Ravi Pavithra V, Thangadurai Daniel T, Nehru Kasi, Lee Yong Ill, Nataraj Devaraj, Thomas Sabu, Kalarikkal Nandakumar, Jose Jiya
Department of Nanoscience and Technology, Sri Ramakrishana Engineering College, Affiliated to Anna University Coimbatore - 641 022 Tamilnadu India
Department of Chemistry, Anna University - Bharathidasan Institute of Technology Tiruchirappalli - 620 024 Tamilnadu India.
RSC Adv. 2020 Oct 9;10(61):37409-37418. doi: 10.1039/d0ra07555h. eCollection 2020 Oct 7.
Trace determination of radioactive waste, especially Ce, by electrochemical methods has rarely been attempted. Ce is (i) a fluorescence quencher, (ii) an antiferromagnet, and (iii) a superconductor, and it has been incorporated into fast scintillators, LED phosphors, and fluorescent lamps. Although Ce has been utilized in many industries due to its specific properties, it causes severe health problems to human beings because of its toxicity. Nanomaterials with fascinating electrical properties can play a vital role in the fabrication of a sensor device to detect the analyte of interest. In the present study, surfactant-free 1,8-diaminonaphthalene (DAN)-functionalized graphene quantum dots (DAN-GQDs) with nanobud (NB) morphology were utilized for the determination of Ce through electrochemical studies. The working electrode, graphene nanobud (GNB)-modified-carbon felt (CF), was developed by a simple drop-coating method for the sensitive detection of Ce in acetate buffer solution (ABS, pH 4.0 ± 0.05) at a scan rate of 50 mV s using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. CV and DPV studies validated the existence of distinctive peaks at approximately +0.20 and +0.93 V ( SCE), respectively, with a limit of detection of approximately 2.60 μM. Furthermore, electrochemical studies revealed that the GNB-modified-CF electrode was (i) stable even after fifteen cycles, (ii) reproducible, (iii) selective towards Ce, (iv) strongly pH-dependent, and (v) favored Ce sensing only at pH 4.0 ± 0.05. Impedance spectroscopy results indicated that the GNB-modified-CF electrode was more conductive (1.38 × 10 S m) and exhibited more rapid electron transfer than bare CF, which agrees with the attained Randles equivalent circuit. Microscopy (AFM, FE-SEM, and HR-TEM), spectroscopy (XPS and Raman), XRD, and energy-dispersive X-ray (EDX) analyses of the GNB-modified-CF electrode confirmed the adsorption of Ce onto the electrode surface and the size of the electrode material. Ce nanobuds increased from 35-40 to 50-55 nm without changing their morphology. The obtained results provide an insight into the determination of Ce to develop an electrochemical device with low sensitivity.
采用电化学方法对放射性废物尤其是铈进行痕量测定的尝试很少。铈具有以下特性：（i）荧光猝灭剂，（ii）反铁磁体，（iii）超导体，并且已被应用于快速闪烁体、发光二极管荧光粉和荧光灯中。尽管铈因其特殊性质在许多行业得到应用，但其毒性会给人类带来严重的健康问题。具有迷人电学性质的纳米材料在制造用于检测目标分析物的传感装置中可发挥重要作用。在本研究中，利用具有纳米芽（NB）形态的无表面活性剂1,8 - 二氨基萘（DAN）功能化石墨烯量子点（DAN - GQDs）通过电化学研究来测定铈。工作电极，即石墨烯纳米芽（GNB）修饰的碳毡（CF），通过简单的滴涂法制备，用于在乙酸盐缓冲溶液（ABS，pH 4.0 ± 0.05）中以50 mV s的扫描速率使用循环伏安法（CV）和差分脉冲伏安法（DPV）技术灵敏检测铈。CV和DPV研究分别验证了在约 +0.20 V和 +0.93 V（SCE）处存在独特的峰，检测限约为2.60 μM。此外，电化学研究表明GNB修饰的CF电极具有以下特性：（i）即使经过十五个循环仍稳定，（ii）可重现，（iii）对铈具有选择性，（iv）强烈依赖pH值，（v）仅在pH 4.0 ± 0.05时有利于铈传感。阻抗谱结果表明GNB修饰的CF电极导电性更强（1.38 × 10 S m），并且与裸CF相比表现出更快的电子转移，这与所获得的兰德尔等效电路一致。对GNB修饰的CF电极进行显微镜（AFM、FE - SEM和HR - TEM）、光谱（XPS和拉曼）、XRD和能量色散X射线（EDX）分析，证实了铈在电极表面的吸附以及电极材料的尺寸。铈纳米芽从35 - 40 nm增加到50 - 55 nm，但其形态未改变。所获得的结果为开发低灵敏度的电化学装置来测定铈提供了见解。
