Adsorbent-Assisted In Situ Electrocatalysis: Highly Sensitive and Stable Electrochemical Sensor Based on AuNF/COF-SH/CNT Nanocomposites for the Determination of Trace Cu(II)
Fei Pan, Chunyi Tong, Ning Wang, Yeyao Wang, Dawei Pan, Rilong Zhu
Abstract
The weak conductivity of covalent organic frameworks (COFs) limits their wide application in electrochemical sensors. Here, a novel electrochemical sensor (AuNFs/COF-SH/CNTs/GCE) was designed and constructed by a one-step electrochemical deposition of Au nanoflowers (AuNFs) on a hybrid nanocomposite of sulfhydryl-functional covalent organic framework/carbon nanotubes (COF-SH/CNTs) for the determination of Cu(II) in seawater. AuNFs/COF-SH/CNTs/GCE was prepared in a three-step method including in situ synthesis, post-synthesis, and one-step electrochemical deposition. The adsorption and catalytic performances of the modified electrode were improved based on the mechanism of “adsorption-catalysis stripping determination”. By combining the excellent catalytic properties of the AuNFs with the good adsorption capacity of COF-SH toward Cu(II), as well as the good conductivity of CNTs, the AuNFs/COF-SH/CNTs/GCE exhibited excellent performance for the determination of Cu(II). Through optimization of the experimental conditions, a low detection limit of 0.47 nM and a wide linear range of 1.6 nM-4.7 μM were obtained. Moreover, the sensor possessed good stability with a relative standard deviation of less than 5% after 20 repeated measurements. The results are consistent with certified values when used for the determination of certified reference materials. In summary, the AuNFs/COF-SH/CNTs/GCE, with high stability and sensitivity, has been successfully applied for the determination of Cu(II) in seawater samples with satisfactory results.