Porphyrin-based covalent organic framework integrated with nitrogen doped carbon nanotube as electrode modifier for selective and simultaneous detection of hydroquinone and catechol with high sensitivity

A novel Co-porphyrin-based covalent organic framework (TT-COF(Co)) was synthesized and further integrated with nitrogen doped carbon nanotube (N-CNTs), which was used as electrode modifier material for the application in selective and simultaneous electrochemical detection of hydroquinone (HQ) and catechol (CA). The successful formation of TT-COF(Co)/N-CNTs nanocomposite was confirmed through a series of different characterization techniques, including scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Electrochemical results indicated that TT-COF(Co)/N-CNTs nanocomposite modified electrode had excellent sensing performance for HQ and CA in phosphate buffer, enabling selectively and simultaneously determination of these two dihydroxybenzene isomers. Under optimal testing conditions, linear calibration curves for the selective determination of HQ or CA in the presence of 30 µM of the corresponding isomers were obtained over the concentration range of 0.01–500 µM. The linear ranges for the simultaneous determination of HQ and CA were 0.003–300 µM, with detection limits of 0.81 nM for HQ and 0.74 nM for CA, respectively. The sensor also demonstrated satisfactory selectivity and stability, and was successfully used to analyse HQ and CA in real water samples. Our work made a useful contribution to strategical design of functionalized COFs materials for electrochemical sensing applications.