In-situ laser synthesis of ZIF-67@ZIF-8-derived CoZn@NC/graphene as a flexible electrode for electrochemical metol detection

Abstract

Background Designing a sensitive and selective electrochemical sensor to determine metol (MT), a toxic phenolic substance, has a great significance. The development of new and advanced materials with excellent electrocatalytic properties has been receiving more attention in the field of electrochemical sensor. Metal-organic frameworks (MOFs) derived bimetallic transition metal alloy/carbon composites are regarded as outstanding electron-conductive transport media. However, their preparation always requires a high-temperature and hours of calcination treatment. Consequently, it is vital to advance a user-friendly, straightforward and scalable method to construct MOF derived metal/carbon materials. Results Herein, we developed a two-step laser irradiation process. The first-step laser irradiation made the production of laser-induced graphene (LIG) on a flexible polyimide (PI) film. The second-step laser irradiation transformed a ZIF-67@ZIF-8/LIG into a LIG supported a core-shell structure of CoZn alloy nanoparticle encapsulated in N-doped carbon (CoZn@NC), named as CoZn@NC/LIG. Then, the enhanced electrochemical sensing ability of CoZn@NC/LIG electrode was studied for the detection of MT. The fabricated sensor owned a range of linear quantification of 0.01–10 μM for MT sensing with a low limit of detection (LOD) of 1.48 nM. Moreover, the developed flexible LIG working electrode offered respectable selectivity, acceptable flexibility and high stability. It was then applied to detect MT in actual water samples with exceptional recovery rates, confirming its reliability in complex sample matrices. Significance: Gaining advantages from the combined effects of high electrocatalytic activity of the multilevel CoZn@NC active sites and excellent electroconductibility of 3D hierarchical porous structure of LIG, the established CoZn@NC/LIG flexible electrode achieved highly-sensitive determination of MT. The discoveries of this research present a novel and efficient methodology for designing MOF-derived metal/carbon composites and flexible electrode with excellent performance in environmental analysis.