr-CTAB-CDs composite film modified glassy carbon electrodeIn this work, a sensitive and selective electrochemical sensor based on graphene(Gr), carbon dots(CDs) and hexadecyltrimethyl ammonium bromide(CTAB) was fabricated for the determination of 2, 4-dichlorophenol(2, 4-DCP), which introduced a favorable access for the electron transfer and exhibited excellent electrocatalytic activity towards the oxidation of 2,4-DCP. This increase in electrochemical response is ascribed to the unique structure of the Gr-CTAB-CDs composite, which was fabricated through interaction of carboxyl groups from carbon dots and the long hydrophobic chain in CTAB. The prepared nanocomposite was characterized by transmission electron microscopy(TEM), ultraviolet and visible spectrometry(UV-vis), Fourier transform infrared spectrometry(FT-IR) and electrochemical impedance spectra(EIS). Linear sweep voltammetry(LSV) was used for the quantitative determination of 2,4-DCP. Under optimized conditions, the oxidation peak currents of 2,4-DCP were proportional to its concentrations in the range of 0.01-15.0 μmol L-1 with a detection limit as 0.003 μmol L-1. This electrochemical sensor showed good sensitivity, selectivity, wide linear range, and has been successfully applied in the determination of 2,4-DCP in real water samples. 3. Determination of 2,4-dichlorophenol in lake based on Ag NPs/CDs-CTAB composite film modified glassy carbon electrodeIn this work, a novel and highly sensitive electrochemical sensor for 2, 4-dichlorophenol(2, 4-DCP) was developed based on a nanocomposite of carbon dots- dispersed Ag nanoparticles(Ag NPs-CDs) and hexadecyltrimethyl ammonium bromide(CTAB), which remarkably increased the electrochemical response of 2, 4-DCP compared to that on glassy carbon electrode. The nanocomposite of Ag NPs/CDs-CTAB was fabricated by a facile and green approach, introducing a favorable access for the electron transfer and exhibiting excellent electrocatalytic activity towards the oxidation of 2,4-DCP. The prepared nanocomposite was characterized by various techniques. Linear sweep voltammetry(LSV) was used for the quantitative determination of 2,4-DCP. Under the optimized experimental conditions, the oxidation peak currents of 2,4-DCP were proportional to its concentrations in the range of 0.004-8.0 μmolL-1 and 8.0- 40.0 μmol L-1 with a detection limit as 0.001 μmolL-1. The method has been successfully applied for the determination of 2,4-DCP in waste water with satisfactory recoveries and the proposed Ag NPs/CDs-CTAB electrode system provides an operational access to design simpler, more sensitive and more environment-friendly sensors based on Ag NPs/CDs nanocomposite.