ZIF-derived necklace-like N-doped porous carbon@MWCNTs loaded with Cu NPs for enhanced electrochemical sensing of dihydroxybenzene isomers

Hydroquinone (HQ), catechol (CC), and resorcinol (RS), as toxic and hardly degradable dihydroxybenzene isomers, pose threats to the environment and human health. In this study, using multi - walled carbon nanotubes (MWCNTs) and ZIF-8 as precursors, a necklace-like N-doped carbon polyhedron/carbon nanotube composite loaded with Cu nanoparticle (Cu NPs/NC@MWCNTs) electrocatalyst was prepared by hydrothermal and high-temperature carbonization processes. Comprehensive characterization data from XRD, SEM, TEM, XPS, BET, and Raman spectroscopy confirmed that the unique necklace-like porous structure and synergistic effect between ZIF-derived N-doped carbon polyhedra and MWCNTs regulate the electronic structure and surface properties of the catalyst, thereby accelerating the electron transfer rate. Under neutral conditions, the Cu NPs/NC@MWCNTs/CP electrode exhibits good electrocatalytic activity for the separate or simultaneous determination of three dihydroxybenzene isomers (HQ, CC, and RS) with low detection limit of 0.16 μM, 0.14 μM and 0.10 μM (S/N = 3), respectively. Density functional theory (DFT) calculations further reveal the differences in selectivity and sensitivity among the three isomers. In addition, this sensor has been successfully applied to the detection of three dihydroxybenzene isomers in actual environmental water samples, achieving satisfactory recovery rates of 97.8–106 %.