摘要/Abstract

金属有机骨架（MOFs）材料因其结构和组成特点在重金属离子的吸附和预富集方面表现出独特优势，在重金属离子的光学传感方面显示出极大的应用潜力，但其导电性较差，这大大限制了其在电化学传感领域的应用.制备了一种功能化的金属有机骨架复合材料——热还原氧化石墨烯-金-沸石咪唑酯骨架材料（RGO-Au-ZIF-8）.该复合材料具有较本体MOF显著改善的电化学性质，利用其构建电化学传感平台实现了对水相溶液中铅离子（Pb²⁺）和铜离子（Cu²⁺）的同时灵敏检测.借助扫描电子显微镜、透射电子显微镜、紫外可见吸收光谱法和各种电化学技术对所制备材料及其修饰电极的形貌、结构和电化学特性进行了表征.采用阳极溶出伏安法（DPASV）对水相溶液中的Pb²⁺和Cu²⁺进行检测，并对检测溶液pH、沉积时间和沉积电位等实验参数进行了优化.在最优化条件下，该传感平台对Pb²⁺和Cu²⁺的检测线性浓度范围分别为0.005～10（Pb²⁺）和0.01～10（Cu²⁺）μmol·L^-1，检测限为2.6×10^-9（Pb²⁺）和7.8×10^-9（Cu²⁺） mol·L^-1.此外，还对该传感平台的选择性、重现性和稳定性进行了考察，并进行了实际水样中Pb²⁺和Cu²⁺的回收实验.该工作为重金属离子的同时、快速且灵敏的检测提供了一种新的平台，并大大拓展了MOFs材料的电化学应用.
关键词: RGO-Au-ZIF-8, 电化学传感器, 同时检测, 铅离子, 铜离子
Metal organic frameworks (MOFs) have unique advantages in adsorption and preconcentration of heavy metal ions due to their structure and composition characteristics, which make them show great potential in optical sensing of heavy metal ions. However, their applications in the field of electrochemical sensing is greatly limited because of their poor conductivity. In this work, a functionalized MOF composite, thermally reduced graphene oxide-Au nanoparticles-zeolitic imidazolate skeleton material (RGO-Au-ZIF-8), was fabricated. It exhibits much improved electrochemical properties compared with the pristine MOF. A novel electrochemical sensing platform was constructed based on it, and simultaneous detection of lead ions (Pb²⁺) and copper ions (Cu²⁺) in aqueous solution was realized. Specifically, the Au-ZIF-8 was prepared by adding polyvinylpyrrolidone (PVP)-stabilized Au nanoparticles (AuNPs) to the reaction solution of ZIF-8. The modification of AuNPs effectively improved the conductivity of the material. After compounding with RGO, the RGO-Au-ZIF-8 composite was prepared. The RGO was used as scaffold for the Au-ZIF-8 in the composite to increase the effective surface area of electrode and improve conductivity. The morphology and structure of the prepared materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-visible absorption spectroscopy (UV-Vis). The electrochemical properties of the modified electrodes were characterized by various electrochemical techniques. The experimental parameters, such as pH value of working solution, accumulation potential, accumulation time and composition ratio of Au-ZIF-8 to RGO were optimized. Under the optimized conditions, simultaneous and sensitive detection of Pb²⁺ and Cu²⁺ on the prepared electrochemical sensor was realized with the detection limits of 2.6×10^-9 and 7.8×10^-9 mol·L^-1 for Pb²⁺ and Cu²⁺, respectively (S/N=3). The interference test showed that the electrochemical sensor has good selectivity for the detection of Pb²⁺ and Cu²⁺, and further electrochemical studies revealed that the designed sensor has excellent reproducibility and good stability. The result of recovery test indicated that the prepared electrochemical sensor has great potential in Pb²⁺ and Cu²⁺ detection in real water samples. This work provides a new platform for simultaneous, rapid and sensitive detection of heavy metal ions, and greatly expands the electrochemical applications of MOF materials.
Key words: reduced graphene oxide-Au nanoparticles-zeolitic imidazolate skeleton material (RGO-Au-ZIF-8), electrochemical sensor, simultaneous detection, lead ion, copper ion


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