Antifouling double layers of functionalized-multi-walled carbon nanotubes coated ZnO for sensitive and selective electrochemical detection of catechol

Herein, a novel catechol sensor made of double-layers of functionalized multi-walled carbon nanotubes coated zinc oxide on a glassy carbon electrode (fMWCNTs/ZnO@fMWCNTs/GCE) is synthesized. The FTIR spectrum reveals that the ZnO NPs are successfully functionalized on the fMWCNT while SEM analysis shows granular colloids on the surface of ZnO@fMWCNTs nanocomposites. The XRD study confirms the crystalline nature of the ZnO peaks and the ZnO interaction with fMWCNTs structure. The fabricated sensor responds to a wide linear range of CC concentrations from 10 µM to 200 µM and sensitivity of 0.0022 µA/µM.cm² with a detection and quantification limit of 0.027 µM and 0.092 µM, respectively. Both of the limits are better than previously reported ZnO and fMWCNTs sensors. In addition, the developed fMWCNTs/ZnO@fMWCNTs/GCE demonstrates that the electron transfer is regulated by the adsorption-controlled process and can successfully detect catechol in real water samples with an excellent selectivity against hydroquinone (HQ), phenol (ph), and penta-chlorophenol (p-chph). The developed sensor exhibits satisfactory analytical performance including operational stability of 94.5%, good repeatability with a relative standard deviation (RSD) of 2.15%, and reliable reproducibility of 8 electrodes with an RSD of 3.93%.Research Highlights An antifouling double-layered functionalized multi-walled carbon nanotubes (fMWCNTs) coated zinc oxide nanoparticles (ZnO NPs) is synthesized. The nanocomposite (fMWCNTs/ZnO@fMWCNTs) was fabricated using a one-step in-situ adsorption method. In the new design of the fabricated nanocomposite, the diffusion of electrons is improved by the adsorption control mechanism. The developed sensor is highly sensitive and selective for sensing catechol. It exhibits stable and reproducible responses for practical and real analysis of catechol.