基于银纳米粒子/氧化石墨烯复合薄膜制备TNP电化学传感器

利用改进的Hummers法制备了氧化石墨烯(GO), 以葡萄糖为还原剂直接在GO表面沉积银纳米粒子(AgNPs)得到性能稳定的AgNPs/GO纳米复合材料;基于该纳米复合材料修饰电极构建了一种新型的2, 4, 6-三硝基苯酚(TNP)电化学传感器。采用原子力显微镜(AFM)、扫描电镜(SEM)、透射电镜(TEM)、紫外可见光谱(UV-Vis)和交流阻抗(EIS)等多种方法对纳米复合薄膜进行了表征;并研究了TNP在复合薄膜修饰电极上的电化学行为和动力学性质。结果表明, AgNPs/GO对TNP有较强的电催化活性, 在复合薄膜修饰电极出现一灵敏的氧化峰和3个还原峰;利用氧化峰可对TNP进行定量分析。同时整个电极过程明显不可逆, 电极反应受到吸附步骤控制;复合膜电极表面覆盖度为5.617×10^-8 mol·cm^-2, 在所研究电位下的速率常数为9.745×10^-5 cm·s^-1。在pH 6.8的磷酸缓冲液中, 当富集电位为-0.70 V, 富集时间为60 s;TNP氧化峰电流与其浓度在5.0×10^-9~1.0×10^-7 mol·L^-1范围内成良好线性关系, 相关系数为0.995 8, 检出限可达1.0×10^-9 mol·L^-1。所制备的电化学传感器稳定性和选择性较好;用于实际水样中TNP的现场快速检测, 加标回收率在 97.6%~103.9%之间。

Preparation of TNP Electrochemical Sensor Based on Silver Nanoparticles/Graphene Oxide Nanocomposite

Graphene oxide (GO) was prepared by a modified Hummers process, and then silver nanoparticles (AgNPs) were directly deposited on the surface of GO using glucose as reducing agent; finally nanocomposite of AgNPs/GO with good stability was obtained. A novel 2,4,6-trinitrophenol (TNP) electrochemical sensor was fabricated based on the prepared nanocomposite modified electrode. The nanocomposite was characterized by atomic force microscope (AFM), scanning electron microscope (SEM), transmission electron microscope (TEM), UV-Vis spectroscopy (UV-Vis) and alternating current impedance (EIS), and the electrochemical behaviors and kinetic properties of TNP on the modified electrode were also investigated. The experimental results showed that a sensitive oxidation peak and three reduction peaks of TNP appeared at the nanocomposite modified electrode. The oxidation peak can be used for quantitative analysis of TNP. Moreover, the whole electrode process was obviously irreversible, and electrode reaction was controlled by the adsorption step. The surface coverage of nanocomposite modified electrode was 5.617×10^-8 mol·cm^-2, and the rate constant was 9.745×10^-5 cm·s^-1 at the fixed potential. In pH 6.8 phosphate buffer, the oxidation peak currents of TNP were linearly dependent on its concentrations in the range of 5.0×10^-9~1.0×10^-7 mol·L^-1 with accumulation time of 60 s at -0.70 V. The correlation coefficient was 0.995 8 and the detection limit was 1.0×10^-9 mol·L^-1. The prepared electrochemical sensor had preferable stability and selectivity, and it could be applied to the quick determination of TNP in real water samples, and the recovery was from 97.6% to 103.9%.